/*
** parse.y - mruby parser
**
** See Copyright Notice in mruby.h
*/

%{
#undef PARSER_DEBUG
#ifdef PARSER_DEBUG
# define YYDEBUG 1
#endif
#define YYSTACK_USE_ALLOCA 1

#include <ctype.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <mruby.h>
#include <mruby/compile.h>
#include <mruby/proc.h>
#include <mruby/error.h>
#include <mruby/throw.h>
#include <mruby/string.h>
#include <mruby/dump.h>
#include <mruby/internal.h>
#include "node.h"

#define YYLEX_PARAM p

#define mrbc_malloc(s) mrb_basic_alloc_func(NULL,(s))
#define mrbc_realloc(p,s) mrb_basic_alloc_func((p),(s))
#define mrbc_free(p) mrb_basic_alloc_func((p),0)

typedef mrb_ast_node node;
typedef struct mrb_parser_state parser_state;
typedef struct mrb_parser_heredoc_info parser_heredoc_info;

static int yyparse(parser_state *p);
static int yylex(void *lval, void *lp, parser_state *p);
static void yyerror(void *lp, parser_state *p, const char *s);
static void yywarning(parser_state *p, const char *s);
static void backref_error(parser_state *p, node *n);
static void void_expr_error(parser_state *p, node *n);
static void tokadd(parser_state *p, int32_t c);
static const char* tok(parser_state *p);
static int toklen(parser_state *p);

/* Forward declarations for variable-sized simple node functions */

/* Forward declarations for variable-sized advanced node functions */

/* Helper function to check node type for both traditional and variable-sized nodes */
static mrb_bool node_type_p(node *n, enum node_type type);

#define identchar(c) (ISALNUM(c) || (c) == '_' || !ISASCII(c))

typedef unsigned int stack_type;

#define BITSTACK_PUSH(stack, n) ((stack) = ((stack)<<1)|((n)&1))
#define BITSTACK_POP(stack)     ((stack) = (stack) >> 1)
#define BITSTACK_LEXPOP(stack)  ((stack) = ((stack) >> 1) | ((stack) & 1))
#define BITSTACK_SET_P(stack)   ((stack)&1)

#define COND_PUSH(n)    BITSTACK_PUSH(p->cond_stack, (n))
#define COND_POP()      BITSTACK_POP(p->cond_stack)
#define COND_LEXPOP()   BITSTACK_LEXPOP(p->cond_stack)
#define COND_P()        BITSTACK_SET_P(p->cond_stack)

#define CMDARG_PUSH(n)  BITSTACK_PUSH(p->cmdarg_stack, (n))
#define CMDARG_POP()    BITSTACK_POP(p->cmdarg_stack)
#define CMDARG_LEXPOP() BITSTACK_LEXPOP(p->cmdarg_stack)
#define CMDARG_P()      BITSTACK_SET_P(p->cmdarg_stack)

#define SET_LINENO(c,n) (((struct mrb_ast_var_header*)(c))->lineno = (n))

#define NUM_SUFFIX_R   (1<<0)
#define NUM_SUFFIX_I   (1<<1)

static inline mrb_sym
intern_cstr_gen(parser_state *p, const char *s)
{
  return mrb_intern_cstr(p->mrb, s);
}
#define intern_cstr(s) intern_cstr_gen(p,(s))

static inline mrb_sym
intern_gen(parser_state *p, const char *s, size_t len)
{
  return mrb_intern(p->mrb, s, len);
}
#define intern(s,len) intern_gen(p,(s),(len))

#define intern_op(op) MRB_OPSYM(op)

static mrb_sym
intern_numparam_gen(parser_state *p, int num)
{
  char buf[3];
  buf[0] = '_'; buf[1] = '0'+num; buf[2] = '\0';
  return intern(buf, 2);
}
#define intern_numparam(n) intern_numparam_gen(p,(n))

static void
cons_free_gen(parser_state *p, node *cons)
{
  cons->cdr = p->cells;
  p->cells = cons;
}
#define cons_free(c) cons_free_gen(p, (c))

static void*
parser_palloc(parser_state *p, size_t size)
{
  void *m = mempool_alloc(p->pool, size);

  if (!m) {
    MRB_THROW(p->mrb->jmp);
  }
  return m;
}

#define parser_pfree(ptr) do { if (sizeof(node) <= sizeof(*(ptr))) cons_free((node*)ptr);} while (0)

static node*
cons_gen(parser_state *p, node *car, node *cdr)
{
  struct mrb_ast_node *c;

  /* Try to reuse from free list first - only for 16-byte nodes */
  if (p->cells) {
    c = (struct mrb_ast_node*)p->cells;
    p->cells = p->cells->cdr;
  }
  else {
    c = (struct mrb_ast_node*)parser_palloc(p, sizeof(struct mrb_ast_node));
  }
  c->car = car;
  c->cdr = cdr;
  /* Don't initialize location fields for structure nodes - saves CPU */
  return (node*)c;
}

/* Head-only location optimization: separate functions for head vs structure nodes */
#define cons(a,b) cons_gen(p,(a),(b))           /* Structure nodes - no location */
/* Initialize variable node header */
static void
init_var_header(struct mrb_ast_var_header *header, parser_state *p, enum node_type type)
{
  header->lineno = p->lineno;
  header->filename_index = p->current_filename_index;
  header->node_type = (uint8_t)type;

  /* Handle file boundary edge case: this node is reduced from a token that
     was buffered by bison lookahead before partial_hook switched the file,
     so attribute it to the previous file at its last known lineno rather
     than the new file at lineno=0. */
  if (p->lineno == 0 && p->current_filename_index > 0) {
    header->filename_index--;
    header->lineno = p->prev_file_lineno;
  }
}

/* Combined allocate + init header helper */
static inline void*
new_node(parser_state *p, size_t size, enum node_type type)
{
  void *n = parser_palloc(p, size);
  init_var_header((struct mrb_ast_var_header*)n, p, type);
  return n;
}

/* Type-safe macro wrapper for node allocation */
#define NEW_NODE(type_name, node_type) \
  (struct mrb_ast_##type_name##_node*)new_node(p, sizeof(struct mrb_ast_##type_name##_node), node_type)

static node*
list1_gen(parser_state *p, node *a)
{
  return cons(a, 0);
}
#define list1(a) list1_gen(p, (a))

static node*
list2_gen(parser_state *p, node *a, node *b)
{
  return cons(a, cons(b, 0));
}
#define list2(a,b) list2_gen(p, (a),(b))

static node*
list3_gen(parser_state *p, node *a, node *b, node *c)
{
  return cons(a, cons(b, cons(c, 0)));
}
#define list3(a,b,c) list3_gen(p, (a),(b),(c))

static node*
append_gen(parser_state *p, node *a, node *b)
{
  node *c = a;

  if (!a) return b;
  if (!b) return a;
  while (c->cdr) {
    c = c->cdr;
  }
  c->cdr = b;
  return a;
}
#define append(a,b) append_gen(p,(a),(b))
#define push(a,b) append_gen(p,(a),list1(b))

static char*
parser_strndup(parser_state *p, const char *s, size_t len)
{
  char *b = (char*)parser_palloc(p, len+1);

  memcpy(b, s, len);
  b[len] = '\0';
  return b;
}
#undef strndup
#define strndup(s,len) parser_strndup(p, s, len)

static char*
parser_strdup(parser_state *p, const char *s)
{
  return parser_strndup(p, s, strlen(s));
}
#undef strdup
#define strdup(s) parser_strdup(p, s)

static void
dump_int(uint16_t i, char *s)
{
  char *p = s;
  char *t = s;

  while (i > 0) {
    *p++ = (i % 10)+'0';
    i /= 10;
  }
  if (p == s) *p++ = '0';
  *p = 0;
  p--;  /* point the last char */
  while (t < p) {
    char c = *t;
    *t++ = *p;
    *p-- = c;
  }
}

/* xxx ----------------------------- */

static node*
local_switch(parser_state *p)
{
  node *prev = p->locals;

  p->locals = cons(0, 0);
  return prev;
}

static void
local_resume(parser_state *p, node *prev)
{
  p->locals = prev;
}

static void
local_nest(parser_state *p)
{
  p->locals = cons(0, p->locals);
}

static void
local_unnest(parser_state *p)
{
  if (p->locals) {
    p->locals = p->locals->cdr;
  }
}

static mrb_bool
local_var_p(parser_state *p, mrb_sym sym)
{
  const struct RProc *u;
  node *l = p->locals;

  while (l) {
    node *n = l->car;
    while (n) {
      if (node_to_sym(n->car) == sym) return TRUE;
      n = n->cdr;
    }
    l = l->cdr;
  }

  u = p->upper;
  while (u && !MRB_PROC_CFUNC_P(u)) {
    const struct mrb_irep *ir = u->body.irep;
    const mrb_sym *v = ir->lv;
    int i;

    if (v) {
      for (i=0; i+1 < ir->nlocals; i++) {
        if (v[i] == sym) return TRUE;
      }
    }
    if (MRB_PROC_SCOPE_P(u)) break;
    u = u->upper;
  }
  return FALSE;
}

static void
local_add_f(parser_state *p, mrb_sym sym)
{
  if (p->locals) {
    node *n = p->locals->car;
    while (n) {
      if (node_to_sym(n->car) == sym) {
        mrb_int len;
        const char* name = mrb_sym_name_len(p->mrb, sym, &len);
        if (len > 0 && name[0] != '_') {
          yyerror(NULL, p, "duplicated argument name");
          return;
        }
      }
      n = n->cdr;
    }
    p->locals->car = push(p->locals->car, sym_to_node(sym));
  }
}

static void
local_add(parser_state *p, mrb_sym sym)
{
  if (!local_var_p(p, sym)) {
    local_add_f(p, sym);
  }
}

/* allocate register for block */
#define local_add_blk(p) local_add_f(p, 0)

static void
local_add_kw(parser_state *p, mrb_sym kwd)
{
  /* allocate register for keywords hash */
  local_add_f(p, kwd ? kwd : intern_op(pow));
}

static node*
locals_node(parser_state *p)
{
  return p->locals ? p->locals->car : NULL;
}

/* Helper function to check node type for both traditional and variable-sized nodes */
static mrb_bool
node_type_p(node *n, enum node_type type)
{
  if (!n) return FALSE;

  /* Check if this is a variable-sized node */
  struct mrb_ast_var_header *header = (struct mrb_ast_var_header*)n;
  return ((enum node_type)header->node_type == type);
}

/* Helper functions for variable-sized node detection */
static enum node_type
node_type(node *n)
{
  if (!n) return (enum node_type)0;

  /* Try to interpret as variable-sized node */
  struct mrb_ast_var_header *header = (struct mrb_ast_var_header*)n;
  enum node_type type = (enum node_type)header->node_type;

  /* Validate that the node type is within valid range for variable-sized nodes */
  if (type >= NODE_SCOPE && type < NODE_LAST) {
    return type;
  }

  /* If node type is invalid, this is likely a cons-list node */
  /* Return a special sentinel value to indicate cons-list fallback */
  return NODE_LAST; /* Use NODE_LAST as sentinel for cons-list nodes */
}

static void
nvars_nest(parser_state *p)
{
  p->nvars = cons(int_to_node(0), p->nvars);
}

static void
nvars_block(parser_state *p)
{
  p->nvars = cons(int_to_node(-2), p->nvars);
}

static void
nvars_unnest(parser_state *p)
{
  p->nvars = p->nvars->cdr;
}

/* struct: scope_node(locals, body) */
static node*
new_scope(parser_state *p, node *body)
{
  struct mrb_ast_scope_node *scope_node = NEW_NODE(scope, NODE_SCOPE);
  scope_node->locals = locals_node(p);
  scope_node->body = body;
  return (node*)scope_node;
}

/* struct: stmts_node(stmts) - uses cons list */
static node*
new_stmts(parser_state *p, node *body)
{
  struct mrb_ast_stmts_node *n = NEW_NODE(stmts, NODE_STMTS);
  n->stmts = body ? list1(body) : 0;  /* Wrap single statement in cons-list */

  return (node*)n;
}

/* Helper: push statement to stmts node */
static node*
stmts_push(parser_state *p, node *stmts, node *stmt)
{
  struct mrb_ast_stmts_node *n = stmts_node(stmts);
  n->stmts = push(n->stmts, stmt);
  return stmts;
}

/* struct: begin_node(body) */
static node*
new_begin(parser_state *p, node *body)
{
  struct mrb_ast_begin_node *begin_node = NEW_NODE(begin, NODE_BEGIN);
  begin_node->body = body;
  return (node*)begin_node;
}

#define newline_node(n) (n)

/* struct: rescue_node(body, rescue_clauses, else_clause) */
static node*
new_rescue(parser_state *p, node *body, node *resq, node *els)
{
  struct mrb_ast_rescue_node *n = NEW_NODE(rescue, NODE_RESCUE);
  n->body = body;
  n->rescue_clauses = resq;
  n->else_clause = els;

  return (node*)n;
}

static node*
new_mod_rescue(parser_state *p, node *body, node *resq)
{
  return new_rescue(p, body, list1(list3(0, 0, resq)), 0);
}

/* struct: ensure_node(body, ensure_clause) */
static node*
new_ensure(parser_state *p, node *a, node *b)
{
  struct mrb_ast_ensure_node *ensure_node = NEW_NODE(ensure, NODE_ENSURE);
  ensure_node->body = a;
  ensure_node->ensure_clause = b;
  return (node*)ensure_node;
}

/* struct: nil_node() */
static node*
new_nil(parser_state *p)
{
  struct mrb_ast_nil_node *n = NEW_NODE(nil, NODE_NIL);

  return (node*)n;
}

/* struct: true_node() */
static node*
new_true(parser_state *p)
{
  struct mrb_ast_true_node *n = NEW_NODE(true, NODE_TRUE);

  return (node*)n;
}

/* struct: false_node() */
static node*
new_false(parser_state *p)
{
  struct mrb_ast_false_node *n = NEW_NODE(false, NODE_FALSE);

  return (node*)n;
}

/* struct: alias_node(new_name, old_name) */
static node*
new_alias(parser_state *p, mrb_sym a, mrb_sym b)
{
  struct mrb_ast_alias_node *alias_node = NEW_NODE(alias, NODE_ALIAS);
  alias_node->new_name = a;
  alias_node->old_name = b;
  return (node*)alias_node;
}

/* struct: if_node(cond, then_body, else_body) */
static node*
new_if(parser_state *p, node *condition, node *then_body, node *else_body)
{
  void_expr_error(p, condition);

  struct mrb_ast_if_node *n = NEW_NODE(if, NODE_IF);
  n->condition = condition;
  n->then_body = then_body;
  n->else_body = else_body;

  return (node*)n;
}

/* struct: while_node(cond, body) */
static node*
new_while(parser_state *p, node *condition, node *body)
{
  void_expr_error(p, condition);

  struct mrb_ast_while_node *n = NEW_NODE(while, NODE_WHILE);
  n->condition = condition;
  n->body = body;

  return (node*)n;
}

/* struct: until_node(cond, body) */
static node*
new_until(parser_state *p, node *condition, node *body)
{
  void_expr_error(p, condition);

  struct mrb_ast_until_node *n = NEW_NODE(until, NODE_UNTIL);
  n->condition = condition;
  n->body = body;

  return (node*)n;
}

/* struct: while_node(cond, body) */
static node*
new_while_mod(parser_state *p, node *condition, node *body)
{
  node *while_node = new_while(p, condition, body);
  struct mrb_ast_while_node *n = (struct mrb_ast_while_node*)while_node;
  n->header.node_type = NODE_WHILE_MOD;
  return while_node;
}

/* struct: until_node(cond, body) */
static node*
new_until_mod(parser_state *p, node *a, node *b)
{
  node *until_node = new_until(p, a, b);
  struct mrb_ast_until_node *n = (struct mrb_ast_until_node*)until_node;
  n->header.node_type = NODE_UNTIL_MOD;
  return until_node;
}


/* struct: for_node(var, obj, body) */
static node*
new_for(parser_state *p, node *v, node *o, node *b)
{
  void_expr_error(p, o);

  struct mrb_ast_for_node *n = NEW_NODE(for, NODE_FOR);
  n->var = v;
  n->iterable = o;
  n->body = b;

  return (node*)n;
}

/* struct: case_node(expr, when_clauses) - uses cons list */
static node*
new_case(parser_state *p, node *a, node *b)
{
  void_expr_error(p, a);

  struct mrb_ast_case_node *n = NEW_NODE(case, NODE_CASE);
  n->value = a;
  n->body = b;

  return (node*)n;
}

/* Pattern matching case/in expression */
static node*
new_case_match(parser_state *p, node *val, node *in_clauses)
{
  void_expr_error(p, val);

  struct mrb_ast_case_match_node *n = NEW_NODE(case_match, NODE_CASE_MATCH);
  n->value = val;
  n->in_clauses = in_clauses;

  return (node*)n;
}

/* Create value pattern node */
static node*
new_pat_value(parser_state *p, node *val)
{
  struct mrb_ast_pat_value_node *n = NEW_NODE(pat_value, NODE_PAT_VALUE);
  n->value = val;
  return (node*)n;
}

/* Create variable pattern node */
static node*
new_pat_var(parser_state *p, mrb_sym name)
{
  struct mrb_ast_pat_var_node *n = NEW_NODE(pat_var, NODE_PAT_VAR);
  n->name = name;
  /* Register as local variable if not wildcard */
  if (name) {
    local_add(p, name);
  }
  return (node*)n;
}

/* Create pin pattern node (^var) */
static node*
new_pat_pin(parser_state *p, mrb_sym name)
{
  struct mrb_ast_pat_pin_node *n = NEW_NODE(pat_pin, NODE_PAT_PIN);
  n->name = name;
  /* Pin operator references existing variable, does not create new binding */
  return (node*)n;
}

/* Create as pattern node (pattern => var) */
static node*
new_pat_as(parser_state *p, node *pattern, mrb_sym name)
{
  struct mrb_ast_pat_as_node *n = NEW_NODE(pat_as, NODE_PAT_AS);
  n->pattern = pattern;
  n->name = name;
  local_add(p, name);
  return (node*)n;
}

/* Create alternative pattern node (pat1 | pat2) */
static node*
new_pat_alt(parser_state *p, node *left, node *right)
{
  struct mrb_ast_pat_alt_node *n = NEW_NODE(pat_alt, NODE_PAT_ALT);
  n->left = left;
  n->right = right;
  return (node*)n;
}

/* Create array pattern node [a, b, *rest, c] */
static node*
new_pat_array(parser_state *p, node *pre, node *rest, node *post)
{
  struct mrb_ast_pat_array_node *n = NEW_NODE(pat_array, NODE_PAT_ARRAY);
  n->pre = pre;
  n->rest = rest;
  n->post = post;
  return (node*)n;
}

/* Create find pattern node [*pre, elems, *post] */
static node*
new_pat_find(parser_state *p, node *pre, node *elems, node *post)
{
  struct mrb_ast_pat_find_node *n = NEW_NODE(pat_find, NODE_PAT_FIND);
  n->pre = pre;
  n->elems = elems;
  n->post = post;
  return (node*)n;
}

/* Create hash pattern node {a:, b: x, **rest} */
static node*
new_pat_hash(parser_state *p, node *pairs, node *rest)
{
  struct mrb_ast_pat_hash_node *n = NEW_NODE(pat_hash, NODE_PAT_HASH);
  n->pairs = pairs;
  n->rest = rest;
  return (node*)n;
}

/* Create one-line pattern matching node (expr in pattern / expr => pattern) */
static node*
new_match_pat(parser_state *p, node *value, node *pattern, mrb_bool raise_on_fail)
{
  struct mrb_ast_match_pat_node *n = NEW_NODE(match_pat, NODE_MATCH_PAT);
  n->value = value;
  n->pattern = pattern;
  n->raise_on_fail = raise_on_fail;
  return (node*)n;
}

/* Create in-clause node for case/in */
static node*
new_in(parser_state *p, node *pattern, node *guard, node *body, mrb_bool guard_is_unless)
{
  struct mrb_ast_in_node *n = NEW_NODE(in, NODE_IN);
  n->pattern = pattern;
  n->guard = guard;
  n->body = body;
  n->guard_is_unless = guard_is_unless;
  return (node*)n;
}

/* struct: postexe_node(body) */
static node*
new_postexe(parser_state *p, node *a)
{
  struct mrb_ast_postexe_node *postexe_node = NEW_NODE(postexe, NODE_POSTEXE);
  postexe_node->body = a;
  return (node*)postexe_node;
}

/* struct: self_node() */
static node*
new_self(parser_state *p)
{
  struct mrb_ast_self_node *n = NEW_NODE(self, NODE_SELF);

  return (node*)n;
}

/* struct: call_node(receiver, method, args) */
static node*
new_call(parser_state *p, node *receiver, mrb_sym method, node *args, int pass)
{
  /* Calculate size needed (fixed size now) */  struct mrb_ast_call_node *n = NEW_NODE(call, NODE_CALL);
  n->receiver = receiver;
  n->method_name = method;
  n->safe_call = (pass == 0); /* pass == 0 means safe call (&.) */

  /* Store args pointer directly - no need to unpack and repack */
  n->args = args;

  void_expr_error(p, receiver);
  return (node*)n;
}

/* struct: fcall_node(method, args) */
static node*
new_fcall(parser_state *p, mrb_sym b, node *c)
{
  return new_call(p, NULL, b, c, '.');
}

/* (a b . c) */
static node*
new_callargs(parser_state *p, node *a, node *b, node *c)
{
  /* Allocate struct mrb_ast_callargs (fixed size, like new_args) */
  struct mrb_ast_callargs *callargs = (struct mrb_ast_callargs*)parser_palloc(p, sizeof(struct mrb_ast_callargs));

  /* Initialize members directly */
  callargs->regular_args = a;   /* Cons list of regular arguments (preserves splat compatibility) */
  callargs->keyword_args = b;   /* Keyword arguments hash node */
  callargs->block_arg = c;      /* Block argument node */

  /* Return direct cast to node (like new_args) */
  return (node*)callargs;
}

/* struct: super_node(args) */
static node*
new_super(parser_state *p, node *c)
{
  struct mrb_ast_super_node *n = NEW_NODE(super, NODE_SUPER);
  n->args = c;

  return (node*)n;
}

/* struct: zsuper_node() */
static node*
new_zsuper(parser_state *p)
{
  struct mrb_ast_super_node *n = NEW_NODE(super, NODE_ZSUPER);
  n->args = NULL;  /* zsuper initially has no args, but may be added by call_with_block */
  return (node*)n;
}

/* struct: yield_node(args) */
static node*
new_yield(parser_state *p, node *c)
{
  /* Handle callargs structure - direct casting like new_args() */
  if (c) {
    struct mrb_ast_callargs *callargs = (struct mrb_ast_callargs*)c;
    if (callargs->block_arg) {
      yyerror(NULL, p, "both block arg and actual block given");
    }
  }  struct mrb_ast_yield_node *n = NEW_NODE(yield, NODE_YIELD);
  n->args = c;

  return (node*)n;
}

/* struct: return_node(value) */
static node*
new_return(parser_state *p, node *c)
{
  struct mrb_ast_return_node *n = NEW_NODE(return, NODE_RETURN);
  n->args = c;

  return (node*)n;
}

/* struct: break_node(value) */
static node*
new_break(parser_state *p, node *c)
{
  struct mrb_ast_break_node *n = NEW_NODE(break, NODE_BREAK);
  n->value = c;
  return (node*)n;
}

/* struct: next_node(value) */
static node*
new_next(parser_state *p, node *c)
{
  struct mrb_ast_next_node *n = NEW_NODE(next, NODE_NEXT);
  n->value = c;
  return (node*)n;
}

/* struct: redo_node() */
static node*
new_redo(parser_state *p)
{
  struct mrb_ast_redo_node *n = NEW_NODE(redo, NODE_REDO);
  return (node*)n;
}

/* struct: retry_node() */
static node*
new_retry(parser_state *p)
{
  struct mrb_ast_retry_node *n = NEW_NODE(retry, NODE_RETRY);
  return (node*)n;
}

/* struct: dot2_node(beg, end) */
static node*
new_dot2(parser_state *p, node *a, node *b)
{
  struct mrb_ast_dot2_node *n = NEW_NODE(dot2, NODE_DOT2);
  n->left = a;
  n->right = b;

  return (node*)n;
}

/* struct: dot3_node(beg, end) */
static node*
new_dot3(parser_state *p, node *a, node *b)
{
  struct mrb_ast_dot3_node *n = NEW_NODE(dot3, NODE_DOT3);
  n->left = a;
  n->right = b;

  return (node*)n;
}

/* struct: colon2_node(base, name) */
static node*
new_colon2(parser_state *p, node *b, mrb_sym c)
{
  void_expr_error(p, b);

  struct mrb_ast_colon2_node *colon2_node = NEW_NODE(colon2, NODE_COLON2);
  colon2_node->base = b;
  colon2_node->name = c;
  return (node*)colon2_node;
}

/* struct: colon3_node(name) */
static node*
new_colon3(parser_state *p, mrb_sym c)
{
  struct mrb_ast_colon3_node *colon3_node = NEW_NODE(colon3, NODE_COLON3);
  colon3_node->name = c;
  return (node*)colon3_node;
}

/* struct: and_node(left, right) */
static node*
new_and(parser_state *p, node *a, node *b)
{
  void_expr_error(p, a);

  struct mrb_ast_and_node *n = NEW_NODE(and, NODE_AND);
  n->left = a;
  n->right = b;

  return (node*)n;
}

/* struct: or_node(left, right) */
static node*
new_or(parser_state *p, node *a, node *b)
{
  void_expr_error(p, a);

  struct mrb_ast_or_node *n = NEW_NODE(or, NODE_OR);
  n->left = a;
  n->right = b;

  return (node*)n;
}

/* struct: array_node(elements) - uses cons list */
static node*
new_array(parser_state *p, node *a)
{
  struct mrb_ast_array_node *n = NEW_NODE(array, NODE_ARRAY);
  n->elements = a;

  return (node*)n;
}

/* struct: splat_node(value) */
static node*
new_splat(parser_state *p, node *a)
{
  void_expr_error(p, a);

  struct mrb_ast_splat_node *splat_node = NEW_NODE(splat, NODE_SPLAT);
  splat_node->value = a;
  return (node*)splat_node;
}

/* struct: hash_node(pairs) - uses cons list */
static node*
new_hash(parser_state *p, node *a)
{
  struct mrb_ast_hash_node *n = NEW_NODE(hash, NODE_HASH);
  n->pairs = a;

  return (node*)n;
}

/* (:sym . a) */
/* Symbol node creation - supports both variable and legacy modes */
static node*
new_sym(parser_state *p, mrb_sym sym)
{
  struct mrb_ast_sym_node *n = NEW_NODE(sym, NODE_SYM);
  n->symbol = sym;

  return (node*)n;
}

static node*
new_xvar(parser_state *p, mrb_sym sym, enum node_type type)
{
  struct mrb_ast_var_node *n = NEW_NODE(var, type);
  n->symbol = sym;

  return (node*)n;
}

#define new_lvar(p, sym) new_xvar(p, sym, NODE_LVAR)
#define new_ivar(p, sym) new_xvar(p, sym, NODE_IVAR)
#define new_gvar(p, sym) new_xvar(p, sym, NODE_GVAR)
#define new_cvar(p, sym) new_xvar(p, sym, NODE_CVAR)

static mrb_sym
new_strsym(parser_state *p, node* str)
{
  size_t len = (size_t)str->car;
  const char *s = (const char*)str->cdr;

  return mrb_intern(p->mrb, s, len);
}

/* (:nvar . a) */
static node*
new_nvar(parser_state *p, int num)
{
  int nvar;
  node *nvars = p->nvars->cdr;
  while (nvars) {
    nvar = node_to_int(nvars->car);
    if (nvar == -2) break; /* top of the scope */
    if (nvar > 0) {
      yyerror(NULL, p, "numbered parameter used in outer block");
      break;
    }
    nvars->car = int_to_node(-1);
    nvars = nvars->cdr;
  }
  nvar = node_to_int(p->nvars->car);
  if (nvar == -1) {
    yyerror(NULL, p, "numbered parameter used in inner block");
  }
  else {
    p->nvars->car = int_to_node(nvar > num ? nvar : num);
  }
  struct mrb_ast_nvar_node *n = NEW_NODE(nvar, NODE_NVAR);
  n->num = num;
  return (node*)n;
}

/* struct: const_node(name) */
static node*
new_const(parser_state *p, mrb_sym sym)
{
  struct mrb_ast_const_node *n = NEW_NODE(const, NODE_CONST);
  n->symbol = sym;

  return (node*)n;
}

/* struct: undef_node(syms) - uses cons list */
static node*
new_undef(parser_state *p, node *syms)
{
  struct mrb_ast_undef_node *undef_node = NEW_NODE(undef, NODE_UNDEF);
  undef_node->syms = syms;
  return (node*)undef_node;
}

/* struct: class_node(path, super, body) */
static node*
new_class(parser_state *p, node *c, node *s, node *b)
{
  void_expr_error(p, s);

  struct mrb_ast_class_node *n = NEW_NODE(class, NODE_CLASS);
  n->name = c;
  n->superclass = s;
  n->body = cons(locals_node(p), b);

  return (node*)n;
}

/* struct: sclass_node(obj, body) */
static node*
new_sclass(parser_state *p, node *o, node *b)
{
  void_expr_error(p, o);

  struct mrb_ast_sclass_node *n = NEW_NODE(sclass, NODE_SCLASS);
  n->obj = o;
  n->body = cons(locals_node(p), b);

  return (node*)n;
}

/* struct: module_node(path, body) */
static node*
new_module(parser_state *p, node *m, node *b)
{
  struct mrb_ast_module_node *n = NEW_NODE(module, NODE_MODULE);
  n->name = m;
  n->body = cons(locals_node(p), b);

  return (node*)n;
}

/* struct: def_node(name, args, body) */
static node*
new_def(parser_state *p, mrb_sym name)
{
  struct mrb_ast_def_node *n = NEW_NODE(def, NODE_DEF);
  n->name = name;
  n->args = (struct mrb_ast_args *)int_to_node(p->cmdarg_stack);
  n->locals = local_switch(p);
  n->body = NULL;

  return (node*)n;
}

static void
defn_setup(parser_state *p, node *d, node *a, node *b)
{
  struct mrb_ast_def_node *n = def_node(d);
  node *locals = n->locals;

  n->locals = locals_node(p);
  p->cmdarg_stack = node_to_int(n->args);
  n->args = (struct mrb_ast_args *)a;
  n->body = b;
  local_resume(p, locals);
}

/* struct: sdef_node(obj, name, args, body) */
static node*
new_sdef(parser_state *p, node *o, mrb_sym name)
{
  void_expr_error(p, o);

  struct mrb_ast_sdef_node *sdef_node = NEW_NODE(sdef, NODE_SDEF);
  sdef_node->obj = o;
  sdef_node->name = name;
  sdef_node->args = (struct mrb_ast_args *)int_to_node(p->cmdarg_stack);
  sdef_node->locals = local_switch(p);
  sdef_node->body = NULL;
  return (node*)sdef_node;
}

static void
local_add_margs(parser_state *p, node *n)
{
  while (n) {
    if (node_type(n->car) == NODE_MARG) {
      struct mrb_ast_masgn_node *masgn_n = (struct mrb_ast_masgn_node*)n->car;
      node *rhs = masgn_n->rhs;

      /* For parameter destructuring, rhs contains the locals */
      if (rhs) {
        node *t = rhs;
        while (t) {
          local_add_f(p, node_to_sym(t->car));
          t = t->cdr;
        }
        /* Clear cons list RHS immediately after use */
        masgn_n->rhs = NULL;
      }

      /* Process nested destructuring in lhs components */
      if (masgn_n->pre) {
        local_add_margs(p, masgn_n->pre);
      }
      if (masgn_n->post) {
        local_add_margs(p, masgn_n->post);
      }
    }
    n = n->cdr;
  }
}


static void
local_add_lv(parser_state *p, node *lv)
{
  while (lv) {
    local_add_f(p, node_to_sym(lv->car));
    lv = lv->cdr;
  }
}

/* (m o r m2 tail) */
/* m: (a b c) */
/* o: ((a . e1) (b . e2)) */
/* r: a */
/* m2: (a b c) */
/* b: a */
static node*
new_args(parser_state *p, node *m, node *opt, mrb_sym rest, node *m2, node *tail)
{
  local_add_margs(p, m);
  local_add_margs(p, m2);

  /* Save original optional arguments before processing */
  node *orig_opt = opt;

  /* Process optional arguments (keep original side effects) */
  while (opt) {
    /* opt: (sym . (opt . lv)) -> (sym . opt) */
    local_add_lv(p, opt->car->cdr->cdr);
    opt->car->cdr = opt->car->cdr->car;
    opt = opt->cdr;
  }

  /* Allocate struct mrb_ast_args (no hdr) */
  struct mrb_ast_args *args = (struct mrb_ast_args*)parser_palloc(p, sizeof(struct mrb_ast_args));

  /* Initialize members */
  args->mandatory_args = m;
  args->optional_args = orig_opt;
  args->rest_arg = rest;
  args->post_mandatory_args = m2;

  /* Deconstruct tail cons list: (kws . (kwrest . blk)) */
  if (tail) {
    args->keyword_args = (node*)tail->car;          /* kws */
    args->kwrest_arg = (mrb_sym)(intptr_t)tail->cdr->car; /* kwrest */
    args->block_arg = (mrb_sym)(intptr_t)tail->cdr->cdr;  /* blk */
    cons_free(tail->cdr);
    cons_free(tail);
  }
  else {
    args->keyword_args = NULL;
    args->kwrest_arg = 0;
    args->block_arg = 0;
  }

  return (node*)args;
}

/* struct: args_tail_node(kwargs, kwrest, block) */
static node*
new_args_tail(parser_state *p, node *kws, mrb_sym kwrest, mrb_sym blk)
{
  node *k;

  if (kws || kwrest) {
    local_add_kw(p, kwrest);
  }

  local_add_blk(p);
  if (blk && blk != MRB_SYM(nil)) local_add_f(p, blk);

  /* allocate register for keywords arguments */
  /* order is for Proc#parameters */
  for (k = kws; k; k = k->cdr) {
    if (!k->car->cdr) { /* allocate required keywords - simplified structure: (key . NULL) */
      local_add_f(p, node_to_sym(k->car->car));
    }
  }
  for (k = kws; k; k = k->cdr) {
    if (k->car->cdr) { /* allocate keywords with default - simplified structure: (key . value) */
      local_add_lv(p, k->car->cdr->cdr);  /* value->cdr for default args */
      k->car->cdr = k->car->cdr->car;    /* value->car for default args */
      local_add_f(p, node_to_sym(k->car->car));
    }
  }

  /* Return cons list: (keyword . (kwrest . blk)) */
  return cons(kws, cons(sym_to_node(kwrest), sym_to_node(blk)));
}

/* (kw_sym . def_arg) - simplified from NODE_KW_ARG wrapper */
static node*
new_kw_arg(parser_state *p, mrb_sym kw, node *def_arg)
{
  mrb_assert(kw);
  return cons(sym_to_node(kw), def_arg);
}

/* (:kw_rest_args . a) */
static node*
new_kw_rest_args(parser_state *p, mrb_sym sym)
{
  return sym_to_node(intern_op(pow));  /* Use ** symbol as direct marker */
}

static node*
new_args_dots(parser_state *p, node *m)
{
  mrb_sym r = intern_op(mul);
  mrb_sym k = intern_op(pow);
  mrb_sym b = intern_op(and);
  local_add_f(p, r);
  return new_args(p, m, 0, r, 0, new_args_tail(p, NULL, k, b));
}

/* struct: block_arg_node(value) */
static node*
new_block_arg(parser_state *p, node *a)
{
  struct mrb_ast_block_arg_node *block_arg_node = NEW_NODE(block_arg, NODE_BLOCK_ARG);
  block_arg_node->value = a;
  return (node*)block_arg_node;
}

static node*
setup_numparams(parser_state *p, node *a)
{
  int nvars = node_to_int(p->nvars->car);
  if (nvars > 0) {
    int i;
    mrb_sym sym;
    // Check if any arguments are already defined
    struct mrb_ast_args *args = (struct mrb_ast_args *)a;
    if (a && (args->mandatory_args || args->optional_args || args->rest_arg ||
              args->post_mandatory_args || args->keyword_args || args->kwrest_arg)) {
      yyerror(NULL, p, "ordinary parameter is defined");
    }
    else if (p->locals) {
      /* p->locals should not be NULL unless error happens before the point */
      node* args = 0;
      for (i = nvars; i > 0; i--) {
        char buf[3];

        buf[0] = '_';
        buf[1] = i+'0';
        buf[2] = '\0';
        sym = intern_cstr(buf);
        args = cons(new_lvar(p, sym), args);
        p->locals->car = cons(sym_to_node(sym), p->locals->car);
      }
      a = new_args(p, args, 0, 0, 0, 0);
    }
  }
  return a;
}

/* struct: block_node(args, body) */
static node*
new_block(parser_state *p, node *a, node *b)
{
  a = setup_numparams(p, a);  struct mrb_ast_block_node *n = NEW_NODE(block, NODE_BLOCK);
  n->locals = locals_node(p);
  n->args = (struct mrb_ast_args *)a;
  n->body = b;

  return (node*)n;
}

/* struct: lambda_node(args, body) */
static node*
new_lambda(parser_state *p, node *a, node *b)
{
  a = setup_numparams(p, a);  struct mrb_ast_lambda_node *lambda_node = NEW_NODE(lambda, NODE_LAMBDA);
  lambda_node->locals = locals_node(p);
  lambda_node->args = (struct mrb_ast_args *)a;
  lambda_node->body = b;
  return (node*)lambda_node;
}

/* struct: asgn_node(lhs, rhs) */
static node*
new_asgn(parser_state *p, node *a, node *b)
{
  void_expr_error(p, b);

  struct mrb_ast_asgn_node *n = NEW_NODE(asgn, NODE_ASGN);
  n->lhs = a;
  n->rhs = b;

  return (node*)n;
}

/* Helper function to create MASGN/MARG nodes */
static node*
new_masgn_helper(parser_state *p, node *a, node *b, enum node_type node_type)
{
  struct mrb_ast_masgn_node *n = NEW_NODE(masgn, node_type);

  /* Extract pre, rest, post from cons list structure (a b c) */
  if (a) {
    n->pre = a->car;  /* Pre-splat variables */
    if (a->cdr) {
      n->rest = a->cdr->car;  /* Splat variable (or -1 for anonymous) */
      if (a->cdr->cdr) {
        n->post = a->cdr->cdr->car;  /* Post-splat variables */
        cons_free(a->cdr->cdr);
      }
      else {
        n->post = NULL;
      }
      cons_free(a->cdr);
    }
    else {
      n->rest = NULL;
      n->post = NULL;
    }
    cons_free(a);
  }
  else {
    n->pre = NULL;
    n->rest = NULL;
    n->post = NULL;
  }
  n->rhs = b;

  return (node*)n;
}

/* struct: masgn_node(lhs, rhs) */
static node*
new_masgn(parser_state *p, node *a, node *b)
{
  void_expr_error(p, b);
  return new_masgn_helper(p, a, b, NODE_MASGN);
}

/* (:marg mlhs mrhs) no check - for parameter destructuring */
static node*
new_marg(parser_state *p, node *a)
{
  return new_masgn_helper(p, a, p->locals->car, NODE_MARG);
}

/* struct: op_asgn_node(lhs, op, rhs) */
static node*
new_op_asgn(parser_state *p, node *a, mrb_sym op, node *b)
{
  void_expr_error(p, b);

  struct mrb_ast_op_asgn_node *n = NEW_NODE(op_asgn, NODE_OP_ASGN);
  n->lhs = a;
  n->op = op;
  n->rhs = b;
  return (node*)n;
}

static node*
new_int_n(parser_state *p, int32_t val)
{
  struct mrb_ast_int_node *n = NEW_NODE(int, NODE_INT);
  n->value = val;

  return (node*)n;
}

static node*
new_imaginary(parser_state *p, node *imaginary)
{
  return new_fcall(p, MRB_SYM(Complex),
                   new_callargs(p, list2(new_int_n(p, 0), imaginary), 0, 0));
}

static node*
new_rational(parser_state *p, node *rational)
{
  return new_fcall(p, MRB_SYM(Rational), new_callargs(p, list1(rational), 0, 0));
}

/* Read integer into int32_t with overflow detection */
static mrb_bool
read_int32(const char *p, int base, int32_t *result)
{
  const char *e = p + strlen(p);
  int32_t value = 0;
  mrb_bool neg = FALSE;

  if (base < 2 || base > 16) {
    return FALSE;
  }

  if (*p == '+') {
    p++;
  }
  else if (*p == '-') {
    neg = TRUE;
    p++;
  }

  while (p < e) {
    int n;
    char c = *p;

    /* Skip underscores */
    if (c == '_') {
      p++;
      continue;
    }

    /* Parse digit */
    if (c >= '0' && c <= '9') {
      n = c - '0';
    }
    else if (c >= 'a' && c <= 'f') {
      n = c - 'a' + 10;
    }
    else if (c >= 'A' && c <= 'F') {
      n = c - 'A' + 10;
    }
    else {
      /* Invalid character */
      return FALSE;
    }

    if (n >= base) {
      /* Digit not valid for this base */
      return FALSE;
    }

    /* Check for multiplication overflow */
    if (value > INT32_MAX / base) {
      return FALSE;
    }

    value *= base;

    /* Check for addition overflow */
    if (value > INT32_MAX - n) {
      /* Special case: -INT32_MIN is valid */
      if (neg && value == (INT32_MAX - n + 1) && p + 1 == e) {
        *result = INT32_MIN;
        return TRUE;
      }
      return FALSE;
    }

    value += n;
    p++;
  }

  *result = neg ? -value : value;
  return TRUE;
}

static node*
new_int(parser_state *p, const char *s, int base, int suffix)
{
  int32_t val;
  node* result;

  /* Try to parse as int32_t first */
  if (read_int32(s, base, &val)) {
    result = new_int_n(p, val);
  }
  else {
    /* Big integer - create NODE_BIGINT */
    struct mrb_ast_bigint_node *n = NEW_NODE(bigint, NODE_BIGINT);
    n->string = strdup(s);
    n->base = base;

    result = (node*)n;
  }

  /* Handle suffix modifiers */
  if (suffix & NUM_SUFFIX_R) {
    result = new_rational(p, result);
  }
  if (suffix & NUM_SUFFIX_I) {
    result = new_imaginary(p, result);
  }

  return result;
}

#ifndef MRB_NO_FLOAT
/* struct: float_node(value) */
static node*
new_float(parser_state *p, const char *s, int suffix)
{
  struct mrb_ast_float_node *n = NEW_NODE(float, NODE_FLOAT);
  n->value = strdup(s);

  node* result = (node*)n;

  if (suffix & NUM_SUFFIX_R) {
    result = new_rational(p, result);
  }
  if (suffix & NUM_SUFFIX_I) {
    result = new_imaginary(p, result);
  }
  return result;
}
#endif

/* Create string node from cons list */
/* struct: str_node(str) */
static node*
new_str(parser_state *p, node *a)
{
  struct mrb_ast_str_node *n = NEW_NODE(str, NODE_STR);
  n->list = a;

  return (node*)n;
}

/* struct: xstr_node(str) */
static node*
new_xstr(parser_state *p, node *a)
{
  struct mrb_ast_xstr_node *n = NEW_NODE(xstr, NODE_XSTR);
  n->list = a;
  return (node*)n;
}

/* struct: dsym_node(parts) - uses cons list */
static node*
new_dsym(parser_state *p, node *a)
{
  struct mrb_ast_str_node *n = NEW_NODE(str, NODE_DSYM);
  n->list = a;
  return (node*)n;
}

/* struct: regx_node(pattern, flags, encoding) */
static node*
new_regx(parser_state *p, node *list, const char *flags, const char *encoding)
{
  struct mrb_ast_regx_node *n = NEW_NODE(regx, NODE_REGX);
  n->list = list;
  n->flags = flags;
  n->encoding = encoding;
  return (node*)n;
}

/* struct: back_ref_node(n) */
static node*
new_back_ref(parser_state *p, int n)
{
  struct mrb_ast_back_ref_node *backref_node = NEW_NODE(back_ref, NODE_BACK_REF);
  backref_node->type = n;
  return (node*)backref_node;
}

/* struct: nth_ref_node(n) */
static node*
new_nth_ref(parser_state *p, int n)
{
  struct mrb_ast_nth_ref_node *nthref_node = NEW_NODE(nth_ref, NODE_NTH_REF);
  nthref_node->nth = n;
  return (node*)nthref_node;
}

/* struct: heredoc_node(str) */
static node*
new_heredoc(parser_state *p, struct mrb_parser_heredoc_info **infop)
{
  struct mrb_ast_heredoc_node *n = NEW_NODE(heredoc, NODE_HEREDOC);

  /* Initialize embedded heredoc info struct */
  n->info.allow_indent = FALSE;
  n->info.remove_indent = FALSE;
  n->info.line_head = FALSE;
  n->info.indent = 0;
  n->info.indented = NULL;
  n->info.type = str_not_parsing;  // Will be set by heredoc processing
  n->info.term = NULL;  // Will be set by heredoc processing
  n->info.term_len = 0;
  n->info.doc = NULL;

  /* Return pointer to embedded info if requested */
  *infop = &n->info;

  return (node*)n;
}

static void
new_bv(parser_state *p, mrb_sym id)
{
}

static node*
new_literal_delim(parser_state *p)
{
  return cons((node*)0, (node*)0);
}

/* Helper for creating string representation cons (length . string_ptr) */
static node*
new_str_rep(parser_state *p, const char *str, int len)
{
  return cons(int_to_node(len), (node*)strndup(str, len));
}

/* Helper for creating string representation from current token */
static node*
new_str_tok(parser_state *p)
{
  return new_str_rep(p, tok(p), toklen(p));
}

/* Helper for creating empty string representation */
static node*
new_str_empty(parser_state *p)
{
  return new_str_rep(p, "", 0);
}

/* (:words . a) */
static node*
new_words(parser_state *p, node *a)
{
  struct mrb_ast_words_node *words_node = NEW_NODE(words, NODE_WORDS);
  words_node->args = a;
  return (node*)words_node;
}

/* (:symbols . a) */
static node*
new_symbols(parser_state *p, node *a)
{
  struct mrb_ast_symbols_node *symbols_node = NEW_NODE(symbols, NODE_SYMBOLS);
  symbols_node->args = a;
  return (node*)symbols_node;
}

/* xxx ----------------------------- */

/* (:call a op) */
static node*
call_uni_op(parser_state *p, node *recv, const char *m)
{
  void_expr_error(p, recv);
  return new_call(p, recv, intern_cstr(m), 0, '.');
}

/* (:call a op b) */
static node*
call_bin_op(parser_state *p, node *recv, const char *m, node *arg1)
{
  return new_call(p, recv, intern_cstr(m), new_callargs(p, list1(arg1), 0, 0), '.');
}

static void
args_with_block(parser_state *p, node *a, node *b)
{
  if (b) {
    /* Handle callargs structure - direct casting like new_args() */
    struct mrb_ast_callargs *callargs = (struct mrb_ast_callargs*)a;
    if (callargs->block_arg) {
      yyerror(NULL, p, "both block arg and actual block given");
    }
    callargs->block_arg = b;
  }
}

static void
endless_method_name(parser_state *p, node *defn)
{
  struct mrb_ast_def_node *def = (struct mrb_ast_def_node*)defn;
  mrb_sym sym = def->name;
  mrb_int len;
  const char *name = mrb_sym_name_len(p->mrb, sym, &len);

  if (len > 1 && name[len-1] == '=') {
    for (int i=0; i<len-1; i++) {
      if (!identchar(name[i])) return;
    }
    yyerror(NULL, p, "setter method cannot be defined by endless method definition");
  }
}

static void
call_with_block(parser_state *p, node *a, node *b)
{
  if (!a) return;

  /* Handle direct variable-sized nodes */
  struct mrb_ast_var_header *header = (struct mrb_ast_var_header*)a;

  enum node_type var_type = (enum node_type)header->node_type;
  switch (var_type) {
  case NODE_SUPER:
  case NODE_ZSUPER:
    /* For variable-sized super/zsuper nodes, update the args field directly */
    {
      struct mrb_ast_super_node *super_n = super_node(a);
      if (!super_n->args) {
        super_n->args = new_callargs(p, 0, 0, b);
      }
      else {
        args_with_block(p, super_n->args, b);
      }
    }
    break;
  case NODE_YIELD:
    /* Variable-sized yield nodes should generate an error when given a block */
    yyerror(NULL, p, "block given to yield");
    break;
  case NODE_RETURN:
    /* Variable-sized return nodes - recursively call with args */
    {
      struct mrb_ast_return_node *return_n = return_node(a);
      if (return_n->args != NULL) {
        call_with_block(p, return_n->args, b);
      }
    }
    break;
  case NODE_BREAK:
    /* Variable-sized break nodes - recursively call with value */
    {
      struct mrb_ast_break_node *break_n = (struct mrb_ast_break_node*)a;
      if (break_n->value != NULL) {
        call_with_block(p, break_n->value, b);
      }
    }
    break;
  case NODE_NEXT:
    /* Variable-sized next nodes - recursively call with value */
    {
      struct mrb_ast_next_node *next_n = (struct mrb_ast_next_node*)a;
      if (next_n->value != NULL) {
        call_with_block(p, next_n->value, b);
      }
    }
    break;
  case NODE_CALL:
    /* Variable-sized call nodes - add block to existing args */
    {
      struct mrb_ast_call_node *call = call_node(a);

      if (call->args && callargs_node(call->args)->block_arg) {
        yyerror(NULL, p, "both block arg and actual block given");
        return;
      }

      /* Use existing args and add block */
      if (call->args) {
        /* Modify existing callargs structure to add block */
        args_with_block(p, call->args, b);
      }
      else {
        /* Create new callargs with just the block */
        call->args = new_callargs(p, NULL, NULL, b);
      }
    }
    break;
  default:
    /* For other variable-sized nodes, do nothing */
    break;
  }
}

static node*
new_negate(parser_state *p, node *n)
{
  struct mrb_ast_negate_node *negate_node = NEW_NODE(negate, NODE_NEGATE);
  negate_node->operand = n;
  return (node*)negate_node;
}

static node*
cond(node *n)
{
  return n;
}

static node*
ret_args(parser_state *p, node *n)
{
  /* Handle callargs structure - direct casting like new_args() */
  struct mrb_ast_callargs *callargs = (struct mrb_ast_callargs*)n;
  if (callargs->block_arg) {
    yyerror(NULL, p, "block argument should not be given");
    return NULL;
  }
  if (!callargs->regular_args) return NULL;
  if (!callargs->regular_args->cdr) return callargs->regular_args->car;
  return new_array(p, callargs->regular_args);
}

static void
assignable(parser_state *p, node *lhs)
{
  switch (node_type(lhs)) {
  case NODE_LVAR:
    local_add(p, var_node(lhs)->symbol);
    break;
  case NODE_CONST:
    if (p->in_def)
      yyerror(NULL, p, "dynamic constant assignment");
    break;
  default:
    /* Other node types don't need special handling in assignable */
    break;
  }
}

static node*
var_reference(parser_state *p, node *lhs)
{
  /* Check if this is a variable-sized node */
  if (node_type_p(lhs, NODE_LVAR)) {
    mrb_sym sym = var_node(lhs)->symbol;
    if (!local_var_p(p, sym)) {
      node *n = new_fcall(p, sym, 0);
      /* Don't free variable-sized nodes - they're managed by the parser allocator */
      return n;
    }
  }
  return lhs;
}

static node*
label_reference(parser_state *p, mrb_sym sym)
{
  const char *name = mrb_sym_name(p->mrb, sym);

  if (local_var_p(p, sym)) {
    return new_lvar(p, sym);
  }
  else if (ISUPPER(name[0])) {
    return new_const(p, sym);
  }
  else {
    return new_fcall(p, sym, 0);
  }
}

typedef enum mrb_string_type  string_type;

typedef struct parser_lex_strterm {
  int type;
  int level;
  int term;
  int paren;
  struct parser_lex_strterm *prev;
} parser_lex_strterm;

static parser_lex_strterm*
new_strterm(parser_state *p, string_type type, int term, int paren)
{
  parser_lex_strterm *lex = (parser_lex_strterm*)parser_palloc(p, sizeof(parser_lex_strterm));
  lex->type = type;
  lex->level = 0;
  lex->term = term;
  lex->paren = paren;
  lex->prev = p->lex_strterm;
  return lex;
}

static void
end_strterm(parser_state *p)
{
  parser_lex_strterm *term = p->lex_strterm->prev;
  parser_pfree(p->lex_strterm);
  p->lex_strterm = term;
}

static node*
push_strterm(parser_state *p)
{
  node *n = cons((node*)p->lex_strterm, p->parsing_heredoc);
  p->lex_strterm = NULL;
  return n;
}

static void
pop_strterm(parser_state *p, node *n)
{
  p->lex_strterm = (parser_lex_strterm*)n->car;
  p->parsing_heredoc = n->cdr;
  cons_free(n);
}

static parser_heredoc_info *
parsing_heredoc_info(parser_state *p)
{
  node *nd = p->parsing_heredoc;
  if (nd == NULL) return NULL;
  /* mrb_assert(nd->car->car == NODE_HEREDOC); */
  if (node_type(nd->car) == NODE_HEREDOC) {
    /* Variable-sized heredoc node - return address of embedded info struct */
    struct mrb_ast_heredoc_node *heredoc = (struct mrb_ast_heredoc_node*)nd->car;
    return &heredoc->info;
  }
  return (parser_heredoc_info*)nd->car->cdr;
}

static void
heredoc_treat_nextline(parser_state *p)
{
  if (p->heredocs_from_nextline == NULL) return;
  if (p->parsing_heredoc && p->lex_strterm) {
    append(p->heredocs_from_nextline, p->parsing_heredoc);
  }
  p->parsing_heredoc = p->heredocs_from_nextline;
  p->lex_strterm = new_strterm(p, parsing_heredoc_info(p)->type, 0, 0);
  p->heredocs_from_nextline = NULL;
}

static void
heredoc_end(parser_state *p)
{
  p->parsing_heredoc = p->parsing_heredoc->cdr;
  if (p->parsing_heredoc == NULL) {
    p->lstate = EXPR_BEG;
    end_strterm(p);
  }
  else {
    /* next heredoc */
    p->lex_strterm->type = parsing_heredoc_info(p)->type;
  }
}
#define is_strterm_type(p,str_func) ((p)->lex_strterm->type & (str_func))

static void
prohibit_literals(parser_state *p, node *n)
{
  if (n == 0) {
    yyerror(NULL, p, "can't define singleton method for ().");
  }
  else {
    enum node_type nt = node_type(n);
    switch (nt) {
    case NODE_INT:
    case NODE_STR:
    case NODE_XSTR:
    case NODE_REGX:
    case NODE_FLOAT:
    case NODE_ARRAY:
    case NODE_HEREDOC:
      yyerror(NULL, p, "can't define singleton method for literals");
    default:
      break;
    }
  }
}

/* xxx ----------------------------- */

%}

%define parse.error verbose
%define api.pure
%parse-param {parser_state *p}
%lex-param {parser_state *p}

%union {
    node *nd;
    mrb_sym id;
    int num;
    stack_type stack;
    const struct vtable *vars;
}

%token <num>
        keyword_class   "'class'"
        keyword_module  "'module'"
        keyword_def     "'def'"
        keyword_begin   "'begin'"
        keyword_if      "'if'"
        keyword_unless  "'unless'"
        keyword_while   "'while'"
        keyword_until   "'until'"
        keyword_for     "'for'"

%token
        keyword_undef   "'undef'"
        keyword_rescue  "'rescue'"
        keyword_ensure  "'ensure'"
        keyword_end     "'end'"
        keyword_then    "'then'"
        keyword_elsif   "'elsif'"
        keyword_else    "'else'"
        keyword_case    "'case'"
        keyword_when    "'when'"
        keyword_break   "'break'"
        keyword_next    "'next'"
        keyword_redo    "'redo'"
        keyword_retry   "'retry'"
        keyword_in      "'in'"
        keyword_do      "'do'"
        keyword_do_cond         "'do' for condition"
        keyword_do_block        "'do' for block"
        keyword_do_LAMBDA       "'do' for lambda"
        keyword_return  "'return'"
        keyword_yield   "'yield'"
        keyword_super   "'super'"
        keyword_self    "'self'"
        keyword_nil     "'nil'"
        keyword_true    "'true'"
        keyword_false   "'false'"
        keyword_and     "'and'"
        keyword_or      "'or'"
        keyword_not     "'not'"
        modifier_if     "'if' modifier"
        modifier_unless "'unless' modifier"
        modifier_while  "'while' modifier"
        modifier_until  "'until' modifier"
        modifier_rescue "'rescue' modifier"
        keyword_alias   "'alias'"
        keyword_BEGIN   "'BEGIN'"
        keyword_END     "'END'"
        keyword__LINE__ "'__LINE__'"
        keyword__FILE__ "'__FILE__'"
        keyword__ENCODING__     "'__ENCODING__'"

%token <id>  tIDENTIFIER "local variable or method"
%token <id>  tFID "method"
%token <id>  tGVAR "global variable"
%token <id>  tIVAR "instance variable"
%token <id>  tCONSTANT "constant"
%token <id>  tCVAR "class variable"
%token <id>  tLABEL_TAG "label"
%token <nd>  tINTEGER "integer literal"
%token <nd>  tFLOAT "float literal"
%token <nd>  tCHAR "character literal"
%token <nd>  tXSTRING tREGEXP
%token <nd>  tSTRING tSTRING_PART tSTRING_MID
%token <nd>  tNTH_REF tBACK_REF
%token <num> tREGEXP_END
%token <num> tNUMPARAM "numbered parameter"

%type <nd> singleton string string_fragment string_rep string_interp xstring regexp
%type <nd> literal numeric cpath symbol defn_head defs_head
%type <nd> top_compstmt top_stmts top_stmt
%type <nd> bodystmt compstmt stmts stmt expr arg primary command command_call method_call
%type <nd> expr_value arg_rhs primary_value
%type <nd> if_tail opt_else case_body cases opt_rescue exc_list exc_var opt_ensure
%type <nd> args call_args opt_call_args
%type <nd> paren_args opt_paren_args variable
%type <nd> command_args aref_args opt_block_arg block_arg var_ref var_lhs
%type <nd> command_asgn command_rhs mrhs superclass block_call block_command
%type <nd> f_block_optarg f_block_opt
%type <nd> f_opt_arglist_paren f_arglist_paren f_arglist
%type <nd> f_args f_arg f_arg_item f_optarg f_margs
%type <nd> assoc_list assocs assoc undef_list backref for_var
%type <nd> block_param opt_block_param block_param_def f_opt
%type <nd> bv_decls opt_bv_decl bvar f_larglist lambda_body
%type <nd> brace_block cmd_brace_block do_block lhs none f_bad_arg
%type <nd> mlhs mlhs_list mlhs_post mlhs_basic mlhs_item mlhs_node mlhs_inner
%type <id> fsym sym basic_symbol operation operation2 operation3
%type <id> cname fname op f_rest_arg f_block_arg opt_f_block_arg f_norm_arg f_opt_asgn
%type <nd> heredoc words symbols
%type <num> call_op call_op2     /* 0:'&.', 1:'.', 2:'::' */

%type <nd> args_tail opt_args_tail f_kwarg f_kw
%type <nd> f_block_kwarg f_block_kw block_args_tail opt_block_args_tail
%type <id> f_label f_kwrest

/* pattern matching */
%type <nd> in_clauses p_expr p_alt p_value p_var p_as p_array p_array_body p_array_elems p_rest p_hash p_hash_body p_hash_elems p_hash_elem p_kwrest p_args_head p_args_post p_const

%token tUPLUS             "unary plus"
%token tUMINUS            "unary minus"
%token tCMP               "<=>"
%token tEQ                "=="
%token tEQQ               "==="
%token tNEQ               "!="
%token tGEQ               ">="
%token tLEQ               "<="
%token tANDOP             "&&"
%token tOROP              "||"
%token tMATCH             "=~"
%token tNMATCH            "!~"
%token tDOT2              ".."
%token tDOT3              "..."
%token tBDOT2 tBDOT3      /* (.. and (... */
%token tAREF tASET        /* [] and []= */
%token tLSHFT             "<<"
%token tRSHFT             ">>"
%token tCOLON2            "::"
%token tCOLON3            /* :: at EXPR_BEG */
%token <id> tOP_ASGN      /* +=, -=  etc. */
%token tASSOC             "=>"
%token tLPAREN tLPAREN_ARG "("
%token tRPAREN            ")"
%token tLBRACK            "["
%token tLBRACE tLBRACE_ARG "{"
%token tSTAR              "*"
%token tPOW tDSTAR        "**"
%token tAMPER             "&"
%token tLAMBDA            "->"
%token tANDDOT            "&."
%token tSYMBEG "symbol"
%token tSTRING_BEG "string literal"
%token tXSTRING_BEG tSTRING_DVAR tREGEXP_BEG tWORDS_BEG tSYMBOLS_BEG tLAMBEG
%token <nd> tHEREDOC_BEG  "here document"
%token tHEREDOC_END tLITERAL_DELIM tHD_LITERAL_DELIM
%token <nd> tHD_STRING_PART tHD_STRING_MID

/*
 * precedence table
 */

%nonassoc tLOWEST
%nonassoc tLBRACE_ARG

%nonassoc  modifier_if modifier_unless modifier_while modifier_until keyword_in
%left  keyword_or keyword_and
%right keyword_not
%right '=' tOP_ASGN
%left modifier_rescue
%right '?' ':' tLABEL_TAG
%nonassoc tDOT2 tDOT3 tBDOT2 tBDOT3
%left  tOROP
%left  tANDOP
%nonassoc  tCMP tEQ tEQQ tNEQ tMATCH tNMATCH
%left  '>' tGEQ '<' tLEQ
%left  '|' '^'
%left  '&'
%left  tLSHFT tRSHFT
%left  '+' '-'
%left  '*' '/' '%'
%right tUMINUS_NUM tUMINUS
%right tPOW
%right '!' '~' tUPLUS

%token tLAST_TOKEN

%%
program         :   {
                      p->lstate = EXPR_BEG;
                      if (!p->locals) p->locals = cons(0,0);
                    }
                  top_compstmt
                    {
                      p->tree = new_scope(p, $2);
                    }
                ;

top_compstmt    : top_stmts opt_terms
                    {
                      $$ = $1;
                    }
                ;

top_stmts       : none
                    {
                      $$ = new_stmts(p, 0);
                    }
                | top_stmt
                    {
                      $$ = new_stmts(p, $1);
                    }
                | top_stmts terms top_stmt
                    {
                      $$ = stmts_push(p, $1, newline_node($3));
                    }
                | error top_stmt
                    {
                      $$ = new_stmts(p, 0);
                    }
                ;

top_stmt        : stmt
                | keyword_BEGIN
                    {
                      $<nd>$ = local_switch(p);
                      nvars_block(p);
                    }
                  '{' top_compstmt '}'
                    {
                      yyerror(&@1, p, "BEGIN not supported");
                      local_resume(p, $<nd>2);
                      nvars_unnest(p);
                      $$ = 0;
                    }
                ;

bodystmt        : compstmt
                  opt_rescue
                  opt_else
                  opt_ensure
                    {
                      if ($2) {
                        $$ = new_rescue(p, $1, $2, $3);
                      }
                      else if ($3) {
                        yywarning(p, "else without rescue is useless");
                        $$ = stmts_push(p, $1, $3);
                      }
                      else {
                        $$ = $1;
                      }
                      if ($4) {
                        if ($$) {
                          $$ = new_ensure(p, $$, $4);
                        }
                        else {
                          $$ = push($4, new_nil(p));
                        }
                      }
                    }
                ;

compstmt        : stmts opt_terms
                    {
                      $$ = $1;
                    }
                ;

stmts           : none
                    {
                      $$ = new_stmts(p, 0);
                    }
                | stmt
                    {
                      $$ = new_stmts(p, $1);
                    }
                | stmts terms stmt
                    {
                      $$ = stmts_push(p, $1, newline_node($3));
                    }
                | error stmt
                    {
                      $$ = new_stmts(p, $2);
                    }
                ;

stmt            : keyword_alias fsym {p->lstate = EXPR_FNAME;} fsym
                    {
                      $$ = new_alias(p, $2, $4);
                    }
                | keyword_undef undef_list
                    {
                      $$ = new_undef(p, $2);
                    }
                | stmt modifier_if expr_value
                    {
                      $$ = new_if(p, cond($3), $1, 0);
                    }
                | stmt modifier_unless expr_value
                    {
                      $$ = new_if(p, cond($3), 0, $1);
                    }
                | stmt modifier_while expr_value
                    {
                      if ($1 && node_type_p($1, NODE_BEGIN)) {
                        $$ = new_while_mod(p, cond($3), $1);
                      }
                      else {
                        $$ = new_while(p, cond($3), $1);
                      }
                    }
                | stmt modifier_until expr_value
                    {
                      if ($1 && node_type_p($1, NODE_BEGIN)) {
                        $$ = new_until_mod(p, cond($3), $1);
                      }
                      else {
                        $$ = new_until(p, cond($3), $1);
                      }
                    }
                | stmt modifier_rescue stmt
                    {
                      $$ = new_mod_rescue(p, $1, $3);
                    }
                | keyword_END '{' compstmt '}'
                    {
                      yyerror(&@1, p, "END not supported");
                      $$ = new_postexe(p, $3);
                    }
                | command_asgn
                | mlhs '=' command_call
                    {
                      $$ = new_masgn(p, $1, $3);
                    }
                | lhs '=' mrhs
                    {
                      $$ = new_asgn(p, $1, new_array(p, $3));
                    }
                | mlhs '=' arg
                    {
                      $$ = new_masgn(p, $1, $3);
                    }
                | mlhs '=' mrhs
                    {
                      $$ = new_masgn(p, $1, new_array(p, $3));
                    }
                | expr
                ;

command_asgn    : lhs '=' command_rhs
                    {
                      $$ = new_asgn(p, $1, $3);
                    }
                | var_lhs tOP_ASGN command_rhs
                    {
                      $$ = new_op_asgn(p, $1, $2, $3);
                    }
                | primary_value '[' opt_call_args ']' tOP_ASGN command_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, intern_op(aref), $3, '.'), $5, $6);
                    }
                | primary_value call_op tIDENTIFIER tOP_ASGN command_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, $2), $4, $5);
                    }
                | primary_value call_op tCONSTANT tOP_ASGN command_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, $2), $4, $5);
                    }
                | primary_value tCOLON2 tCONSTANT tOP_ASGN command_call
                    {
                      yyerror(&@1, p, "constant re-assignment");
                      $$ = 0;
                    }
                | primary_value tCOLON2 tIDENTIFIER tOP_ASGN command_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, tCOLON2), $4, $5);
                    }
                | defn_head f_opt_arglist_paren '=' command
                    {
                      $$ = $1;
                      endless_method_name(p, $1);
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, $4);
                      nvars_unnest(p);
                      p->in_def--;
                    }
                | defn_head f_opt_arglist_paren '=' command modifier_rescue arg
                    {
                      $$ = $1;
                      endless_method_name(p, $1);
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, new_mod_rescue(p, $4, $6));
                      nvars_unnest(p);
                      p->in_def--;
                    }
                | defs_head f_opt_arglist_paren '=' command
                    {
                      $$ = $1;
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, $4);
                      nvars_unnest(p);
                      p->in_def--;
                      p->in_single--;
                    }
                | defs_head f_opt_arglist_paren '=' command modifier_rescue arg
                    {
                      $$ = $1;
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, new_mod_rescue(p, $4, $6));
                      nvars_unnest(p);
                      p->in_def--;
                      p->in_single--;
                    }
                | backref tOP_ASGN command_rhs
                    {
                      backref_error(p, $1);
                      $$ = new_stmts(p, 0);
                    }
                ;

command_rhs     : command_call   %prec tOP_ASGN
                | command_call modifier_rescue stmt
                    {
                      $$ = new_mod_rescue(p, $1, $3);
                    }
                | command_asgn
                ;

expr            : command_call
                | expr keyword_and expr
                    {
                      $$ = new_and(p, $1, $3);
                    }
                | expr keyword_or expr
                    {
                      $$ = new_or(p, $1, $3);
                    }
                | keyword_not opt_nl expr
                    {
                      $$ = call_uni_op(p, cond($3), "!");
                    }
                | '!' command_call
                    {
                      $$ = call_uni_op(p, cond($2), "!");
                    }
                | arg tASSOC {p->in_kwarg++;} p_expr
                    {
                      /* expr => pattern (raises NoMatchingPatternError on failure) */
                      p->in_kwarg--;
                      $$ = new_match_pat(p, $1, $4, TRUE);
                    }
                | arg keyword_in {p->in_kwarg++;} p_expr
                    {
                      /* expr in pattern (returns true/false) */
                      p->in_kwarg--;
                      $$ = new_match_pat(p, $1, $4, FALSE);
                    }
                | arg   %prec tLOWEST
                ;

defn_head       : keyword_def fname
                    {
                      $$ = new_def(p, $2);
                      p->cmdarg_stack = 0;
                      p->in_def++;
                      nvars_block(p);
                    }
                ;

defs_head       : keyword_def singleton dot_or_colon
                    {
                      p->lstate = EXPR_FNAME;
                    }
                    fname
                    {
                      $$ = new_sdef(p, $2, $5);
                      p->cmdarg_stack = 0;
                      p->in_def++;
                      p->in_single++;
                      nvars_block(p);
                      p->lstate = EXPR_ENDFN; /* force for args */
                    }
                ;

expr_value      : expr
                    {
                      if (!$1) $$ = new_nil(p);
                      else {
                        $$ = $1;
                      }
                    }
                ;

command_call    : command
                | block_command
                ;

block_command   : block_call
                | block_call call_op2 operation2 command_args
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                    }
                ;

cmd_brace_block : tLBRACE_ARG
                    {
                      local_nest(p);
                      nvars_nest(p);
                    }
                  opt_block_param
                  compstmt
                  '}'
                    {
                      $$ = new_block(p, $3, $4);
                      local_unnest(p);
                      nvars_unnest(p);
                    }
                ;

command         : operation command_args       %prec tLOWEST
                    {
                      $$ = new_fcall(p, $1, $2);
                    }
                | operation command_args cmd_brace_block
                    {
                      args_with_block(p, $2, $3);
                      $$ = new_fcall(p, $1, $2);
                    }
                | primary_value call_op operation2 command_args     %prec tLOWEST
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                    }
                | primary_value call_op operation2 command_args cmd_brace_block
                    {
                      args_with_block(p, $4, $5);
                      $$ = new_call(p, $1, $3, $4, $2);
                   }
                | primary_value tCOLON2 operation2 command_args %prec tLOWEST
                    {
                      $$ = new_call(p, $1, $3, $4, tCOLON2);
                    }
                | primary_value tCOLON2 operation2 command_args cmd_brace_block
                    {
                      args_with_block(p, $4, $5);
                      $$ = new_call(p, $1, $3, $4, tCOLON2);
                    }
                | keyword_super command_args
                    {
                      $$ = new_super(p, $2);
                    }
                | keyword_yield command_args
                    {
                      $$ = new_yield(p, $2);
                    }
                | keyword_return call_args
                    {
                      $$ = new_return(p, ret_args(p, $2));
                    }
                | keyword_break call_args
                    {
                      $$ = new_break(p, ret_args(p, $2));
                    }
                | keyword_next call_args
                    {
                      $$ = new_next(p, ret_args(p, $2));
                    }
                ;

mlhs            : mlhs_basic
                    {
                      $$ = $1;
                    }
                | tLPAREN mlhs_inner rparen
                    {
                      $$ = $2;
                    }
                ;

mlhs_inner      : mlhs_basic
                | tLPAREN mlhs_inner rparen
                    {
                      $$ = $2;
                    }
                ;

mlhs_basic      : mlhs_list
                    {
                      $$ = list1($1);
                    }
                | mlhs_list mlhs_item
                    {
                      $$ = list1(push($1,$2));
                    }
                | mlhs_list tSTAR mlhs_node
                    {
                      $$ = list2($1, $3);
                    }
                | mlhs_list tSTAR mlhs_node ',' mlhs_post
                    {
                      $$ = list3($1, $3, $5);
                    }
                | mlhs_list tSTAR
                    {
                      $$ = list2($1, new_nil(p));
                    }
                | mlhs_list tSTAR ',' mlhs_post
                    {
                      $$ = list3($1, new_nil(p), $4);
                    }
                | tSTAR mlhs_node
                    {
                      $$ = list2(0, $2);
                    }
                | tSTAR mlhs_node ',' mlhs_post
                    {
                      $$ = list3(0, $2, $4);
                    }
                | tSTAR
                    {
                      $$ = list2(0, new_nil(p));
                    }
                | tSTAR ',' mlhs_post
                    {
                      $$ = list3(0, new_nil(p), $3);
                    }
                ;

mlhs_item       : mlhs_node
                | tLPAREN mlhs_inner rparen
                    {
                      $$ = new_masgn(p, $2, NULL);
                    }
                ;

mlhs_list       : mlhs_item ','
                    {
                      $$ = list1($1);
                    }
                | mlhs_list mlhs_item ','
                    {
                      $$ = push($1, $2);
                    }
                ;

mlhs_post       : mlhs_item
                    {
                      $$ = list1($1);
                    }
                | mlhs_list mlhs_item
                    {
                      $$ = push($1, $2);
                    }
                ;

mlhs_node       : variable
                    {
                      assignable(p, $1);
                    }
                | primary_value '[' opt_call_args ']'
                    {
                      $$ = new_call(p, $1, intern_op(aref), $3, '.');
                    }
                | primary_value call_op tIDENTIFIER
                    {
                      $$ = new_call(p, $1, $3, 0, $2);
                    }
                | primary_value tCOLON2 tIDENTIFIER
                    {
                      $$ = new_call(p, $1, $3, 0, tCOLON2);
                    }
                | primary_value call_op tCONSTANT
                    {
                      $$ = new_call(p, $1, $3, 0, $2);
                    }
                | primary_value tCOLON2 tCONSTANT
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "dynamic constant assignment");
                      $$ = new_colon2(p, $1, $3);
                    }
                | tCOLON3 tCONSTANT
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "dynamic constant assignment");
                      $$ = new_colon3(p, $2);
                    }
                | backref
                    {
                      backref_error(p, $1);
                      $$ = 0;
                    }
                ;

lhs             : variable
                    {
                      assignable(p, $1);
                    }
                | primary_value '[' opt_call_args ']'
                    {
                      $$ = new_call(p, $1, intern_op(aref), $3, '.');
                    }
                | primary_value call_op tIDENTIFIER
                    {
                      $$ = new_call(p, $1, $3, 0, $2);
                    }
                | primary_value tCOLON2 tIDENTIFIER
                    {
                      $$ = new_call(p, $1, $3, 0, tCOLON2);
                    }
                | primary_value call_op tCONSTANT
                    {
                      $$ = new_call(p, $1, $3, 0, $2);
                    }
                | primary_value tCOLON2 tCONSTANT
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "dynamic constant assignment");
                      $$ = new_colon2(p, $1, $3);
                    }
                | tCOLON3 tCONSTANT
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "dynamic constant assignment");
                      $$ = new_colon3(p, $2);
                    }
                | backref
                    {
                      backref_error(p, $1);
                      $$ = 0;
                    }
                | tNUMPARAM
                    {
                      yyerror(&@1, p, "can't assign to numbered parameter");
                    }
                ;

cname           : tIDENTIFIER
                    {
                      yyerror(&@1, p, "class/module name must be CONSTANT");
                    }
                | tCONSTANT
                ;

cpath           : tCOLON3 cname
                    {
                      $$ = cons(int_to_node(1), sym_to_node($2));
                    }
                | cname
                    {
                      $$ = cons(int_to_node(0), sym_to_node($1));
                    }
                | primary_value tCOLON2 cname
                    {
                      void_expr_error(p, $1);
                      $$ = cons($1, sym_to_node($3));
                    }
                ;

fname           : tIDENTIFIER
                | tCONSTANT
                | tFID
                | op
                    {
                      p->lstate = EXPR_ENDFN;
                      $$ = $1;
                    }
                | reswords
                    {
                      p->lstate = EXPR_ENDFN;
                      $$ = $<id>1;
                    }
                ;

fsym            : fname
                | basic_symbol
                ;

undef_list      : fsym
                    {
                      $$ = cons(sym_to_node($1), 0);
                    }
                | undef_list ',' {p->lstate = EXPR_FNAME;} fsym
                    {
                      $$ = push($1, sym_to_node($4));
                    }
                ;

op              : '|'           { $$ = intern_op(or);     }
                | '^'           { $$ = intern_op(xor);    }
                | '&'           { $$ = intern_op(and);    }
                | tCMP          { $$ = intern_op(cmp);    }
                | tEQ           { $$ = intern_op(eq);     }
                | tEQQ          { $$ = intern_op(eqq);    }
                | tMATCH        { $$ = intern_op(match);  }
                | tNMATCH       { $$ = intern_op(nmatch); }
                | '>'           { $$ = intern_op(gt);     }
                | tGEQ          { $$ = intern_op(ge);     }
                | '<'           { $$ = intern_op(lt);     }
                | tLEQ          { $$ = intern_op(le);     }
                | tNEQ          { $$ = intern_op(neq);    }
                | tLSHFT        { $$ = intern_op(lshift); }
                | tRSHFT        { $$ = intern_op(rshift); }
                | '+'           { $$ = intern_op(add);    }
                | '-'           { $$ = intern_op(sub);    }
                | '*'           { $$ = intern_op(mul);    }
                | tSTAR         { $$ = intern_op(mul);    }
                | '/'           { $$ = intern_op(div);    }
                | '%'           { $$ = intern_op(mod);    }
                | tPOW          { $$ = intern_op(pow);    }
                | tDSTAR        { $$ = intern_op(pow);    }
                | '!'           { $$ = intern_op(not);    }
                | '~'           { $$ = intern_op(neg);    }
                | tUPLUS        { $$ = intern_op(plus);   }
                | tUMINUS       { $$ = intern_op(minus);  }
                | tAREF         { $$ = intern_op(aref);   }
                | tASET         { $$ = intern_op(aset);   }
                | '`'           { $$ = intern_op(tick);   }
                ;

reswords        : keyword__LINE__ | keyword__FILE__ | keyword__ENCODING__
                | keyword_BEGIN | keyword_END
                | keyword_alias | keyword_and | keyword_begin
                | keyword_break | keyword_case | keyword_class | keyword_def
                | keyword_do | keyword_else | keyword_elsif
                | keyword_end | keyword_ensure | keyword_false
                | keyword_for | keyword_in | keyword_module | keyword_next
                | keyword_nil | keyword_not | keyword_or | keyword_redo
                | keyword_rescue | keyword_retry | keyword_return | keyword_self
                | keyword_super | keyword_then | keyword_true | keyword_undef
                | keyword_when | keyword_yield | keyword_if | keyword_unless
                | keyword_while | keyword_until
                ;

arg             : lhs '=' arg_rhs
                    {
                      $$ = new_asgn(p, $1, $3);
                    }
                | var_lhs tOP_ASGN arg_rhs
                    {
                      $$ = new_op_asgn(p, $1, $2, $3);
                    }
                | primary_value '[' opt_call_args ']' tOP_ASGN arg_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, intern_op(aref), $3, '.'), $5, $6);
                    }
                | primary_value call_op tIDENTIFIER tOP_ASGN arg_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, $2), $4, $5);
                    }
                | primary_value call_op tCONSTANT tOP_ASGN arg_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, $2), $4, $5);
                    }
                | primary_value tCOLON2 tIDENTIFIER tOP_ASGN arg_rhs
                    {
                      $$ = new_op_asgn(p, new_call(p, $1, $3, 0, tCOLON2), $4, $5);
                    }
                | primary_value tCOLON2 tCONSTANT tOP_ASGN arg_rhs
                    {
                      yyerror(&@1, p, "constant re-assignment");
                      $$ = new_stmts(p, 0);
                    }
                | tCOLON3 tCONSTANT tOP_ASGN arg_rhs
                    {
                      yyerror(&@1, p, "constant re-assignment");
                      $$ = new_stmts(p, 0);
                    }
                | backref tOP_ASGN arg_rhs
                    {
                      backref_error(p, $1);
                      $$ = new_stmts(p, 0);
                    }
                | arg tDOT2 arg
                    {
                      $$ = new_dot2(p, $1, $3);
                    }
                | arg tDOT2
                    {
                      $$ = new_dot2(p, $1, new_nil(p));
                    }
                | tBDOT2 arg
                    {
                      $$ = new_dot2(p, new_nil(p), $2);
                    }
                | arg tDOT3 arg
                    {
                      $$ = new_dot3(p, $1, $3);
                    }
                | arg tDOT3
                    {
                      $$ = new_dot3(p, $1, new_nil(p));
                    }
                | tBDOT3 arg
                    {
                      $$ = new_dot3(p, new_nil(p), $2);
                    }
                | arg '+' arg
                    {
                      $$ = call_bin_op(p, $1, "+", $3);
                    }
                | arg '-' arg
                    {
                      $$ = call_bin_op(p, $1, "-", $3);
                    }
                | arg '*' arg
                    {
                      $$ = call_bin_op(p, $1, "*", $3);
                    }
                | arg '/' arg
                    {
                      $$ = call_bin_op(p, $1, "/", $3);
                    }
                | arg '%' arg
                    {
                      $$ = call_bin_op(p, $1, "%", $3);
                    }
                | arg tPOW arg
                    {
                      $$ = call_bin_op(p, $1, "**", $3);
                    }
                | tUMINUS_NUM tINTEGER tPOW arg
                    {
                      $$ = new_negate(p, call_bin_op(p, $2, "**", $4));
                    }
                | tUMINUS_NUM tFLOAT tPOW arg
                    {
                      $$ = new_negate(p, call_bin_op(p, $2, "**", $4));
                    }
                | tUPLUS arg
                    {
                      $$ = call_uni_op(p, $2, "+@");
                    }
                | tUMINUS arg
                    {
                      $$ = new_negate(p, $2);
                    }
                | arg '|' arg
                    {
                      $$ = call_bin_op(p, $1, "|", $3);
                    }
                | arg '^' arg
                    {
                      $$ = call_bin_op(p, $1, "^", $3);
                    }
                | arg '&' arg
                    {
                      $$ = call_bin_op(p, $1, "&", $3);
                    }
                | arg tCMP arg
                    {
                      $$ = call_bin_op(p, $1, "<=>", $3);
                    }
                | arg '>' arg
                    {
                      $$ = call_bin_op(p, $1, ">", $3);
                    }
                | arg tGEQ arg
                    {
                      $$ = call_bin_op(p, $1, ">=", $3);
                    }
                | arg '<' arg
                    {
                      $$ = call_bin_op(p, $1, "<", $3);
                    }
                | arg tLEQ arg
                    {
                      $$ = call_bin_op(p, $1, "<=", $3);
                    }
                | arg tEQ arg
                    {
                      $$ = call_bin_op(p, $1, "==", $3);
                    }
                | arg tEQQ arg
                    {
                      $$ = call_bin_op(p, $1, "===", $3);
                    }
                | arg tNEQ arg
                    {
                      $$ = call_bin_op(p, $1, "!=", $3);
                    }
                | arg tMATCH arg
                    {
                      $$ = call_bin_op(p, $1, "=~", $3);
                    }
                | arg tNMATCH arg
                    {
                      $$ = call_bin_op(p, $1, "!~", $3);
                    }
                | '!' arg
                    {
                      $$ = call_uni_op(p, cond($2), "!");
                    }
                | '~' arg
                    {
                      $$ = call_uni_op(p, cond($2), "~");
                    }
                | arg tLSHFT arg
                    {
                      $$ = call_bin_op(p, $1, "<<", $3);
                    }
                | arg tRSHFT arg
                    {
                      $$ = call_bin_op(p, $1, ">>", $3);
                    }
                | arg tANDOP arg
                    {
                      $$ = new_and(p, $1, $3);
                    }
                | arg tOROP arg
                    {
                      $$ = new_or(p, $1, $3);
                    }
                | arg '?' arg opt_nl ':' arg
                    {
                      $$ = new_if(p, cond($1), $3, $6);
                    }
                | arg '?' arg opt_nl tLABEL_TAG arg
                    {
                      $$ = new_if(p, cond($1), $3, $6);
                    }
                | defn_head f_opt_arglist_paren '=' arg
                    {
                      $$ = $1;
                      endless_method_name(p, $1);
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, $4);
                      nvars_unnest(p);
                      p->in_def--;
                    }
                | defn_head f_opt_arglist_paren '=' arg modifier_rescue arg
                    {
                      $$ = $1;
                      endless_method_name(p, $1);
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, new_mod_rescue(p, $4, $6));
                      nvars_unnest(p);
                      p->in_def--;
                    }
                | defs_head f_opt_arglist_paren '=' arg
                    {
                      $$ = $1;
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, $4);
                      nvars_unnest(p);
                      p->in_def--;
                      p->in_single--;
                    }
                | defs_head f_opt_arglist_paren '=' arg modifier_rescue arg
                    {
                      $$ = $1;
                      void_expr_error(p, $4);
                      defn_setup(p, $$, $2, new_mod_rescue(p, $4, $6));
                      nvars_unnest(p);
                      p->in_def--;
                      p->in_single--;
                    }
                | primary
                    {
                      $$ = $1;
                    }
                ;

aref_args       : none
                | args trailer
                    {
                      $$ = $1;
                    }
                | args comma assocs trailer
                    {
                      $$ = push($1, new_hash(p, $3));
                    }
                | assocs trailer
                    {
                      $$ = cons(new_hash(p, $1), 0);
                    }
                ;

arg_rhs         : arg %prec tOP_ASGN
                    {
                      $$ = $1;
                    }
                | arg modifier_rescue arg
                    {
                      void_expr_error(p, $1);
                      $$ = new_mod_rescue(p, $1, $3);
                    }
                ;

paren_args      : '(' opt_call_args ')'
                    {
                      $$ = $2;
                    }
                | '(' args comma tBDOT3 rparen
                    {
                      mrb_sym r = intern_op(mul);
                      mrb_sym k = intern_op(pow);
                      mrb_sym b = intern_op(and);
                      $$ = new_callargs(p, push($2, new_splat(p, new_lvar(p, r))),
                                        list1(cons(new_kw_rest_args(p, 0), new_lvar(p, k))),
                                        new_block_arg(p, new_lvar(p, b)));
                    }
                | '(' tBDOT3 rparen
                    {
                      mrb_sym r = intern_op(mul);
                      mrb_sym k = intern_op(pow);
                      mrb_sym b = intern_op(and);
                      if (local_var_p(p, r) && local_var_p(p, k) && local_var_p(p, b)) {
                        $$ = new_callargs(p, list1(new_splat(p, new_lvar(p, r))),
                                          list1(cons(new_kw_rest_args(p, 0), new_lvar(p, k))),
                                          new_block_arg(p, new_lvar(p, b)));
                      }
                      else {
                        yyerror(&@1, p, "unexpected argument forwarding ...");
                        $$ = 0;
                      }
                    }
                ;

opt_paren_args  : none
                | paren_args
                ;

opt_call_args   : none
                | call_args opt_terms
                | args comma
                    {
                      $$ = new_callargs(p,$1,0,0);
                    }
                | args comma assocs comma
                    {
                      $$ = new_callargs(p,$1,$3,0);
                    }
                | assocs comma
                    {
                      $$ = new_callargs(p,0,$1,0);
                    }
                ;

call_args       : command
                    {
                      void_expr_error(p, $1);
                      $$ = new_callargs(p, list1($1), 0, 0);
                    }
                | args opt_block_arg
                    {
                      $$ = new_callargs(p, $1, 0, $2);
                    }
                | assocs opt_block_arg
                    {
                      $$ = new_callargs(p, 0, $1, $2);
                    }
                | args comma assocs opt_block_arg
                    {
                      $$ = new_callargs(p, $1, $3, $4);
                    }
                | block_arg
                    {
                      $$ = new_callargs(p, 0, 0, $1);
                    }
                ;

command_args    :  {
                      $<stack>$ = p->cmdarg_stack;
                      CMDARG_PUSH(1);
                    }
                  call_args
                    {
                      p->cmdarg_stack = $<stack>1;
                      $$ = $2;
                    }
                ;

block_arg       : tAMPER arg
                    {
                      $$ = new_block_arg(p, $2);
                    }
                | tAMPER
                    {
                      $$ = new_block_arg(p, 0);
                    }
                ;

opt_block_arg   : comma block_arg
                    {
                      $$ = $2;
                    }
                | none
                    {
                      $$ = 0;
                    }
                ;

comma           : ','  opt_nl
                ;

args            : arg
                    {
                      void_expr_error(p, $1);
                      $$ = list1($1);
                    }
                | tSTAR
                    {
                      $$ = list1(new_splat(p, new_lvar(p, intern_op(mul))));
                    }
                | tSTAR arg
                    {
                      $$ = list1(new_splat(p, $2));
                    }
                | args comma arg
                    {
                      void_expr_error(p, $3);
                      $$ = push($1, $3);
                    }
                | args comma tSTAR
                    {
                      $$ = push($1, new_splat(p, new_lvar(p, intern_op(mul))));
                    }
                | args comma tSTAR arg
                    {
                      $$ = push($1, new_splat(p, $4));
                    }
                ;

mrhs            : args comma arg
                    {
                      void_expr_error(p, $3);
                      $$ = push($1, $3);
                    }
                | args comma tSTAR arg
                    {
                      $$ = push($1, new_splat(p, $4));
                    }
                | tSTAR arg
                    {
                      $$ = list1(new_splat(p, $2));
                    }
                ;

primary         : literal
                | string
                    {
                      $$ = new_str(p, $1);
                    }
                | xstring
                    {
                      $$ = new_xstr(p, $1);
                    }
                | regexp
                | heredoc
                | var_ref
                | backref
                | tFID
                    {
                      $$ = new_fcall(p, $1, 0);
                    }
                | keyword_begin
                    {
                      $<stack>$ = p->cmdarg_stack;
                      p->cmdarg_stack = 0;
                    }
                  bodystmt
                  keyword_end
                    {
                      p->cmdarg_stack = $<stack>2;
                      $$ = new_begin(p, $3);
                    }
                | tLPAREN_ARG
                    {
                      $<stack>$ = p->cmdarg_stack;
                      p->cmdarg_stack = 0;
                    }
                  compstmt {p->lstate = EXPR_ENDARG;} rparen
                    {
                      p->cmdarg_stack = $<stack>2;
                      $$ = $3;
                    }
                | tLPAREN_ARG {p->lstate = EXPR_ENDARG;} rparen
                    {
                      $$ = new_nil(p);
                    }
                | tLPAREN compstmt ')'
                    {
                      $$ = $2;
                    }
                | primary_value tCOLON2 tCONSTANT
                    {
                      $$ = new_colon2(p, $1, $3);
                    }
                | tCOLON3 tCONSTANT
                    {
                      $$ = new_colon3(p, $2);
                    }
                | tLBRACK aref_args ']'
                    {
                      $$ = new_array(p, $2);
                    }
                | tLBRACE assoc_list '}'
                    {
                      $$ = new_hash(p, $2);
                    }
                | keyword_return
                    {
                      $$ = new_return(p, 0);
                    }
                | keyword_yield opt_paren_args
                    {
                      $$ = new_yield(p, $2);
                    }
                | keyword_not '(' expr rparen
                    {
                      $$ = call_uni_op(p, cond($3), "!");
                    }
                | keyword_not '(' rparen
                    {
                      $$ = call_uni_op(p, new_nil(p), "!");
                    }
                | operation brace_block
                    {
                      $$ = new_fcall(p, $1, new_callargs(p, 0, 0, $2));
                    }
                | method_call
                | method_call brace_block
                    {
                      call_with_block(p, $1, $2);
                      $$ = $1;
                    }
                | tLAMBDA
                    {
                      local_nest(p);
                      nvars_nest(p);
                      $<num>$ = p->lpar_beg;
                      p->lpar_beg = ++p->paren_nest;
                    }
                  f_larglist
                    {
                      $<stack>$ = p->cmdarg_stack;
                      p->cmdarg_stack = 0;
                    }
                  lambda_body
                    {
                      p->lpar_beg = $<num>2;
                      $$ = new_lambda(p, $3, $5);
                      local_unnest(p);
                      nvars_unnest(p);
                      p->cmdarg_stack = $<stack>4;
                      CMDARG_LEXPOP();
                    }
                | keyword_if expr_value then
                  compstmt
                  if_tail
                  keyword_end
                    {
                      $$ = new_if(p, cond($2), $4, $5);
                      SET_LINENO($$, $1);
                    }
                | keyword_unless expr_value then
                  compstmt
                  opt_else
                  keyword_end
                    {
                      $$ = new_if(p, cond($2), $5, $4);
                      SET_LINENO($$, $1);
                    }
                | keyword_while {COND_PUSH(1);} expr_value do {COND_POP();}
                  compstmt
                  keyword_end
                    {
                      $$ = new_while(p, cond($3), $6);
                      SET_LINENO($$, $1);
                    }
                | keyword_until {COND_PUSH(1);} expr_value do {COND_POP();}
                  compstmt
                  keyword_end
                    {
                      $$ = new_until(p, cond($3), $6);
                      SET_LINENO($$, $1);
                    }
                | keyword_case expr_value opt_terms
                  case_body
                  keyword_end
                    {
                      $$ = new_case(p, $2, $4);
                    }
                | keyword_case opt_terms case_body keyword_end
                    {
                      $$ = new_case(p, 0, $3);
                    }
                | keyword_case expr_value opt_terms
                  keyword_in p_expr then
                  compstmt
                  in_clauses
                  keyword_end
                    {
                      node *in_clause = new_in(p, $5, NULL, $7, FALSE);
                      $$ = new_case_match(p, $2, cons(in_clause, $8));
                    }
                | keyword_case expr_value opt_terms
                  keyword_in p_expr modifier_if expr_value then
                  compstmt
                  in_clauses
                  keyword_end
                    {
                      node *in_clause = new_in(p, $5, $7, $9, FALSE);
                      $$ = new_case_match(p, $2, cons(in_clause, $10));
                    }
                | keyword_case expr_value opt_terms
                  keyword_in p_expr modifier_unless expr_value then
                  compstmt
                  in_clauses
                  keyword_end
                    {
                      node *in_clause = new_in(p, $5, $7, $9, TRUE);
                      $$ = new_case_match(p, $2, cons(in_clause, $10));
                    }
                | keyword_for for_var keyword_in
                  {COND_PUSH(1);}
                  expr_value do
                  {COND_POP();}
                  compstmt
                  keyword_end
                    {
                      $$ = new_for(p, $2, $5, $8);
                      SET_LINENO($$, $1);
                    }
                | keyword_class
                  cpath superclass
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "class definition in method body");
                      $<nd>$ = local_switch(p);
                      nvars_block(p);
                    }
                  bodystmt
                  keyword_end
                    {
                      $$ = new_class(p, $2, $3, $5);
                      SET_LINENO($$, $1);
                      local_resume(p, $<nd>4);
                      nvars_unnest(p);
                    }
                | keyword_class
                  tLSHFT expr
                    {
                      $<num>$ = p->in_def;
                      p->in_def = 0;
                    }
                  term
                    {
                      $<nd>$ = cons(local_switch(p), int_to_node(p->in_single));
                      nvars_block(p);
                      p->in_single = 0;
                    }
                  bodystmt
                  keyword_end
                    {
                      $$ = new_sclass(p, $3, $7);
                      SET_LINENO($$, $1);
                      local_resume(p, $<nd>6->car);
                      nvars_unnest(p);
                      p->in_def = $<num>4;
                      p->in_single = node_to_int($<nd>6->cdr);
                    }
                | keyword_module
                  cpath
                    {
                      if (p->in_def || p->in_single)
                        yyerror(&@1, p, "module definition in method body");
                      $<nd>$ = local_switch(p);
                      nvars_block(p);
                    }
                  bodystmt
                  keyword_end
                    {
                      $$ = new_module(p, $2, $4);
                      SET_LINENO($$, $1);
                      local_resume(p, $<nd>3);
                      nvars_unnest(p);
                    }
                | defn_head
                  f_arglist
                  bodystmt
                  keyword_end
                    {
                      $$ = $1;
                      defn_setup(p, $$, $2, $3);
                      nvars_unnest(p);
                      p->in_def--;
                    }
                | defs_head
                  f_arglist
                  bodystmt
                  keyword_end
                    {
                      $$ = $1;
                      defn_setup(p, $$, $2, $3);
                      nvars_unnest(p);
                      p->in_def--;
                      p->in_single--;
                    }
                | keyword_break
                    {
                      $$ = new_break(p, 0);
                    }
                | keyword_next
                    {
                      $$ = new_next(p, 0);
                    }
                | keyword_redo
                    {
                      $$ = new_redo(p);
                    }
                | keyword_retry
                    {
                      $$ = new_retry(p);
                    }
                ;

primary_value   : primary
                    {
                      $$ = $1;
                      if (!$$) $$ = new_nil(p);
                    }
                ;

then            : term
                | keyword_then
                | term keyword_then
                ;

do              : term
                | keyword_do_cond
                ;

if_tail         : opt_else
                | keyword_elsif expr_value then
                  compstmt
                  if_tail
                    {
                      $$ = new_if(p, cond($2), $4, $5);
                    }
                ;

opt_else        : none
                | keyword_else compstmt
                    {
                      $$ = $2;
                    }
                ;

for_var         : lhs
                    {
                      $$ = list1(list1($1));
                    }
                | mlhs
                ;

f_margs         : f_arg
                    {
                      $$ = list3($1,0,0);
                    }
                | f_arg ',' tSTAR f_norm_arg
                    {
                      $$ = list3($1, new_lvar(p, $4), 0);
                    }
                | f_arg ',' tSTAR f_norm_arg ',' f_arg
                    {
                      $$ = list3($1, new_lvar(p, $4), $6);
                    }
                | f_arg ',' tSTAR
                    {
                      local_add_f(p, intern_op(mul));
                      $$ = list3($1, int_to_node(-1), 0);
                    }
                | f_arg ',' tSTAR ',' f_arg
                    {
                      $$ = list3($1, int_to_node(-1), $5);
                    }
                | tSTAR f_norm_arg
                    {
                      $$ = list3(0, new_lvar(p, $2), 0);
                    }
                | tSTAR f_norm_arg ',' f_arg
                    {
                      $$ = list3(0, new_lvar(p, $2), $4);
                    }
                | tSTAR
                    {
                      local_add_f(p, intern_op(mul));
                      $$ = list3(0, int_to_node(-1), 0);
                    }
                | tSTAR ','
                    {
                      local_add_f(p, intern_op(mul));
                    }
                  f_arg
                    {
                      $$ = list3(0, int_to_node(-1), $4);
                    }
                ;

block_args_tail : f_block_kwarg ',' f_kwrest opt_f_block_arg
                    {
                      $$ = new_args_tail(p, $1, $3, $4);
                    }
                | f_block_kwarg opt_f_block_arg
                    {
                      $$ = new_args_tail(p, $1, 0, $2);
                    }
                | f_kwrest opt_f_block_arg
                    {
                      $$ = new_args_tail(p, 0, $1, $2);
                    }
                | f_block_arg
                    {
                      $$ = new_args_tail(p, 0, 0, $1);
                    }
                ;

opt_block_args_tail : ',' block_args_tail
                    {
                      $$ = $2;
                    }
                | /* none */
                    {
                      $$ = new_args_tail(p, 0, 0, 0);
                    }
                ;

block_param     : f_arg ',' f_block_optarg ',' f_rest_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, $3, $5, 0, $6);
                    }
                | f_arg ',' f_block_optarg ',' f_rest_arg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, $3, $5, $7, $8);
                    }
                | f_arg ',' f_block_optarg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, $3, 0, 0, $4);
                    }
                | f_arg ',' f_block_optarg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, $3, 0, $5, $6);
                    }
                | f_arg ',' f_rest_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, 0, $3, 0, $4);
                    }
                | f_arg ',' opt_block_args_tail
                    {
                      $$ = new_args(p, $1, 0, 0, 0, $3);
                    }
                | f_arg ',' f_rest_arg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, 0, $3, $5, $6);
                    }
                | f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, $1, 0, 0, 0, $2);
                    }
                | f_block_optarg ',' f_rest_arg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, $1, $3, 0, $4);
                    }
                | f_block_optarg ',' f_rest_arg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, $1, $3, $5, $6);
                    }
                | f_block_optarg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, $1, 0, 0, $2);
                    }
                | f_block_optarg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, $1, 0, $3, $4);
                    }
                | f_rest_arg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, 0, $1, 0, $2);
                    }
                | f_rest_arg ',' f_arg opt_block_args_tail
                    {
                      $$ = new_args(p, 0, 0, $1, $3, $4);
                    }
                | block_args_tail
                    {
                      $$ = new_args(p, 0, 0, 0, 0, $1);
                    }
                ;

opt_block_param : none
                    {
                      local_add_blk(p);
                      $$ = 0;
                    }
                | block_param_def
                   {
                      p->cmd_start = TRUE;
                      $$ = $1;
                    }
                ;

block_param_def : '|' {local_add_blk(p);} opt_bv_decl '|'
                    {
                      $$ = 0;
                    }
                | tOROP
                    {
                      local_add_blk(p);
                      $$ = 0;
                    }
                | '|' block_param opt_bv_decl '|'
                    {
                      $$ = $2;
                    }
                ;

opt_bv_decl     : opt_nl
                    {
                      $$ = 0;
                    }
                | opt_nl ';' bv_decls opt_nl
                    {
                      $$ = 0;
                    }
                ;

bv_decls        : bvar
                | bv_decls ',' bvar
                ;

bvar            : tIDENTIFIER
                    {
                      local_add_f(p, $1);
                      new_bv(p, $1);
                    }
                | f_bad_arg
                ;

f_larglist      : '(' f_args opt_bv_decl ')'
                    {
                      $$ = $2;
                    }
                | f_args
                    {
                      $$ = $1;
                    }
                ;

lambda_body     : tLAMBEG compstmt '}'
                    {
                      $$ = $2;
                    }
                | keyword_do_LAMBDA bodystmt keyword_end
                    {
                      $$ = $2;
                    }
                ;

do_block        : keyword_do_block
                    {
                      local_nest(p);
                      nvars_nest(p);
                      $<num>$ = p->lineno;
                    }
                  opt_block_param
                  bodystmt
                  keyword_end
                    {
                      $$ = new_block(p,$3,$4);
                      SET_LINENO($$, $<num>2);
                      local_unnest(p);
                      nvars_unnest(p);
                    }
                ;

block_call      : command do_block
                    {
                      call_with_block(p, $1, $2);
                      $$ = $1;
                    }
                | block_call call_op2 operation2 opt_paren_args
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                    }
                | block_call call_op2 operation2 opt_paren_args brace_block
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                      call_with_block(p, $$, $5);
                    }
                | block_call call_op2 operation2 command_args do_block
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                      call_with_block(p, $$, $5);
                    }
                ;

method_call     : operation paren_args
                    {
                      $$ = new_fcall(p, $1, $2);
                    }
                | primary_value call_op operation2 opt_paren_args
                    {
                      $$ = new_call(p, $1, $3, $4, $2);
                    }
                | primary_value tCOLON2 operation2 paren_args
                    {
                      $$ = new_call(p, $1, $3, $4, tCOLON2);
                    }
                | primary_value tCOLON2 operation3
                    {
                      $$ = new_call(p, $1, $3, 0, tCOLON2);
                    }
                | primary_value call_op paren_args
                    {
                      $$ = new_call(p, $1, MRB_SYM(call), $3, $2);
                    }
                | primary_value tCOLON2 paren_args
                    {
                      $$ = new_call(p, $1, MRB_SYM(call), $3, tCOLON2);
                    }
                | keyword_super paren_args
                    {
                      $$ = new_super(p, $2);
                    }
                | keyword_super
                    {
                      $$ = new_zsuper(p);
                    }
                | primary_value '[' opt_call_args ']'
                    {
                      $$ = new_call(p, $1, intern_op(aref), $3, '.');
                    }
                ;

brace_block     : '{'
                    {
                      local_nest(p);
                      nvars_nest(p);
                      $<num>$ = p->lineno;
                    }
                  opt_block_param
                  compstmt '}'
                    {
                      $$ = new_block(p,$3,$4);
                      SET_LINENO($$, $<num>2);
                      local_unnest(p);
                      nvars_unnest(p);
                    }
                | keyword_do
                    {
                      local_nest(p);
                      nvars_nest(p);
                      $<num>$ = p->lineno;
                    }
                  opt_block_param
                  bodystmt keyword_end
                    {
                      $$ = new_block(p,$3,$4);
                      SET_LINENO($$, $<num>2);
                      local_unnest(p);
                      nvars_unnest(p);
                    }
                ;

case_body       : keyword_when args then
                  compstmt
                  cases
                    {
                      $$ = cons(cons($2, $4), $5);
                    }
                ;

cases           : opt_else
                    {
                      if ($1) {
                        $$ = cons(cons(0, $1), 0);
                      }
                      else {
                        $$ = 0;
                      }
                    }
                | case_body
                ;

/* Pattern matching in-clauses for case/in */
/* in_kwarg is set by lexer when keyword_in is returned */
in_clauses      : opt_else
                    {
                      $$ = $1 ? list1(new_in(p, NULL, NULL, $1, FALSE)) : 0;
                    }
                | keyword_in p_expr {p->in_kwarg--;} then compstmt in_clauses
                    {
                      node *in_clause = new_in(p, $2, NULL, $5, FALSE);
                      $$ = cons(in_clause, $6);
                    }
                | keyword_in p_expr {p->in_kwarg--;} modifier_if expr_value then compstmt in_clauses
                    {
                      node *in_clause = new_in(p, $2, $5, $7, FALSE);
                      $$ = cons(in_clause, $8);
                    }
                | keyword_in p_expr {p->in_kwarg--;} modifier_unless expr_value then compstmt in_clauses
                    {
                      node *in_clause = new_in(p, $2, $5, $7, TRUE);
                      $$ = cons(in_clause, $8);
                    }
                ;

/* Pattern expressions for case/in */
/* Bracket-less array patterns: in 1, 2, x is same as in [1, 2, x] */
/* Brace-less hash patterns: in a:, b: x is same as in {a:, b: x} */
p_expr          : p_as
                | p_args_head p_as
                    {
                      $$ = new_pat_array(p, push($1, $2), 0, 0);
                    }
                | p_args_head p_rest
                    {
                      $$ = new_pat_array(p, $1, $2, 0);
                    }
                | p_args_head p_rest ',' p_args_post
                    {
                      $$ = new_pat_array(p, $1, $2, $4);
                    }
                | p_rest
                    {
                      $$ = new_pat_array(p, 0, $1, 0);
                    }
                | p_rest ',' p_args_post
                    {
                      $$ = new_pat_array(p, 0, $1, $3);
                    }
                | p_hash_elems
                    {
                      /* Brace-less hash pattern: in a:, b: x */
                      $$ = new_pat_hash(p, $1, 0);
                    }
                | p_hash_elems ',' p_kwrest
                    {
                      /* Brace-less hash pattern with kwrest: in a:, **rest */
                      $$ = new_pat_hash(p, $1, $3);
                    }
                | p_kwrest
                    {
                      /* Brace-less kwrest only: in **rest */
                      $$ = new_pat_hash(p, 0, $1);
                    }
                ;

/* Comma-separated pattern list (prefix) */
p_args_head     : p_as ','
                    {
                      $$ = list1($1);
                    }
                | p_args_head p_as ','
                    {
                      $$ = push($1, $2);
                    }
                ;

/* Comma-separated pattern list (suffix, no trailing comma) */
p_args_post     : p_as
                    {
                      $$ = list1($1);
                    }
                | p_args_post ',' p_as
                    {
                      $$ = push($1, $3);
                    }
                ;

p_as            : p_alt
                | p_alt tASSOC tIDENTIFIER
                    {
                      $$ = new_pat_as(p, $1, $3);
                    }
                ;

p_alt           : p_value
                | p_alt '|' p_value
                    {
                      $$ = new_pat_alt(p, $1, $3);
                    }
                ;

p_value         : p_var
                | numeric
                    {
                      $$ = new_pat_value(p, $1);
                    }
                | symbol
                    {
                      $$ = new_pat_value(p, $1);
                    }
                | string
                    {
                      $$ = new_pat_value(p, new_str(p, $1));
                    }
                | keyword_nil
                    {
                      $$ = new_pat_value(p, new_nil(p));
                    }
                | keyword_true
                    {
                      $$ = new_pat_value(p, new_true(p));
                    }
                | keyword_false
                    {
                      $$ = new_pat_value(p, new_false(p));
                    }
                | p_const
                    {
                      $$ = new_pat_value(p, $1);
                    }
                | p_array
                | p_hash
                | '^' tIDENTIFIER
                    {
                      $$ = new_pat_pin(p, $2);
                    }
                ;

/* Array pattern: [a, b, *rest, c] */
p_array         : tLBRACK p_array_body ']'
                    {
                      $$ = $2;
                    }
                | tLBRACK ']'
                    {
                      $$ = new_pat_array(p, 0, 0, 0);
                    }
                ;

/* Array pattern body - pre elements, optional rest, post elements */
p_array_body    : p_array_elems
                    {
                      /* Just pre elements, no rest */
                      $$ = new_pat_array(p, $1, 0, 0);
                    }
                | p_array_elems ',' p_rest
                    {
                      /* Pre elements + rest, no post */
                      $$ = new_pat_array(p, $1, $3, 0);
                    }
                | p_array_elems ',' p_rest ',' p_array_elems
                    {
                      /* Pre + rest + post */
                      $$ = new_pat_array(p, $1, $3, $5);
                    }
                | p_rest
                    {
                      /* Just rest, no pre or post */
                      $$ = new_pat_array(p, 0, $1, 0);
                    }
                | p_rest ',' p_array_elems
                    {
                      /* Rest + post, no pre */
                      $$ = new_pat_array(p, 0, $1, $3);
                    }
                | p_rest ',' p_array_elems ',' p_rest
                    {
                      /* Find pattern: [*pre, elems, *post] */
                      $$ = new_pat_find(p, $1, $3, $5);
                    }
                ;

/* Non-rest array pattern elements - use p_as, not p_expr to avoid bracket-less recursion */
p_array_elems   : p_as
                    {
                      $$ = list1($1);
                    }
                | p_array_elems ',' p_as
                    {
                      $$ = push($1, $3);
                    }
                ;

/* Rest pattern in array: *var, *_, or just * */
p_rest          : tSTAR tIDENTIFIER
                    {
                      $$ = new_pat_var(p, $2);
                    }
                | tSTAR
                    {
                      /* Anonymous rest pattern */
                      $$ = (node*)-1;
                    }
                ;

/* Constant path for pattern matching: Foo, Foo::Bar, ::Foo */
p_const         : tCONSTANT
                    {
                      $$ = new_const(p, $1);
                    }
                | p_const tCOLON2 tCONSTANT
                    {
                      $$ = new_colon2(p, $1, $3);
                    }
                | tCOLON3 tCONSTANT
                    {
                      $$ = new_colon3(p, $2);
                    }
                ;

/* Hash pattern: {a:, b: x, **rest} */
p_hash          : tLBRACE p_hash_body '}'
                    {
                      $$ = $2;
                    }
                | tLBRACE '}'
                    {
                      $$ = new_pat_hash(p, 0, 0);
                    }
                ;

/* Hash pattern body - pairs and optional kwrest */
p_hash_body     : p_hash_elems
                    {
                      $$ = new_pat_hash(p, $1, 0);
                    }
                | p_hash_elems ',' p_kwrest
                    {
                      $$ = new_pat_hash(p, $1, $3);
                    }
                | p_kwrest
                    {
                      $$ = new_pat_hash(p, 0, $1);
                    }
                ;

/* Hash pattern element list */
p_hash_elems    : p_hash_elem
                    {
                      $$ = list1($1);
                    }
                | p_hash_elems ',' p_hash_elem
                    {
                      $$ = push($1, $3);
                    }
                ;

/* Hash pattern element: key: pattern or key: (shorthand) */
/* Use p_as, not p_expr to avoid brace-less recursion inside hash patterns */
/* Note: CRuby only supports label syntax (foo:), not hashrocket (:foo =>) */
p_hash_elem     : tIDENTIFIER tLABEL_TAG p_as
                    {
                      /* {key: pattern} */
                      $$ = cons(new_sym(p, $1), $3);
                    }
                | tIDENTIFIER tLABEL_TAG
                    {
                      /* {key:} shorthand - binds to variable with same name */
                      $$ = cons(new_sym(p, $1), new_pat_var(p, $1));
                    }
                ;

/* Keyword rest pattern: **var, **nil, or ** */
p_kwrest        : tDSTAR tIDENTIFIER
                    {
                      $$ = new_pat_var(p, $2);
                    }
                | tDSTAR keyword_nil
                    {
                      /* **nil - exact match, no extra keys allowed */
                      $$ = (node*)-1;
                    }
                | tDSTAR
                    {
                      /* ** - anonymous rest, discards extra keys */
                      $$ = (node*)-2;
                    }
                ;

p_var           : tIDENTIFIER
                    {
                      $$ = new_pat_var(p, $1);
                    }
                ;

opt_rescue      : keyword_rescue exc_list exc_var then
                  compstmt
                  opt_rescue
                    {
                      $$ = list1(list3($2, $3, $5));
                      if ($6) $$ = append($$, $6);
                    }
                | none
                ;

exc_list        : arg
                    {
                        $$ = list1($1);
                    }
                | mrhs
                | none
                ;

exc_var         : tASSOC lhs
                    {
                      $$ = $2;
                    }
                | none
                ;

opt_ensure      : keyword_ensure compstmt
                    {
                      $$ = $2;
                    }
                | none
                ;

literal         : numeric
                | symbol
                | words
                | symbols
                ;

string          : string_fragment
                | string string_fragment
                    {
                      $$ = append($1, $2);
                    }
                ;

string_fragment : tCHAR
                    {
                      /* tCHAR is (len . str), wrap as cons list */
                      $$ = list1($1);
                    }
                | tSTRING
                    {
                      /* tSTRING is (len . str), wrap as cons list */
                      $$ = list1($1);
                    }
                | tSTRING_BEG tSTRING
                    {
                      /* $2 is (len . str), wrap as cons list */
                      $$ = list1($2);
                    }
                | tSTRING_BEG string_rep tSTRING
                    {
                      $$ = push($2, $3);
                    }
                ;

string_rep      : string_interp
                | string_rep string_interp
                    {
                      $$ = append($1, $2);
                    }
                ;

string_interp   : tSTRING_MID
                    {
                      /* $1 is already in (len . str) format */
                      $$ = list1($1);
                    }
                | tSTRING_PART
                    {
                      $<nd>$ = push_strterm(p);
                    }
                  compstmt
                  '}'
                    {
                      pop_strterm(p,$<nd>2);
                      /* $1 is already in (len . str) format, create (-1 . node) for expression */
                      node *expr_elem = cons(int_to_node(-1), $3);
                      $$ = list2($1, expr_elem);
                    }
                | tLITERAL_DELIM
                    {
                      $$ = list1(new_literal_delim(p));
                    }
                | tHD_LITERAL_DELIM heredoc_bodies
                    {
                      $$ = list1(new_literal_delim(p));
                    }
                ;

xstring         : tXSTRING_BEG tXSTRING
                    {
                        $$ = cons($2, (node*)NULL);
                    }
                | tXSTRING_BEG string_rep tXSTRING
                    {
                      $$ = push($2, $3);
                    }
                ;

regexp          : tREGEXP_BEG tREGEXP
                    {
                      node *data = $2;  /* ((len . pattern) . (flags . encoding)) */
                      const char *flags = (const char*)data->cdr->car;
                      const char *encoding = (const char*)data->cdr->cdr;
                      /* Use data->car directly as pattern_list: (len . pattern) */
                      node *pattern_list = cons(data->car, (node*)NULL);
                      $$ = new_regx(p, pattern_list, flags, encoding);
                    }
                | tREGEXP_BEG string_rep tREGEXP
                    {
                      node *data = $3;  /* ((len . pattern) . (flags . encoding)) */
                      const char *flags = (const char*)data->cdr->car;
                      const char *encoding = (const char*)data->cdr->cdr;
                      /* Append the pattern from $3->car to the string list $2 */
                      node *complete_list = push($2, data->car);
                      $$ = new_regx(p, complete_list, flags, encoding);
                    }
                ;

heredoc         : tHEREDOC_BEG
                ;

heredoc_bodies  : heredoc_body
                | heredoc_bodies heredoc_body
                ;

heredoc_body    : tHEREDOC_END
                    {
                      parser_heredoc_info *info = parsing_heredoc_info(p);
                      info->doc = push(info->doc, new_str_empty(p));
                      heredoc_end(p);
                    }
                | heredoc_string_rep tHEREDOC_END
                    {
                      heredoc_end(p);
                    }
                ;

heredoc_string_rep : heredoc_string_interp
                   | heredoc_string_rep heredoc_string_interp
                   ;

heredoc_string_interp : tHD_STRING_MID
                    {
                      parser_heredoc_info *info = parsing_heredoc_info(p);
                      info->doc = push(info->doc, $1);
                      heredoc_treat_nextline(p);
                    }
                | tHD_STRING_PART
                    {
                      $<nd>$ = push_strterm(p);
                    }
                  compstmt
                  '}'
                    {
                      pop_strterm(p, $<nd>2);
                      parser_heredoc_info *info = parsing_heredoc_info(p);
                      /* $1 is already in (len . str) format, create (-1 . node) for expression */
                      node *expr_elem = cons(int_to_node(-1), $3);
                      info->doc = push(push(info->doc, $1), expr_elem);
                    }
                ;

words           : tWORDS_BEG tSTRING
                    {
                      $$ = new_words(p, list1($2));
                    }
                | tWORDS_BEG string_rep tSTRING
                    {
                      node *n = $2;
                      n = push(n, $3);
                      $$ = new_words(p, n);
                    }
                ;

symbol          : basic_symbol
                    {
                      $$ = new_sym(p, $1);
                    }
                | tSYMBEG tSTRING_BEG string_rep tSTRING
                    {
                      node *n = $3;
                      p->lstate = EXPR_ENDARG;
                      if (node_to_int($4->car) > 0) {
                        n = push(n, $4);
                      }
                      else {
                        cons_free($4);
                      }
                      $$ = new_dsym(p, n);
                    }
                | tSYMBEG tNUMPARAM
                    {
                      mrb_sym sym = intern_numparam($2);
                      $$ = new_sym(p, sym);
                    }
                ;

basic_symbol    : tSYMBEG sym
                    {
                      p->lstate = EXPR_END;
                      $$ = $2;
                    }
                ;

sym             : fname
                | tIVAR
                | tGVAR
                | tCVAR
                | tSTRING
                    {
                      $$ = new_strsym(p, $1);
                    }
                | tSTRING_BEG tSTRING
                    {
                      $$ = new_strsym(p, $2);
                    }
                ;

symbols         : tSYMBOLS_BEG tSTRING
                    {
                      $$ = new_symbols(p, list1($2));
                    }
                | tSYMBOLS_BEG string_rep tSTRING
                    {
                      node *n = $2;
                      n = push(n, $3);
                      $$ = new_symbols(p, n);
                    }
                ;

numeric         : tINTEGER
                | tFLOAT
                | tUMINUS_NUM tINTEGER          %prec tLOWEST
                    {
                      $$ = new_negate(p, $2);
                    }
                | tUMINUS_NUM tFLOAT            %prec tLOWEST
                    {
                      $$ = new_negate(p, $2);
                    }
                ;

variable        : tIDENTIFIER
                    {
                      $$ = new_lvar(p, $1);
                    }
                | tIVAR
                    {
                      $$ = new_ivar(p, $1);
                    }
                | tGVAR
                    {
                      $$ = new_gvar(p, $1);
                    }
                | tCVAR
                    {
                      $$ = new_cvar(p, $1);
                    }
                | tCONSTANT
                    {
                      $$ = new_const(p, $1);
                    }
                ;

var_lhs         : variable
                    {
                      assignable(p, $1);
                    }
                | tNUMPARAM
                    {
                      yyerror(&@1, p, "can't assign to numbered parameter");
                    }
                ;

var_ref         : variable
                    {
                      $$ = var_reference(p, $1);
                    }
                | tNUMPARAM
                    {
                      $$ = new_nvar(p, $1);
                    }
                | keyword_nil
                    {
                      $$ = new_nil(p);
                    }
                | keyword_self
                    {
                      $$ = new_self(p);
                    }
                | keyword_true
                    {
                      $$ = new_true(p);
                    }
                | keyword_false
                    {
                      $$ = new_false(p);
                    }
                | keyword__FILE__
                    {
                      const char *fn = mrb_sym_name_len(p->mrb, p->filename_sym, NULL);
                      if (!fn) {
                        fn = "(null)";
                      }
                      $$ = new_str(p, cons(cons(int_to_node(strlen(fn)), (node*)fn), (node*)NULL));
                    }
                | keyword__LINE__
                    {
                      char buf[16];

                      dump_int(p->lineno, buf);
                      $$ = new_int(p, buf, 10, 0);
                    }
                | keyword__ENCODING__
                    {
                      $$ = new_fcall(p, MRB_SYM(__ENCODING__), 0);
                    }
                ;

backref         : tNTH_REF
                | tBACK_REF
                ;

superclass      : /* term */
                    {
                      $$ = 0;
                    }
                | '<'
                    {
                      p->lstate = EXPR_BEG;
                      p->cmd_start = TRUE;
                    }
                  expr_value term
                    {
                      $$ = $3;
                    } /*
                | error term
                    {
                      yyerrok;
                      $$ = 0;
                    } */
                ;

f_opt_arglist_paren
                : f_arglist_paren
                | none
                ;

f_arglist_paren : '(' f_args rparen
                    {
                      $$ = $2;
                      p->lstate = EXPR_BEG;
                      p->cmd_start = TRUE;
                    }
                | '(' f_arg ',' tBDOT3 rparen
                    {
                      $$ = new_args_dots(p, $2);
                    }
                | '(' tBDOT3 rparen
                    {
                      $$ = new_args_dots(p, 0);
                    }
                ;

f_arglist       : f_arglist_paren
                | f_args term
                    {
                      $$ = $1;
                    }
                | f_arg ',' tBDOT3 term
                    {
                      $$ = new_args_dots(p, $1);
                    }
                | tDOT3 term
                    {
                      $$ = new_args_dots(p, 0);
                    }
                ;

f_label         : tIDENTIFIER tLABEL_TAG
                    {
                      $$ = $1;
                      local_nest(p);
                      p->lstate = EXPR_MID;  /* make newlines significant after label */
                    }
                | tNUMPARAM tLABEL_TAG
                    {
                      $$ = intern_numparam($1);
                      local_nest(p);
                      p->lstate = EXPR_MID;  /* make newlines significant after label */
                    }
                ;

f_kw            : f_label arg
                    {
                      void_expr_error(p, $2);
                      $$ = new_kw_arg(p, $1, cons($2, locals_node(p)));
                      local_unnest(p);
                    }
                | f_label
                    {
                      $$ = new_kw_arg(p, $1, 0);
                      local_unnest(p);
                    }
                ;

f_block_kw      : f_label primary_value
                    {
                      void_expr_error(p, $2);
                      $$ = new_kw_arg(p, $1, cons($2, locals_node(p)));
                      local_unnest(p);
                    }
                | f_label
                    {
                      $$ = new_kw_arg(p, $1, 0);
                      local_unnest(p);
                    }
                ;

f_block_kwarg   : f_block_kw
                    {
                      $$ = list1($1);
                    }
                | f_block_kwarg ',' f_block_kw
                    {
                      $$ = push($1, $3);
                    }
                ;

f_kwarg         : f_kw
                    {
                      $$ = list1($1);
                    }
                | f_kwarg ',' f_kw
                    {
                      $$ = push($1, $3);
                    }
                ;

kwrest_mark     : tPOW
                | tDSTAR
                ;

f_kwrest        : kwrest_mark tIDENTIFIER
                    {
                      $$ = $2;
                    }
                | kwrest_mark
                    {
                      $$ = intern_op(pow);
                    }
                ;

args_tail       : f_kwarg ',' f_kwrest opt_f_block_arg
                    {
                      $$ = new_args_tail(p, $1, $3, $4);
                    }
                | f_kwarg opt_f_block_arg
                    {
                      $$ = new_args_tail(p, $1, 0, $2);
                    }
                | f_kwrest opt_f_block_arg
                    {
                      $$ = new_args_tail(p, 0, $1, $2);
                    }
                | f_block_arg
                    {
                      $$ = new_args_tail(p, 0, 0, $1);
                    }
                ;

opt_args_tail   : ',' args_tail
                    {
                      $$ = $2;
                    }
                | ','
                    {
                      $$ = new_args_tail(p, 0, 0, 0);
                    }
                | /* none */
                    {
                      $$ = new_args_tail(p, 0, 0, 0);
                    }
                ;

f_args          : f_arg ',' f_optarg ',' f_rest_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, $3, $5, 0, $6);
                    }
                | f_arg ',' f_optarg ',' f_rest_arg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, $3, $5, $7, $8);
                    }
                | f_arg ',' f_optarg opt_args_tail
                    {
                      $$ = new_args(p, $1, $3, 0, 0, $4);
                    }
                | f_arg ',' f_optarg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, $3, 0, $5, $6);
                    }
                | f_arg ',' f_rest_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, 0, $3, 0, $4);
                    }
                | f_arg ',' f_rest_arg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, 0, $3, $5, $6);
                    }
                | f_arg opt_args_tail
                    {
                      $$ = new_args(p, $1, 0, 0, 0, $2);
                    }
                | f_optarg ',' f_rest_arg opt_args_tail
                    {
                      $$ = new_args(p, 0, $1, $3, 0, $4);
                    }
                | f_optarg ',' f_rest_arg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, 0, $1, $3, $5, $6);
                    }
                | f_optarg opt_args_tail
                    {
                      $$ = new_args(p, 0, $1, 0, 0, $2);
                    }
                | f_optarg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, 0, $1, 0, $3, $4);
                    }
                | f_rest_arg opt_args_tail
                    {
                      $$ = new_args(p, 0, 0, $1, 0, $2);
                    }
                | f_rest_arg ',' f_arg opt_args_tail
                    {
                      $$ = new_args(p, 0, 0, $1, $3, $4);
                    }
                | args_tail
                    {
                      $$ = new_args(p, 0, 0, 0, 0, $1);
                    }
                | /* none */
                    {
                      local_add_f(p, 0);
                      $$ = new_args(p, 0, 0, 0, 0, 0);
                    }
                ;

f_bad_arg       : tCONSTANT
                    {
                      yyerror(&@1, p, "formal argument cannot be a constant");
                      $$ = 0;
                    }
                | tIVAR
                    {
                      yyerror(&@1, p, "formal argument cannot be an instance variable");
                      $$ = 0;
                    }
                | tGVAR
                    {
                      yyerror(&@1, p, "formal argument cannot be a global variable");
                      $$ = 0;
                    }
                | tCVAR
                    {
                      yyerror(&@1, p, "formal argument cannot be a class variable");
                      $$ = 0;
                    }
                | tNUMPARAM
                    {
                      yyerror(&@1, p, "formal argument cannot be a numbered parameter");
                      $$ = 0;
                    }
                ;

f_norm_arg      : f_bad_arg
                    {
                      $$ = 0;
                    }
                | tIDENTIFIER
                    {
                      local_add_f(p, $1);
                      $$ = $1;
                    }
                ;

f_arg_item      : f_norm_arg
                    {
                      $$ = new_lvar(p, $1);
                    }
                | tLPAREN
                    {
                      $<nd>$ = local_switch(p);
                    }
                  f_margs rparen
                    {
                      $$ = new_marg(p, $3);
                      local_resume(p, $<nd>2);
                      local_add_f(p, 0);
                    }
                ;

f_arg           : f_arg_item
                    {
                      $$ = list1($1);
                    }
                | f_arg ',' f_arg_item
                    {
                      $$ = push($1, $3);
                    }
                ;

f_opt_asgn      : tIDENTIFIER '='
                    {
                      local_add_f(p, $1);
                      local_nest(p);
                      $$ = $1;
                    }
                ;

f_opt           : f_opt_asgn arg
                    {
                      void_expr_error(p, $2);
                      $$ = cons(sym_to_node($1), cons($2, locals_node(p)));
                      local_unnest(p);
                    }
                ;

f_block_opt     : f_opt_asgn primary_value
                    {
                      void_expr_error(p, $2);
                      $$ = cons(sym_to_node($1), cons($2, locals_node(p)));
                      local_unnest(p);
                    }
                ;

f_block_optarg  : f_block_opt
                    {
                      $$ = list1($1);
                    }
                | f_block_optarg ',' f_block_opt
                    {
                      $$ = push($1, $3);
                    }
                ;

f_optarg        : f_opt
                    {
                      $$ = list1($1);
                    }
                | f_optarg ',' f_opt
                    {
                      $$ = push($1, $3);
                    }
                ;

restarg_mark    : '*'
                | tSTAR
                ;

f_rest_arg      : restarg_mark tIDENTIFIER
                    {
                      local_add_f(p, $2);
                      $$ = $2;
                    }
                | restarg_mark
                    {
                      $$ = intern_op(mul);
                      local_add_f(p, $$);
                    }
                ;

blkarg_mark     : '&'
                | tAMPER
                ;

f_block_arg     : blkarg_mark tIDENTIFIER
                    {
                      $$ = $2;
                    }
                | blkarg_mark keyword_nil
                    {
                      $$ = MRB_SYM(nil);
                    }
                | blkarg_mark
                    {
                      $$ = intern_op(and);
                    }
                ;

opt_f_block_arg : ',' f_block_arg
                    {
                      $$ = $2;
                    }
                | ','
                    {
                      $$ = 0;
                    }
                | none
                    {
                      $$ = 0;
                    }
                ;

singleton       : var_ref
                    {
                      prohibit_literals(p, $1);
                      $$ = $1;
                      if (!$$) $$ = new_nil(p);
                    }
                | '(' {p->lstate = EXPR_BEG;} expr rparen
                    {
                      prohibit_literals(p, $3);
                      $$ = $3;
                    }
                ;

assoc_list      : none
                | assocs trailer
                    {
                      $$ = $1;
                    }
                ;

assocs          : assoc
                    {
                      $$ = list1($1);
                    }
                | assocs comma assoc
                    {
                      $$ = push($1, $3);
                    }
                ;

assoc           : arg tASSOC arg
                    {
                      void_expr_error(p, $1);
                      void_expr_error(p, $3);
                      $$ = cons($1, $3);
                    }
                | tIDENTIFIER tLABEL_TAG arg
                    {
                      void_expr_error(p, $3);
                      $$ = cons(new_sym(p, $1), $3);
                    }
                | tIDENTIFIER tLABEL_TAG
                    {
                      $$ = cons(new_sym(p, $1), label_reference(p, $1));
                    }
                | tNUMPARAM tLABEL_TAG
                    {
                      mrb_sym sym = intern_numparam($1);
                      $$ = cons(new_sym(p, sym), label_reference(p, sym));
                    }
                | tNUMPARAM tLABEL_TAG arg
                    {
                      void_expr_error(p, $3);
                      $$ = cons(new_sym(p, intern_numparam($1)), $3);
                    }
                | string_fragment tLABEL_TAG arg
                    {
                      void_expr_error(p, $3);
                      if ($1->cdr) {
                        /* Multiple fragments - create dynamic symbol */
                        $$ = cons(new_dsym(p, $1), $3);
                      }
                      else if (node_to_int($1->car->car) < 0) {
                        /* Single fragment but it's an expression (-1 . node) - create dynamic symbol */
                        $$ = cons(new_dsym(p, $1), $3);
                      }
                      else {
                        /* Single string fragment - create simple symbol */
                        $$ = cons(new_sym(p, new_strsym(p, $1->car)), $3);
                      }
                    }
                | tDSTAR arg
                    {
                      void_expr_error(p, $2);
                      $$ = cons(new_kw_rest_args(p, 0), $2);
                    }
                | tDSTAR
                    {
                      $$ = cons(new_kw_rest_args(p, 0), new_lvar(p, intern_op(pow)));
                    }
                ;

operation       : tIDENTIFIER
                | tCONSTANT
                | tFID
                ;

operation2      : tIDENTIFIER
                | tCONSTANT
                | tFID
                | op
                ;

operation3      : tIDENTIFIER
                | tFID
                | op
                ;

dot_or_colon    : '.'
                | tCOLON2
                ;

call_op         : '.'
                    {
                      $$ = '.';
                    }
                | tANDDOT
                    {
                      $$ = 0;
                    }
                ;

call_op2        : call_op
                | tCOLON2
                    {
                      $$ = tCOLON2;
                    }
                ;

opt_terms       : /* none */
                | terms
                ;

opt_nl          : /* none */
                | opt_nl nl
                ;

rparen          : opt_terms ')'
                ;

trailer         : /* none */
                | terms
                | comma
                ;

term            : ';' {yyerrok;}
                | nl
                ;

nl              : '\n'
                    {
                      p->lineno += $<num>1;
                      p->column = 0;
                    }
                | heredoc_body
                ;

terms           : term
                | terms term
                ;

none            : /* none */
                    {
                      $$ = 0;
                    }
                ;
%%
#define pylval  (*((YYSTYPE*)(p->ylval)))

static void
yyerror(void *lp, parser_state *p, const char *s)
{
  char* c;
  size_t n;

  if (! p->capture_errors) {
#ifndef MRB_NO_STDIO
    if (p->filename_sym) {
      const char *filename = mrb_sym_name_len(p->mrb, p->filename_sym, NULL);
      fprintf(stderr, "%s:%d:%d: %s\n", filename, p->lineno, p->column, s);
    }
    else {
      fprintf(stderr, "line %d:%d: %s\n", p->lineno, p->column, s);
    }
#endif
  }
  else if (p->nerr < sizeof(p->error_buffer) / sizeof(p->error_buffer[0])) {
    n = strlen(s);
    c = (char*)parser_palloc(p, n + 1);
    memcpy(c, s, n + 1);
    p->error_buffer[p->nerr].message = c;
    p->error_buffer[p->nerr].lineno = p->lineno;
    p->error_buffer[p->nerr].column = p->column;
  }
  p->nerr++;
}

static void
yyerror_c(parser_state *p, const char *msg, char c)
{
  char buf[256];

  strncpy(buf, msg, sizeof(buf) - 2);
  buf[sizeof(buf) - 2] = '\0';
  strncat(buf, &c, 1);
  yyerror(NULL, p, buf);
}

static void
yywarning(parser_state *p, const char *s)
{
  char* c;
  size_t n;

  if (! p->capture_errors) {
#ifndef MRB_NO_STDIO
    if (p->filename_sym) {
      const char *filename = mrb_sym_name_len(p->mrb, p->filename_sym, NULL);
      fprintf(stderr, "%s:%d:%d: warning: %s\n", filename, p->lineno, p->column, s);
    }
    else {
      fprintf(stderr, "line %d:%d: warning: %s\n", p->lineno, p->column, s);
    }
#endif
  }
  else if (p->nwarn < sizeof(p->warn_buffer) / sizeof(p->warn_buffer[0])) {
    n = strlen(s);
    c = (char*)parser_palloc(p, n + 1);
    memcpy(c, s, n + 1);
    p->warn_buffer[p->nwarn].message = c;
    p->warn_buffer[p->nwarn].lineno = p->lineno;
    p->warn_buffer[p->nwarn].column = p->column;
  }
  p->nwarn++;
}

static void
yywarning_s(parser_state *p, const char *msg, const char *s)
{
  char buf[256];

  strncpy(buf, msg, sizeof(buf) - 1);
  buf[sizeof(buf) - 1] = '\0';
  strncat(buf, ": ", sizeof(buf) - strlen(buf) - 1);
  strncat(buf, s, sizeof(buf) - strlen(buf) - 1);
  yywarning(p, buf);
}

static void
backref_error(parser_state *p, node *n)
{
  int c;

  c = node_to_int(n->car);

  if (c == NODE_NTH_REF) {
    yyerror_c(p, "can't set variable $", (char)node_to_int(n->cdr)+'0');
  }
  else if (c == NODE_BACK_REF) {
    yyerror_c(p, "can't set variable $", (char)node_to_int(n->cdr));
  }
  else {
    yyerror(NULL, p, "Internal error in backref_error()");
  }
}

static void
void_expr_error(parser_state *p, node *n)
{
  if (n == NULL) return;

  /* Check if this is a variable-sized node first */
  struct mrb_ast_var_header *header = (struct mrb_ast_var_header*)n;
  if (header) {
    /* Handle variable-sized nodes */
    switch ((enum node_type)header->node_type) {
    case NODE_BREAK:
    case NODE_RETURN:
    case NODE_NEXT:
    case NODE_REDO:
    case NODE_RETRY:
      yyerror(NULL, p, "void value expression");
      return;
    case NODE_AND:
    case NODE_OR:
      {
        struct mrb_ast_and_node *and_n = (struct mrb_ast_and_node*)n;
        void_expr_error(p, (node*)and_n->left);
        void_expr_error(p, (node*)and_n->right);
      }
      return;
    case NODE_STMTS:
      {
        struct mrb_ast_stmts_node *stmts = (struct mrb_ast_stmts_node*)n;
        node *last = stmts->stmts;
        if (last) {
          /* Find the last statement in the cons list */
          while (last->cdr) {
            last = last->cdr;
          }
          void_expr_error(p, last->car);
        }
      }
      return;
    case NODE_BEGIN:
      {
        struct mrb_ast_begin_node *begin_n = (struct mrb_ast_begin_node*)n;
        if (begin_n->body) {
          void_expr_error(p, (node*)begin_n->body);
        }
      }
      return;
    default:
      /* Other variable-sized nodes are OK */
      return;
    }
  }

  /* Should not reach here - all nodes should be variable-sized now */
}

static void pushback(parser_state *p, int c);
static mrb_bool peeks(parser_state *p, const char *s);
static mrb_bool skips(parser_state *p, const char *s);

static inline int
nextc0(parser_state *p)
{
  if (p->s && p->s < p->send) {
    return (unsigned char)*p->s++;
  }
  else {
#ifndef MRB_NO_STDIO
    int c;

    if (p->f) {
      c = fgetc(p->f);
      if (!feof(p->f)) return c;
    }
#endif
    return -1;
  }
}

static inline int
nextc(parser_state *p)
{
  int c;

  if (p->pb) {
    node *tmp;

    c = node_to_int(p->pb->car);
    tmp = p->pb;
    p->pb = p->pb->cdr;
    cons_free(tmp);
  }
  else {
    c = nextc0(p);
    if (c < 0) goto eof;
  }
  if (c >= 0) {
    p->column++;
  }
  if (c == '\r') {
    const int lf = nextc0(p);
    if (lf == '\n') {
      return '\n';
    }
    if (lf > 0) pushback(p, lf);
  }
  return c;

  eof:
  if (!p->cxt) return -1;
  else {
    if (p->cxt->partial_hook(p) < 0)
      return -1;                /* end of program(s) */
    return -2;                  /* end of a file in the program files */
  }
}

static void
pushback(parser_state *p, int c)
{
  if (c >= 0) {
    p->column--;
  }
  p->pb = cons(int_to_node(c), p->pb);
}

static void
skip(parser_state *p, char term)
{
  int c;

  for (;;) {
    c = nextc(p);
    if (c < 0) break;
    if (c == term) break;
  }
}

static int
peekc_n(parser_state *p, int n)
{
  node *list = 0;
  int c0;

  do {
    c0 = nextc(p);
    if (c0 == -1) return c0;    /* do not skip partial EOF */
    if (c0 >= 0) --p->column;
    list = push(list, int_to_node(c0));
  } while(n--);
  if (p->pb) {
    p->pb = append(list, p->pb);
  }
  else {
    p->pb = list;
  }
  return c0;
}

static mrb_bool
peek_n(parser_state *p, int c, int n)
{
  return peekc_n(p, n) == c && c >= 0;
}
#define peek(p,c) peek_n((p), (c), 0)

static mrb_bool
peeks(parser_state *p, const char *s)
{
  size_t len = strlen(s);

#ifndef MRB_NO_STDIO
  if (p->f) {
    int n = 0;
    while (*s) {
      if (!peek_n(p, *s++, n++)) return FALSE;
    }
    return TRUE;
  }
  else
#endif
    if (p->s && p->s + len <= p->send) {
      if (memcmp(p->s, s, len) == 0) return TRUE;
    }
  return FALSE;
}

static mrb_bool
skips(parser_state *p, const char *s)
{
  int c;

  for (;;) {
    /* skip until first char */
    for (;;) {
      c = nextc(p);
      if (c < 0) return FALSE;
      if (c == '\n') {
        p->lineno++;
        p->column = 0;
      }
      if (c == *s) break;
    }
    s++;
    if (peeks(p, s)) {
      size_t len = strlen(s);

      while (len--) {
        if (nextc(p) == '\n') {
          p->lineno++;
          p->column = 0;
        }
      }
      return TRUE;
    }
    else {
      s--;
    }
  }
  return FALSE;
}

static int
newtok(parser_state *p)
{
  if (p->tokbuf != p->buf) {
    mrbc_free(p->tokbuf);
    p->tokbuf = p->buf;
    p->tsiz = MRB_PARSER_TOKBUF_SIZE;
  }
  p->tidx = 0;
  return p->column - 1;
}

static void
tokadd(parser_state *p, int32_t c)
{
  char utf8[4];
  int i, len;

  /* mrb_assert(-0x10FFFF <= c && c <= 0xFF); */
  if (c >= 0) {
    /* Single byte from source or non-Unicode escape */
    utf8[0] = (char)c;
    len = 1;
  }
  else {
    /* Unicode character (negative c indicates codepoint) */
    len = (int)mrb_utf8_to_buf(utf8, (uint32_t)(-c));
  }
  if (p->tidx+len >= p->tsiz) {
    if (p->tsiz >= MRB_PARSER_TOKBUF_MAX) {
      p->tidx += len;
      return;
    }
    p->tsiz *= 2;
    if (p->tokbuf == p->buf) {
      p->tokbuf = (char*)mrbc_malloc(p->tsiz);
      memcpy(p->tokbuf, p->buf, MRB_PARSER_TOKBUF_SIZE);
    }
    else {
      p->tokbuf = (char*)mrbc_realloc(p->tokbuf, p->tsiz);
    }
  }
  for (i = 0; i < len; i++) {
    p->tokbuf[p->tidx++] = utf8[i];
  }
}

static int
toklast(parser_state *p)
{
  return p->tokbuf[p->tidx-1];
}

static void
tokfix(parser_state *p)
{
  if (p->tidx >= MRB_PARSER_TOKBUF_MAX) {
    p->tidx = MRB_PARSER_TOKBUF_MAX-1;
    yyerror(NULL, p, "string too long (truncated)");
  }
  p->tokbuf[p->tidx] = '\0';
}

static const char*
tok(parser_state *p)
{
  return p->tokbuf;
}

static int
toklen(parser_state *p)
{
  return p->tidx;
}

#define IS_ARG() (p->lstate == EXPR_ARG || p->lstate == EXPR_CMDARG)
#define IS_END() (p->lstate == EXPR_END || p->lstate == EXPR_ENDARG || p->lstate == EXPR_ENDFN)
#define IS_BEG() (p->lstate == EXPR_BEG || p->lstate == EXPR_MID || p->lstate == EXPR_VALUE || p->lstate == EXPR_CLASS)
#define IS_SPCARG(c) (IS_ARG() && space_seen && !ISSPACE(c))
#define IS_LABEL_POSSIBLE() ((p->lstate == EXPR_BEG && !cmd_state) || IS_ARG() || p->lstate == EXPR_VALUE)
#define IS_LABEL_SUFFIX(n) (peek_n(p, ':',(n)) && !peek_n(p, ':', (n)+1))

static int32_t
scan_oct(const int *start, int len, int *retlen)
{
  const int *s = start;
  int32_t retval = 0;

  /* mrb_assert(len <= 3) */
  while (len-- && *s >= '0' && *s <= '7') {
    retval <<= 3;
    retval |= *s++ - '0';
  }
  *retlen = (int)(s - start);

  return retval;
}

static int32_t
scan_hex(parser_state *p, const int *start, int len, int *retlen)
{
  static const char hexdigit[] = "0123456789abcdef0123456789ABCDEF";
  const int *s = start;
  uint32_t retval = 0;
  char *tmp;

  /* mrb_assert(len <= 8) */
  while (len-- && *s && (tmp = (char*)strchr(hexdigit, *s))) {
    retval <<= 4;
    retval |= (tmp - hexdigit) & 15;
    s++;
  }
  *retlen = (int)(s - start);

  return (int32_t)retval;
}

static int32_t
read_escape_unicode(parser_state *p, int limit)
{
  int buf[9];
  int i;
  int32_t hex;

  /* Look for opening brace */
  i = 0;
  buf[0] = nextc(p);
  if (buf[0] < 0) {
  eof:
    yyerror(NULL, p, "invalid escape character syntax");
    return -1;
  }
  if (ISXDIGIT(buf[0])) {
    /* \uxxxx form */
    for (i=1; i<limit; i++) {
      buf[i] = nextc(p);
      if (buf[i] < 0) goto eof;
      if (!ISXDIGIT(buf[i])) {
        pushback(p, buf[i]);
        break;
      }
    }
  }
  else {
    pushback(p, buf[0]);
  }
  hex = scan_hex(p, buf, i, &i);
  if (i == 0 || hex > 0x10FFFF || (hex & 0xFFFFF800) == 0xD800) {
    yyerror(NULL, p, "invalid Unicode code point");
    return -1;
  }
  return hex;
}

/* Return negative to indicate Unicode code point */
static int32_t
read_escape(parser_state *p)
{
  int32_t c;

  switch (c = nextc(p)) {
  case '\\':/* Backslash */
    return c;

  case 'n':/* newline */
    return '\n';

  case 't':/* horizontal tab */
    return '\t';

  case 'r':/* carriage-return */
    return '\r';

  case 'f':/* form-feed */
    return '\f';

  case 'v':/* vertical tab */
    return '\13';

  case 'a':/* alarm(bell) */
    return '\007';

  case 'e':/* escape */
    return 033;

  case '0': case '1': case '2': case '3': /* octal constant */
  case '4': case '5': case '6': case '7':
  {
    int buf[3];
    int i;

    buf[0] = c;
    for (i=1; i<3; i++) {
      buf[i] = nextc(p);
      if (buf[i] < 0) goto eof;
      if (buf[i] < '0' || '7' < buf[i]) {
        pushback(p, buf[i]);
        break;
      }
    }
    c = scan_oct(buf, i, &i);
  }
  return c;

  case 'x':     /* hex constant */
  {
    int buf[2];
    int i;

    for (i=0; i<2; i++) {
      buf[i] = nextc(p);
      if (buf[i] < 0) goto eof;
      if (!ISXDIGIT(buf[i])) {
        pushback(p, buf[i]);
        break;
      }
    }
    if (i == 0) {
      yyerror(NULL, p, "invalid hex escape");
      return -1;
    }
    return scan_hex(p, buf, i, &i);
  }

  case 'u':     /* Unicode */
    if (peek(p, '{')) {
      /* \u{xxxxxxxx} form */
      nextc(p);
      c = read_escape_unicode(p, 8);
      if (c < 0) return 0;
      if (nextc(p) != '}') goto eof;
    }
    else {
      c = read_escape_unicode(p, 4);
      if (c < 0) return 0;
    }
    return -c;

  case 'b':/* backspace */
    return '\010';

  case 's':/* space */
    return ' ';

  case 'M':
    if ((c = nextc(p)) != '-') {
      yyerror(NULL, p, "Invalid escape character syntax");
      pushback(p, c);
      return '\0';
    }
    if ((c = nextc(p)) == '\\') {
      return read_escape(p) | 0x80;
    }
    else if (c < 0) goto eof;
    else {
      return ((c & 0xff) | 0x80);
    }

  case 'C':
    if ((c = nextc(p)) != '-') {
      yyerror(NULL, p, "Invalid escape character syntax");
      pushback(p, c);
      return '\0';
    }
  case 'c':
    if ((c = nextc(p))== '\\') {
      c = read_escape(p);
    }
    else if (c == '?')
      return 0177;
    else if (c < 0) goto eof;
    return c & 0x9f;

    eof:
  case -1:
  case -2:                      /* end of a file */
    yyerror(NULL, p, "Invalid escape character syntax");
    return '\0';

  default:
    return c;
  }
}

static void
heredoc_count_indent(parser_heredoc_info *hinfo, const char *str, size_t len, size_t spaces, size_t *offset)
{
  size_t indent = 0;
  *offset = 0;
  for (size_t i = 0; i < len; i++) {
    size_t size;
    if (str[i] == '\n')
      break;
    else if (str[i] == '\t')
      size = 8;
    else if (ISSPACE(str[i]))
      size = 1;
    else
      break;
    size_t nindent = indent + size;
    if (nindent > spaces || nindent > hinfo->indent)
      break;
    indent = nindent;
    *offset += 1;
  }
}

static void
heredoc_remove_indent(parser_state *p, parser_heredoc_info *hinfo)
{
  if (!hinfo->remove_indent || hinfo->indent == 0)
    return;
  node *indented, *n, *pair, *escaped, *nspaces;
  const char *str;
  size_t len, spaces, offset, start, end;
  indented = hinfo->indented;
  while (indented) {
    n = indented->car;
    pair = n->car;
    len = (size_t)pair->car;
    str = (char*)pair->cdr;
    escaped = n->cdr->car;
    nspaces = n->cdr->cdr;
    if (escaped) {
      char *newstr = strndup(str, len);
      size_t newlen = 0;
      start = 0;
      while (start < len) {
        end = escaped ? (size_t)escaped->car : len;
        if (end > len) end = len;
        spaces = (size_t)nspaces->car;
        size_t esclen = end - start;
        heredoc_count_indent(hinfo, str + start, esclen, spaces, &offset);
        esclen -= offset;
        memcpy(newstr + newlen, str + start + offset, esclen);
        newlen += esclen;
        start = end;
        if (escaped)
          escaped = escaped->cdr;
        nspaces = nspaces->cdr;
      }
      if (newlen < len)
        newstr[newlen] = '\0';
      pair->car = (node*)newlen;
      pair->cdr = (node*)newstr;
    }
    else {
      spaces = (size_t)nspaces->car;
      heredoc_count_indent(hinfo, str, len, spaces, &offset);
      pair->car = (node*)(len - offset);
      pair->cdr = (node*)(str + offset);
    }
    indented = indented->cdr;
  }
}

static void
heredoc_push_indented(parser_state *p, parser_heredoc_info *hinfo, node *pair, node *escaped, node *nspaces, mrb_bool empty_line)
{
  hinfo->indented = push(hinfo->indented, cons(pair, cons(escaped, nspaces)));
  while (nspaces) {
    size_t tspaces = (size_t)nspaces->car;
    if ((hinfo->indent == ~0U || tspaces < hinfo->indent) && !empty_line)
      hinfo->indent = tspaces;
    nspaces = nspaces->cdr;
  }
}

static int
parse_string(parser_state *p)
{
  int c;
  string_type type = (string_type)p->lex_strterm->type;
  int nest_level = p->lex_strterm->level;
  int beg = p->lex_strterm->paren;
  int end = p->lex_strterm->term;
  parser_heredoc_info *hinfo = (type & STR_FUNC_HEREDOC) ? parsing_heredoc_info(p) : NULL;

  mrb_bool unindent = hinfo && hinfo->remove_indent;
  mrb_bool head = hinfo && hinfo->line_head;
  mrb_bool empty = TRUE;
  size_t spaces = 0;
  size_t pos = -1;
  node *escaped = NULL;
  node *nspaces = NULL;

  if (beg == 0) beg = -3;       /* should never happen */
  if (end == 0) end = -3;
  newtok(p);
  while ((c = nextc(p)) != end || nest_level != 0) {
    pos++;
    if (hinfo && (c == '\n' || c < 0)) {
      mrb_bool line_head;
      tokadd(p, '\n');
      tokfix(p);
      p->lineno++;
      p->column = 0;
      line_head = hinfo->line_head;
      hinfo->line_head = TRUE;
      if (line_head) {
        /* check whether end of heredoc */
        const char *s = tok(p);
        int len = toklen(p);
        if (hinfo->allow_indent) {
          while (ISSPACE(*s) && len > 0) {
            s++;
            len--;
          }
        }
        if (hinfo->term_len > 0 && len-1 == hinfo->term_len && strncmp(s, hinfo->term, len-1) == 0) {
          heredoc_remove_indent(p, hinfo);
          return tHEREDOC_END;
        }
      }
      if (c < 0) {
        char buf[256];
        const char s1[] = "can't find heredoc delimiter \"";
        const char s2[] = "\" anywhere before EOF";

        if (sizeof(s1)+sizeof(s2)+strlen(hinfo->term)+1 >= sizeof(buf)) {
          yyerror(NULL, p, "can't find heredoc delimiter anywhere before EOF");
        }
        else {
          strcpy(buf, s1);
          strcat(buf, hinfo->term);
          strcat(buf, s2);
          yyerror(NULL, p, buf);
        }
        return 0;
      }
      pylval.nd = new_str_tok(p);
      if (unindent && head) {
        nspaces = push(nspaces, int_to_node(spaces));
        heredoc_push_indented(p, hinfo, pylval.nd, escaped, nspaces, empty && line_head);
      }
      return tHD_STRING_MID;
    }
    if (unindent && empty) {
      if (c == '\t')
        spaces += 8;
      else if (ISSPACE(c))
        spaces++;
      else
        empty = FALSE;
    }
    if (c < 0) {
      yyerror(NULL, p, "unterminated string meets end of file");
      return 0;
    }
    else if (c == beg) {
      nest_level++;
      p->lex_strterm->level = nest_level;
    }
    else if (c == end) {
      nest_level--;
      p->lex_strterm->level = nest_level;
    }
    else if (c == '\\') {
      c = nextc(p);
      if (type & STR_FUNC_EXPAND) {
        if (c == end || c == beg) {
          tokadd(p, c);
        }
        else if (c == '\n') {
          p->lineno++;
          p->column = 0;
          if (unindent) {
            nspaces = push(nspaces, int_to_node(spaces));
            escaped = push(escaped, int_to_node(pos));
            pos--;
            empty = TRUE;
            spaces = 0;
          }
          if (type & STR_FUNC_ARRAY) {
            tokadd(p, '\n');
          }
        }
        else if (type & STR_FUNC_REGEXP) {
          tokadd(p, '\\');
          tokadd(p, c);
        }
        else if (c == 'u' && peek(p, '{')) {
          /* \u{xxxx xxxx xxxx} form */
          nextc(p);
          while (1) {
            do c = nextc(p); while (ISSPACE(c));
            if (c == '}') break;
            pushback(p, c);
            c = read_escape_unicode(p, 8);
            if (c < 0) break;
            tokadd(p, -c);
          }
          if (hinfo)
            hinfo->line_head = FALSE;
        }
        else {
          pushback(p, c);
          tokadd(p, read_escape(p));
          if (hinfo)
            hinfo->line_head = FALSE;
        }
      }
      else {
        if (c != beg && c != end) {
          if (c == '\n') {
            p->lineno++;
            p->column = 0;
          }
          if (!(c == '\\' || ((type & STR_FUNC_ARRAY) && ISSPACE(c)))) {
            tokadd(p, '\\');
          }
        }
        tokadd(p, c);
      }
      continue;
    }
    else if ((c == '#') && (type & STR_FUNC_EXPAND)) {
      c = nextc(p);
      if (c == '{') {
        tokfix(p);
        p->lstate = EXPR_BEG;
        p->cmd_start = TRUE;
        pylval.nd = new_str_tok(p);
        if (hinfo) {
          if (unindent && head) {
            nspaces = push(nspaces, int_to_node(spaces));
            heredoc_push_indented(p, hinfo, pylval.nd, escaped, nspaces, FALSE);
          }
          hinfo->line_head = FALSE;
          return tHD_STRING_PART;
        }
        return tSTRING_PART;
      }
      tokadd(p, '#');
      pushback(p, c);
      continue;
    }
    if ((type & STR_FUNC_ARRAY) && ISSPACE(c)) {
      if (toklen(p) == 0) {
        do {
          if (c == '\n') {
            p->lineno++;
            p->column = 0;
            heredoc_treat_nextline(p);
            if (p->parsing_heredoc != NULL) {
              return tHD_LITERAL_DELIM;
            }
          }
          c = nextc(p);
        } while (ISSPACE(c));
        pushback(p, c);
        return tLITERAL_DELIM;
      }
      else {
        pushback(p, c);
        tokfix(p);
        pylval.nd = new_str_tok(p);
        return tSTRING_MID;
      }
    }
    if (c == '\n') {
      p->lineno++;
      p->column = 0;
    }
    tokadd(p, c);
  }

  tokfix(p);
  p->lstate = EXPR_END;
  end_strterm(p);

  if (type & STR_FUNC_XQUOTE) {
    pylval.nd = new_str_tok(p);
    return tXSTRING;
  }

  if (type & STR_FUNC_REGEXP) {
    int f = 0;
    int re_opt;
    int pattern_len = toklen(p);
    char *s = strndup(tok(p), pattern_len);
    char flags[3];
    char *flag = flags;
    char enc = '\0';
    char *encp;
    char *dup;

    newtok(p);
    while (re_opt = nextc(p), re_opt >= 0 && ISALPHA(re_opt)) {
      switch (re_opt) {
      case 'i': f |= 1; break;
      case 'x': f |= 2; break;
      case 'm': f |= 4; break;
      case 'u': f |= 16; break;
      case 'n': f |= 32; break;
      case 'o': break;
      default: tokadd(p, re_opt); break;
      }
    }
    pushback(p, re_opt);
    if (toklen(p)) {
      char msg[128];

      strcpy(msg, "unknown regexp option");
      tokfix(p);
      if (toklen(p) > 1) {
        strcat(msg, "s");
      }
      strcat(msg, " - ");
      strncat(msg, tok(p), sizeof(msg) - strlen(msg) - 1);
      yyerror(NULL, p, msg);
    }
    if (f != 0) {
      if (f & 1) *flag++ = 'i';
      if (f & 2) *flag++ = 'x';
      if (f & 4) *flag++ = 'm';
      if (f & 16) enc = 'u';
      if (f & 32) enc = 'n';
    }
    if (flag > flags) {
      dup = strndup(flags, (size_t)(flag - flags));
    }
    else {
      dup = NULL;
    }
    if (enc) {
      encp = strndup(&enc, 1);
    }
    else {
      encp = NULL;
    }
    pylval.nd = cons(cons(int_to_node(pattern_len), (node*)s), cons((node*)dup, (node*)encp));

    return tREGEXP;
  }
  pylval.nd = new_str_tok(p);

  return tSTRING;
}

static int
number_literal_suffix(parser_state *p)
{
  int c, result = 0;
  node *list = 0;
  int column = p->column;
  int mask = NUM_SUFFIX_R|NUM_SUFFIX_I;

  while ((c = nextc(p)) != -1) {
    list = push(list, int_to_node(c));

    if ((mask & NUM_SUFFIX_I) && c == 'i') {
      result |= (mask & NUM_SUFFIX_I);
      mask &= ~NUM_SUFFIX_I;
      /* r after i, rational of complex is disallowed */
      mask &= ~NUM_SUFFIX_R;
      continue;
    }
    if ((mask & NUM_SUFFIX_R) && c == 'r') {
      result |= (mask & NUM_SUFFIX_R);
      mask &= ~NUM_SUFFIX_R;
      continue;
    }
    if (!ISASCII(c) || ISALPHA(c) || c == '_') {
      p->column = column;
      if (p->pb) {
        p->pb = append(list, p->pb);
      }
      else {
        p->pb = list;
      }
      return 0;
    }
    pushback(p, c);
    break;
  }
  return result;
}

static int
heredoc_identifier(parser_state *p)
{
  int c;
  int type = str_heredoc;
  mrb_bool indent = FALSE;
  mrb_bool squiggly = FALSE;
  mrb_bool quote = FALSE;
  node *newnode;
  parser_heredoc_info *info;

  c = nextc(p);
  if (ISSPACE(c) || c == '=') {
    pushback(p, c);
    return 0;
  }
  if (c == '-' || c == '~') {
    if (c == '-')
      indent = TRUE;
    if (c == '~')
      squiggly = TRUE;
    c = nextc(p);
  }
  if (c == '\'' || c == '"') {
    int term = c;
    if (c == '\'')
      quote = TRUE;
    newtok(p);
    while ((c = nextc(p)) >= 0 && c != term) {
      if (c == '\n') {
        c = -1;
        break;
      }
      tokadd(p, c);
    }
    if (c < 0) {
      yyerror(NULL, p, "unterminated here document identifier");
      return 0;
    }
  }
  else {
    if (c < 0) {
      return 0;                 /* missing here document identifier */
    }
    if (! identchar(c)) {
      pushback(p, c);
      if (indent) pushback(p, '-');
      if (squiggly) pushback(p, '~');
      return 0;
    }
    newtok(p);
    do {
      tokadd(p, c);
    } while ((c = nextc(p)) >= 0 && identchar(c));
    pushback(p, c);
  }
  tokfix(p);
  newnode = new_heredoc(p, &info);
  info->term = strndup(tok(p), toklen(p));
  info->term_len = toklen(p);
  if (! quote)
    type |= STR_FUNC_EXPAND;
  info->type = (string_type)type;
  info->allow_indent = indent || squiggly;
  info->remove_indent = squiggly;
  info->indent = ~0U;
  info->indented = NULL;
  info->line_head = TRUE;
  info->doc = NULL;
  p->heredocs_from_nextline = push(p->heredocs_from_nextline, newnode);
  p->lstate = EXPR_END;

  pylval.nd = newnode;
  return tHEREDOC_BEG;
}

static int
arg_ambiguous(parser_state *p)
{
  yywarning(p, "ambiguous first argument; put parentheses or even spaces");
  return 1;
}

#include "lex.def"

static int
parser_yylex(parser_state *p)
{
  int32_t c;
  int nlines = 1;
  int space_seen = 0;
  int cmd_state;
  enum mrb_lex_state_enum last_state;
  int token_column;

  /* Early termination if too many errors - prevents DoS from malformed input */
  if (p->nerr > 10) {
    return 0;  /* EOF */
  }

  if (p->lex_strterm) {
    if (is_strterm_type(p, STR_FUNC_HEREDOC)) {
      if (p->parsing_heredoc != NULL)
        return parse_string(p);
    }
    else
      return parse_string(p);
  }
  cmd_state = p->cmd_start;
  p->cmd_start = FALSE;
  retry:
  last_state = p->lstate;
  switch (c = nextc(p)) {
  case '\004':  /* ^D */
  case '\032':  /* ^Z */
  case '\0':    /* NUL */
  case -1:      /* end of script. */
    if (p->heredocs_from_nextline)
      goto maybe_heredoc;
    return 0;

  /* white spaces */
  case ' ': case '\t': case '\f': case '\r':
  case '\13':   /* '\v' */
    space_seen = 1;
    goto retry;

  case '#':     /* it's a comment */
    skip(p, '\n');
    /* fall through */
  case -2:      /* end of a file */
  case '\n':
  maybe_heredoc:
    heredoc_treat_nextline(p);
    p->column = 0;
    switch (p->lstate) {
    case EXPR_BEG:
    case EXPR_FNAME:
    case EXPR_DOT:
    case EXPR_CLASS:
    case EXPR_VALUE:
      p->lineno++;
      if (p->parsing_heredoc != NULL) {
        if (p->lex_strterm) {
          return parse_string(p);
        }
      }
      goto retry;
    default:
      break;
    }
    if (p->parsing_heredoc != NULL) {
      pylval.num = nlines;
      return '\n';
    }
    while ((c = nextc(p))) {
      switch (c) {
      case ' ': case '\t': case '\f': case '\r':
      case '\13': /* '\v' */
        space_seen = 1;
        break;
      case '#': /* comment as a whitespace */
        skip(p, '\n');
        nlines++;
        break;
      case '.':
        if (!peek(p, '.')) {
          pushback(p, '.');
          p->lineno+=nlines; nlines=1;
          goto retry;
        }
        pushback(p, c);
        goto normal_newline;
      case '&':
        if (peek(p, '.')) {
          pushback(p, '&');
          p->lineno+=nlines; nlines=1;
          goto retry;
        }
        pushback(p, c);
        goto normal_newline;
      case -1:                  /* EOF */
      case -2:                  /* end of a file */
        goto normal_newline;
      default:
        pushback(p, c);
        goto normal_newline;
      }
    }
  normal_newline:
    p->cmd_start = TRUE;
    p->lstate = EXPR_BEG;
    pylval.num = nlines;
    return '\n';

  case '*':
    if ((c = nextc(p)) == '*') {
      if ((c = nextc(p)) == '=') {
        pylval.id = intern_op(pow);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      if (IS_SPCARG(c)) {
        yywarning(p, "'**' interpreted as argument prefix");
        c = tDSTAR;
      }
      else if (IS_BEG()) {
        c = tDSTAR;
      }
      else {
        c = tPOW; /* "**", "argument prefix" */
      }
    }
    else {
      if (c == '=') {
        pylval.id = intern_op(mul);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      if (IS_SPCARG(c)) {
        yywarning(p, "'*' interpreted as argument prefix");
        c = tSTAR;
      }
      else if (IS_BEG()) {
        c = tSTAR;
      }
      else {
        c = '*';
      }
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    return c;

  case '!':
    c = nextc(p);
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
      if (c == '@') {
        return '!';
      }
    }
    else {
      p->lstate = EXPR_BEG;
    }
    if (c == '=') {
      return tNEQ;
    }
    if (c == '~') {
      return tNMATCH;
    }
    pushback(p, c);
    return '!';

  case '=':
    if (p->column == 1) {
      static const char begin[] = "begin";
      static const char end[] = "\n=end";
      if (peeks(p, begin)) {
        c = peekc_n(p, sizeof(begin)-1);
        if (c < 0 || ISSPACE(c)) {
          do {
            if (!skips(p, end)) {
              yyerror(NULL, p, "embedded document meets end of file");
              return 0;
            }
            c = nextc(p);
          } while (!(c < 0 || ISSPACE(c)));
          if (c != '\n') skip(p, '\n');
          p->lineno+=nlines; nlines=1;
          p->column = 0;
          goto retry;
        }
      }
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    if ((c = nextc(p)) == '=') {
      if ((c = nextc(p)) == '=') {
        return tEQQ;
      }
      pushback(p, c);
      return tEQ;
    }
    if (c == '~') {
      return tMATCH;
    }
    else if (c == '>') {
      return tASSOC;
    }
    pushback(p, c);
    return '=';

  case '<':
    c = nextc(p);
    if (c == '<' &&
        p->lstate != EXPR_DOT &&
        p->lstate != EXPR_CLASS &&
        !IS_END() &&
        (!IS_ARG() || space_seen)) {
      int token = heredoc_identifier(p);
      if (token)
        return token;
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
      if (p->lstate == EXPR_CLASS) {
        p->cmd_start = TRUE;
      }
    }
    if (c == '=') {
      if ((c = nextc(p)) == '>') {
        return tCMP;
      }
      pushback(p, c);
      return tLEQ;
    }
    if (c == '<') {
      if ((c = nextc(p)) == '=') {
        pylval.id = intern_op(lshift);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      return tLSHFT;
    }
    pushback(p, c);
    return '<';

  case '>':
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    if ((c = nextc(p)) == '=') {
      return tGEQ;
    }
    if (c == '>') {
      if ((c = nextc(p)) == '=') {
        pylval.id = intern_op(rshift);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      return tRSHFT;
    }
    pushback(p, c);
    return '>';

  case '"':
    p->lex_strterm = new_strterm(p, str_dquote, '"', 0);
    return tSTRING_BEG;

  case '\'':
    p->lex_strterm = new_strterm(p, str_squote, '\'', 0);
    return parse_string(p);

  case '`':
    if (p->lstate == EXPR_FNAME) {
      p->lstate = EXPR_ENDFN;
      return '`';
    }
    if (p->lstate == EXPR_DOT) {
      if (cmd_state)
        p->lstate = EXPR_CMDARG;
      else
        p->lstate = EXPR_ARG;
      return '`';
    }
    p->lex_strterm = new_strterm(p, str_xquote, '`', 0);
    return tXSTRING_BEG;

  case '?':
    if (IS_END()) {
      p->lstate = EXPR_VALUE;
      return '?';
    }
    c = nextc(p);
    if (c < 0) {
      yyerror(NULL, p, "incomplete character syntax");
      return 0;
    }
    if (ISSPACE(c)) {
      if (!IS_ARG()) {
        int c2;
        switch (c) {
        case ' ':
          c2 = 's';
          break;
        case '\n':
          c2 = 'n';
          break;
        case '\t':
          c2 = 't';
          break;
        case '\v':
          c2 = 'v';
          break;
        case '\r':
          c2 = 'r';
          break;
        case '\f':
          c2 = 'f';
          break;
        default:
          c2 = 0;
          break;
        }
        if (c2) {
          char buf[256];
          char cc[] = { (char)c2, '\0' };

          strcpy(buf, "invalid character syntax; use ?\\");
          strncat(buf, cc, 2);
          yyerror(NULL, p, buf);
        }
      }
      ternary:
      pushback(p, c);
      p->lstate = EXPR_VALUE;
      return '?';
    }
    newtok(p);
    /* need support UTF-8 if configured */
    if ((ISALNUM(c) || c == '_')) {
      int c2 = nextc(p);
      pushback(p, c2);
      if ((ISALNUM(c2) || c2 == '_')) {
        goto ternary;
      }
    }
    if (c == '\\') {
      c = read_escape(p);
      tokadd(p, c);
    }
    else {
      tokadd(p, c);
    }
    tokfix(p);
    pylval.nd = new_str_tok(p);
    p->lstate = EXPR_END;
    return tCHAR;

  case '&':
    if ((c = nextc(p)) == '&') {
      p->lstate = EXPR_BEG;
      if ((c = nextc(p)) == '=') {
        pylval.id = intern_op(andand);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      return tANDOP;
    }
    else if (c == '.') {
      p->lstate = EXPR_DOT;
      return tANDDOT;
    }
    else if (c == '=') {
      pylval.id = intern_op(and);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    pushback(p, c);
    if (IS_SPCARG(c)) {
      yywarning(p, "'&' interpreted as argument prefix");
      c = tAMPER;
    }
    else if (IS_BEG()) {
      c = tAMPER;
    }
    else {
      c = '&';
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    return c;

  case '|':
    if ((c = nextc(p)) == '|') {
      p->lstate = EXPR_BEG;
      if ((c = nextc(p)) == '=') {
        pylval.id = intern_op(oror);
        p->lstate = EXPR_BEG;
        return tOP_ASGN;
      }
      pushback(p, c);
      return tOROP;
    }
    if (c == '=') {
      pylval.id = intern_op(or);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    pushback(p, c);
    return '|';

  case '+':
    c = nextc(p);
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
      if (c == '@') {
        return tUPLUS;
      }
      pushback(p, c);
      return '+';
    }
    if (c == '=') {
      pylval.id = intern_op(add);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    if (IS_BEG() || (IS_SPCARG(c) && arg_ambiguous(p))) {
      p->lstate = EXPR_BEG;
      pushback(p, c);
      if (c >= 0 && ISDIGIT(c)) {
        c = '+';
        goto start_num;
      }
      return tUPLUS;
    }
    p->lstate = EXPR_BEG;
    pushback(p, c);
    return '+';

  case '-':
    c = nextc(p);
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
      if (c == '@') {
        return tUMINUS;
      }
      pushback(p, c);
      return '-';
    }
    if (c == '=') {
      pylval.id = intern_op(sub);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    if (c == '>') {
      p->lstate = EXPR_ENDFN;
      return tLAMBDA;
    }
    if (IS_BEG() || (IS_SPCARG(c) && arg_ambiguous(p))) {
      p->lstate = EXPR_BEG;
      pushback(p, c);
      if (c >= 0 && ISDIGIT(c)) {
        return tUMINUS_NUM;
      }
      return tUMINUS;
    }
    p->lstate = EXPR_BEG;
    pushback(p, c);
    return '-';

  case '.':
    {
      int is_beg = IS_BEG();
      p->lstate = EXPR_MID;
      if ((c = nextc(p)) == '.') {
        if ((c = nextc(p)) == '.') {
          return is_beg ? tBDOT3 : tDOT3;
        }
        pushback(p, c);
        return is_beg ? tBDOT2 : tDOT2;
      }
      pushback(p, c);
      p->lstate = EXPR_BEG;
      if (c >= 0 && ISDIGIT(c)) {
        yyerror(NULL, p, "no .<digit> floating literal anymore; put 0 before dot");
      }
      p->lstate = EXPR_DOT;
      return '.';
    }

    start_num:
  case '0': case '1': case '2': case '3': case '4':
  case '5': case '6': case '7': case '8': case '9':
  {
    int is_float, seen_point, seen_e, nondigit;
    int suffix = 0;

    is_float = seen_point = seen_e = nondigit = 0;
    p->lstate = EXPR_END;
    newtok(p);
    if (c == '-') {
      tokadd(p, c);
      c = nextc(p);
    }
    else if (c == '+') {
      c = nextc(p);
    }
    if (c == '0') {
#define no_digits() do {yyerror(NULL, p,"numeric literal without digits"); return 0;} while (0)
      int start = toklen(p);
      c = nextc(p);
      if (c == 'x' || c == 'X') {
        /* hexadecimal */
        c = nextc(p);
        if (c >= 0 && ISXDIGIT(c)) {
          do {
            if (c == '_') {
              if (nondigit) break;
              nondigit = c;
              continue;
            }
            if (!ISXDIGIT(c)) break;
            nondigit = 0;
            tokadd(p, tolower(c));
          } while ((c = nextc(p)) >= 0);
        }
        pushback(p, c);
        tokfix(p);
        if (toklen(p) == start) {
          no_digits();
        }
        else if (nondigit) goto trailing_uc;
        suffix = number_literal_suffix(p);
        pylval.nd = new_int(p, tok(p), 16, suffix);
        return tINTEGER;
      }
      if (c == 'b' || c == 'B') {
        /* binary */
        c = nextc(p);
        if (c == '0' || c == '1') {
          do {
            if (c == '_') {
              if (nondigit) break;
              nondigit = c;
              continue;
            }
            if (c != '0' && c != '1') break;
            nondigit = 0;
            tokadd(p, c);
          } while ((c = nextc(p)) >= 0);
        }
        pushback(p, c);
        tokfix(p);
        if (toklen(p) == start) {
          no_digits();
        }
        else if (nondigit) goto trailing_uc;
        suffix = number_literal_suffix(p);
        pylval.nd = new_int(p, tok(p), 2, suffix);
        return tINTEGER;
      }
      if (c == 'd' || c == 'D') {
        /* decimal */
        c = nextc(p);
        if (c >= 0 && ISDIGIT(c)) {
          do {
            if (c == '_') {
              if (nondigit) break;
              nondigit = c;
              continue;
            }
            if (!ISDIGIT(c)) break;
            nondigit = 0;
            tokadd(p, c);
          } while ((c = nextc(p)) >= 0);
        }
        pushback(p, c);
        tokfix(p);
        if (toklen(p) == start) {
          no_digits();
        }
        else if (nondigit) goto trailing_uc;
        suffix = number_literal_suffix(p);
        pylval.nd = new_int(p, tok(p), 10, suffix);
        return tINTEGER;
      }
      if (c == '_') {
        /* 0_0 */
        goto octal_number;
      }
      if (c == 'o' || c == 'O') {
        /* prefixed octal */
        c = nextc(p);
        if (c < 0 || c == '_' || !ISDIGIT(c)) {
          no_digits();
        }
      }
      if (c >= '0' && c <= '7') {
        /* octal */
        octal_number:
        do {
          if (c == '_') {
            if (nondigit) break;
            nondigit = c;
            continue;
          }
          if (c < '0' || c > '9') break;
          if (c > '7') goto invalid_octal;
          nondigit = 0;
          tokadd(p, c);
        } while ((c = nextc(p)) >= 0);

        if (toklen(p) > start) {
          pushback(p, c);
          tokfix(p);
          if (nondigit) goto trailing_uc;
          suffix = number_literal_suffix(p);
          pylval.nd = new_int(p, tok(p), 8, suffix);
          return tINTEGER;
        }
        if (nondigit) {
          pushback(p, c);
          goto trailing_uc;
        }
      }
      if (c > '7' && c <= '9') {
        invalid_octal:
        yyerror(NULL, p, "Invalid octal digit");
      }
      else if (c == '.' || c == 'e' || c == 'E') {
        tokadd(p, '0');
      }
      else {
        pushback(p, c);
        suffix = number_literal_suffix(p);
        pylval.nd = new_int(p, "0", 10, suffix);
        return tINTEGER;
      }
    }

    for (;;) {
      switch (c) {
      case '0': case '1': case '2': case '3': case '4':
      case '5': case '6': case '7': case '8': case '9':
        nondigit = 0;
        tokadd(p, c);
        break;

      case '.':
        if (nondigit) goto trailing_uc;
        if (seen_point || seen_e) {
          goto decode_num;
        }
        else {
          int c0 = nextc(p);
          if (c0 < 0 || !ISDIGIT(c0)) {
            pushback(p, c0);
            goto decode_num;
          }
          c = c0;
        }
        tokadd(p, '.');
        tokadd(p, c);
        is_float++;
        seen_point++;
        nondigit = 0;
        break;

      case 'e':
      case 'E':
        if (nondigit) {
          pushback(p, c);
          c = nondigit;
          goto decode_num;
        }
        if (seen_e) {
          goto decode_num;
        }
        tokadd(p, c);
        seen_e++;
        is_float++;
        nondigit = c;
        c = nextc(p);
        if (c != '-' && c != '+') continue;
        tokadd(p, c);
        nondigit = c;
        break;

      case '_':       /* '_' in number just ignored */
        if (nondigit) goto decode_num;
        nondigit = c;
        break;

      default:
        goto decode_num;
      }
      c = nextc(p);
    }

    decode_num:
    pushback(p, c);
    if (nondigit) {
      trailing_uc:
      yyerror_c(p, "trailing non digit in number: ", (char)nondigit);
    }
    tokfix(p);
    if (is_float) {
#ifdef MRB_NO_FLOAT
      yywarning_s(p, "floating-point numbers are not supported", tok(p));
      pylval.nd = new_int(p, "0", 10, 0);
      return tINTEGER;
#else
      double d;

      if (!mrb_read_float(tok(p), NULL, &d)) {
        yywarning_s(p, "corrupted float value", tok(p));
      }
      suffix = number_literal_suffix(p);
      if (seen_e && (suffix & NUM_SUFFIX_R)) {
        pushback(p, 'r');
        suffix &= ~NUM_SUFFIX_R;
      }
      pylval.nd = new_float(p, tok(p), suffix);
      return tFLOAT;
#endif
    }
    suffix = number_literal_suffix(p);
    pylval.nd = new_int(p, tok(p), 10, suffix);
    return tINTEGER;
  }

  case ')':
  case ']':
    p->paren_nest--;
    /* fall through */
  case '}':
    COND_LEXPOP();
    CMDARG_LEXPOP();
    if (c == ')')
      p->lstate = EXPR_ENDFN;
    else
      p->lstate = EXPR_END;
    return c;

  case ':':
    c = nextc(p);
    if (c == ':') {
      if (IS_BEG() || p->lstate == EXPR_CLASS || IS_SPCARG(-1)) {
        p->lstate = EXPR_BEG;
        return tCOLON3;
      }
      p->lstate = EXPR_DOT;
      return tCOLON2;
    }
    if (!space_seen && IS_END()) {
      pushback(p, c);
      /* In pattern matching context, use EXPR_ARG so newlines are significant */
      p->lstate = p->in_kwarg ? EXPR_ARG : EXPR_BEG;
      return tLABEL_TAG;
    }
    if (IS_END() || ISSPACE(c) || c == '#') {
      pushback(p, c);
      p->lstate = EXPR_BEG;
      return ':';
    }
    pushback(p, c);
    p->lstate = EXPR_FNAME;
    return tSYMBEG;

  case '/':
    if (IS_BEG()) {
      p->lex_strterm = new_strterm(p, str_regexp, '/', 0);
      return tREGEXP_BEG;
    }
    if ((c = nextc(p)) == '=') {
      pylval.id = intern_op(div);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    pushback(p, c);
    if (IS_SPCARG(c)) {
      p->lex_strterm = new_strterm(p, str_regexp, '/', 0);
      return tREGEXP_BEG;
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    return '/';

  case '^':
    if ((c = nextc(p)) == '=') {
      pylval.id = intern_op(xor);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    pushback(p, c);
    return '^';

  case ';':
    p->lstate = EXPR_BEG;
    return ';';

  case ',':
    p->lstate = EXPR_BEG;
    return ',';

  case '~':
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      if ((c = nextc(p)) != '@') {
        pushback(p, c);
      }
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    return '~';

  case '(':
    if (IS_BEG()) {
      c = tLPAREN;
    }
    else if (IS_SPCARG(-1)) {
      c = tLPAREN_ARG;
    }
    else if (p->lstate == EXPR_END && space_seen) {
      c = tLPAREN_ARG;
    }
    p->paren_nest++;
    COND_PUSH(0);
    CMDARG_PUSH(0);
    p->lstate = EXPR_BEG;
    return c;

  case '[':
    p->paren_nest++;
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
      p->paren_nest--;
      if ((c = nextc(p)) == ']') {
        if ((c = nextc(p)) == '=') {
          return tASET;
        }
        pushback(p, c);
        return tAREF;
      }
      pushback(p, c);
      return '[';
    }
    else if (IS_BEG()) {
      c = tLBRACK;
    }
    else if (IS_ARG() && space_seen) {
      c = tLBRACK;
    }
    p->lstate = EXPR_BEG;
    COND_PUSH(0);
    CMDARG_PUSH(0);
    return c;

  case '{':
    if (p->lpar_beg && p->lpar_beg == p->paren_nest) {
      p->lstate = EXPR_BEG;
      p->lpar_beg = 0;
      p->paren_nest--;
      COND_PUSH(0);
      CMDARG_PUSH(0);
      return tLAMBEG;
    }
    if (IS_ARG() || p->lstate == EXPR_END || p->lstate == EXPR_ENDFN)
      c = '{';          /* block (primary) */
    else if (p->lstate == EXPR_ENDARG)
      c = tLBRACE_ARG;  /* block (expr) */
    else
      c = tLBRACE;      /* hash */
    COND_PUSH(0);
    CMDARG_PUSH(0);
    p->lstate = EXPR_BEG;
    return c;

  case '\\':
    c = nextc(p);
    if (c == '\n') {
      p->lineno+=nlines; nlines=1;
      p->column = 0;
      space_seen = 1;
      goto retry; /* skip \\n */
    }
    pushback(p, c);
    return '\\';

  case '%':
    if (IS_BEG()) {
      int term;
      int paren;

      c = nextc(p);
      quotation:
      if (c < 0 || !ISALNUM(c)) {
        term = c;
        c = 'Q';
      }
      else {
        term = nextc(p);
        if (ISALNUM(term)) {
          yyerror(NULL, p, "unknown type of %string");
          return 0;
        }
      }
      if (c < 0 || term < 0) {
        yyerror(NULL, p, "unterminated quoted string meets end of file");
        return 0;
      }
      paren = term;
      if (term == '(') term = ')';
      else if (term == '[') term = ']';
      else if (term == '{') term = '}';
      else if (term == '<') term = '>';
      else paren = 0;

      switch (c) {
      case 'Q':
        p->lex_strterm = new_strterm(p, str_dquote, term, paren);
        return tSTRING_BEG;

      case 'q':
        p->lex_strterm = new_strterm(p, str_squote, term, paren);
        return parse_string(p);

      case 'W':
        p->lex_strterm = new_strterm(p, str_dword, term, paren);
        return tWORDS_BEG;

      case 'w':
        p->lex_strterm = new_strterm(p, str_sword, term, paren);
        return tWORDS_BEG;

      case 'x':
        p->lex_strterm = new_strterm(p, str_xquote, term, paren);
        return tXSTRING_BEG;

      case 'r':
        p->lex_strterm = new_strterm(p, str_regexp, term, paren);
        return tREGEXP_BEG;

      case 's':
        p->lex_strterm = new_strterm(p, str_ssym, term, paren);
        return tSYMBEG;

      case 'I':
        p->lex_strterm = new_strterm(p, str_dsymbols, term, paren);
        return tSYMBOLS_BEG;

      case 'i':
        p->lex_strterm = new_strterm(p, str_ssymbols, term, paren);
        return tSYMBOLS_BEG;

      default:
        yyerror(NULL, p, "unknown type of %string");
        return 0;
      }
    }
    if ((c = nextc(p)) == '=') {
      pylval.id = intern_op(mod);
      p->lstate = EXPR_BEG;
      return tOP_ASGN;
    }
    if (IS_SPCARG(c)) {
      goto quotation;
    }
    if (p->lstate == EXPR_FNAME || p->lstate == EXPR_DOT) {
      p->lstate = EXPR_ARG;
    }
    else {
      p->lstate = EXPR_BEG;
    }
    pushback(p, c);
    return '%';

  case '$':
    p->lstate = EXPR_END;
    token_column = newtok(p);
    c = nextc(p);
    if (c < 0) {
      yyerror(NULL, p, "incomplete global variable syntax");
      return 0;
    }
    switch (c) {
    case '_':     /* $_: last read line string */
      c = nextc(p);
      if (c >= 0 && identchar(c)) { /* if there is more after _ it is a variable */
        tokadd(p, '$');
        tokadd(p, c);
        break;
      }
      pushback(p, c);
      c = '_';
      /* fall through */
    case '~':     /* $~: match-data */
    case '*':     /* $*: argv */
    case '$':     /* $$: pid */
    case '?':     /* $?: last status */
    case '!':     /* $!: error string */
    case '@':     /* $@: error position */
    case '/':     /* $/: input record separator */
    case '\\':    /* $\: output record separator */
    case ';':     /* $;: field separator */
    case ',':     /* $,: output field separator */
    case '.':     /* $.: last read line number */
    case '=':     /* $=: ignorecase */
    case ':':     /* $:: load path */
    case '<':     /* $<: reading filename */
    case '>':     /* $>: default output handle */
    case '\"':    /* $": already loaded files */
      tokadd(p, '$');
      tokadd(p, c);
      tokfix(p);
      pylval.id = intern(tok(p), toklen(p));
      return tGVAR;

    case '-':
      tokadd(p, '$');
      tokadd(p, c);
      c = nextc(p);
      pushback(p, c);
      gvar:
      tokfix(p);
      pylval.id = intern(tok(p), toklen(p));
      return tGVAR;

    case '&':     /* $&: last match */
    case '`':     /* $`: string before last match */
    case '\'':    /* $': string after last match */
    case '+':     /* $+: string matches last pattern */
      if (last_state == EXPR_FNAME) {
        tokadd(p, '$');
        tokadd(p, c);
        goto gvar;
      }
      pylval.nd = new_back_ref(p, c);
      return tBACK_REF;

    case '1': case '2': case '3':
    case '4': case '5': case '6':
    case '7': case '8': case '9':
      do {
        tokadd(p, c);
        c = nextc(p);
      } while (c >= 0 && ISDIGIT(c));
      pushback(p, c);
      if (last_state == EXPR_FNAME) goto gvar;
      tokfix(p);
      {
        mrb_int n;
        if (!mrb_read_int(tok(p), NULL, NULL, &n)) {
          yywarning(p, "capture group index too big; always nil");
          return keyword_nil;
        }
        pylval.nd = new_nth_ref(p, (int)n);
      }
      return tNTH_REF;

    default:
      if (!identchar(c)) {
        pushback(p,  c);
        return '$';
      }
      /* fall through */
    case '0':
      tokadd(p, '$');
    }
    break;

    case '@':
      c = nextc(p);
      token_column = newtok(p);
      tokadd(p, '@');
      if (c == '@') {
        tokadd(p, '@');
        c = nextc(p);
      }
      if (c < 0) {
        if (p->tidx == 1) {
          yyerror(NULL, p, "incomplete instance variable syntax");
        }
        else {
          yyerror(NULL, p, "incomplete class variable syntax");
        }
        return 0;
      }
      else if (ISDIGIT(c)) {
        if (p->tidx == 1) {
          yyerror_c(p, "wrong instance variable name: @", c);
        }
        else {
          yyerror_c(p, "wrong class variable name: @@", c);
        }
        return 0;
      }
      if (!identchar(c)) {
        pushback(p, c);
        return '@';
      }
      break;

    case '_':
      token_column = newtok(p);
      break;

    default:
      if (!identchar(c)) {
        char buf[36];
        const char s[] = "Invalid char in expression: 0x";
        const char hexdigits[] = "0123456789ABCDEF";

        strcpy(buf, s);
        buf[sizeof(s)-1] = hexdigits[(c & 0xf0) >> 4];
        buf[sizeof(s)]   = hexdigits[(c & 0x0f)];
        buf[sizeof(s)+1] = 0;
        yyerror(NULL, p, buf);
        goto retry;
      }

      token_column = newtok(p);
      break;
  }

  do {
    tokadd(p, c);
    c = nextc(p);
    if (c < 0) break;
  } while (identchar(c));
  if (token_column == 0 && toklen(p) == 7 && (c < 0 || c == '\n') &&
      strncmp(tok(p), "__END__", toklen(p)) == 0)
    return -1;

  switch (tok(p)[0]) {
  case '@': case '$':
    pushback(p, c);
    break;
  default:
    if ((c == '!' || c == '?') && !peek(p, '=')) {
      tokadd(p, c);
    }
    else {
      pushback(p, c);
    }
  }
  tokfix(p);
  {
    int result = 0;

    switch (tok(p)[0]) {
    case '$':
      p->lstate = EXPR_END;
      result = tGVAR;
      break;
    case '@':
      p->lstate = EXPR_END;
      if (tok(p)[1] == '@')
        result = tCVAR;
      else
        result = tIVAR;
      break;

    case '_':
      if (toklen(p) == 2 && ISDIGIT(tok(p)[1]) && p->nvars) {
        int n = tok(p)[1] - '0';
        int nvar;

        if (n > 0) {
          nvar = node_to_int(p->nvars->car);
          if (nvar != -2) {     /* numbered parameters never appear on toplevel */
            pylval.num = n;
            p->lstate = EXPR_END;
            return tNUMPARAM;
          }
        }
      }
      /* fall through */
    default:
      if (toklast(p) == '!' || toklast(p) == '?') {
        result = tFID;
      }
      else {
        if (p->lstate == EXPR_FNAME) {
          if ((c = nextc(p)) == '=' && !peek(p, '~') && !peek(p, '>') &&
              (!peek(p, '=') || (peek_n(p, '>', 1)))) {
            result = tIDENTIFIER;
            tokadd(p, c);
            tokfix(p);
          }
          else {
            pushback(p, c);
          }
          if ((c = nextc(p)) == '=' && !peek(p, '~') && !peek(p, '>') &&
              (!peek(p, '=') || (peek_n(p, '>', 1)))) {
            result = tIDENTIFIER;
            tokadd(p, c);
            tokfix(p);
          }
          else {
            pushback(p, c);
          }
        }
        if (result == 0 && ISUPPER(tok(p)[0])) {
          result = tCONSTANT;
        }
        else {
          result = tIDENTIFIER;
        }
      }

      if (IS_LABEL_POSSIBLE()) {
        if (IS_LABEL_SUFFIX(0)) {
          p->lstate = EXPR_END;
          tokfix(p);
          pylval.id = intern(tok(p), toklen(p));
          return tIDENTIFIER;
        }
      }
      if (p->lstate != EXPR_DOT) {
        const struct kwtable *kw;

        /* See if it is a reserved word.  */
        kw = mrb_reserved_word(tok(p), toklen(p));
        if (kw) {
          enum mrb_lex_state_enum state = p->lstate;
          pylval.num = p->lineno;
          p->lstate = kw->state;
          if (state == EXPR_FNAME) {
            pylval.id = intern_cstr(kw->name);
            return kw->id[0];
          }
          if (p->lstate == EXPR_BEG) {
            p->cmd_start = TRUE;
          }
          if (kw->id[0] == keyword_do) {
            if (p->lpar_beg && p->lpar_beg == p->paren_nest) {
              p->lpar_beg = 0;
              p->paren_nest--;
              return keyword_do_LAMBDA;
            }
            if (COND_P()) return keyword_do_cond;
            if (CMDARG_P() && state != EXPR_CMDARG)
              return keyword_do_block;
            if (state == EXPR_ENDARG || state == EXPR_BEG)
              return keyword_do_block;
            return keyword_do;
          }
          if (kw->id[0] == keyword_in) {
            /* Set in_kwarg for pattern matching context */
            p->in_kwarg++;
          }
          if (state == EXPR_BEG || state == EXPR_VALUE || state == EXPR_CLASS)
            return kw->id[0];
          else {
            if (kw->id[0] != kw->id[1])
              p->lstate = EXPR_BEG;
            return kw->id[1];
          }
        }
      }

      if (IS_BEG() || p->lstate == EXPR_DOT || IS_ARG()) {
        if (cmd_state) {
          p->lstate = EXPR_CMDARG;
        }
        else {
          p->lstate = EXPR_ARG;
        }
      }
      else if (p->lstate == EXPR_FNAME) {
        p->lstate = EXPR_ENDFN;
      }
      else {
        p->lstate = EXPR_END;
      }
    }
    {
      mrb_sym ident = intern(tok(p), toklen(p));

      pylval.id = ident;
      if (last_state != EXPR_DOT && ISLOWER(tok(p)[0]) && local_var_p(p, ident)) {
        p->lstate = EXPR_END;
      }
    }
    return result;
  }
}

static int
yylex(void *lval, void *lp, parser_state *p)
{
  p->ylval = lval;
  return parser_yylex(p);
}

static void
parser_init_cxt(parser_state *p, mrb_ccontext *cxt)
{
  if (!cxt) return;
  if (cxt->filename) mrb_parser_set_filename(p, cxt->filename);
  if (cxt->lineno) p->lineno = cxt->lineno;
  if (cxt->syms) {
    int i;

    p->locals = cons(0,0);
    for (i=0; i<cxt->slen; i++) {
      local_add_f(p, cxt->syms[i]);
    }
  }
  p->capture_errors = cxt->capture_errors;
  p->no_optimize = cxt->no_optimize;
  p->no_ext_ops = cxt->no_ext_ops;
  p->no_return_value = cxt->no_return_value;
  p->upper = cxt->upper;
  if (cxt->partial_hook) {
    p->cxt = cxt;
  }
}

static void
parser_update_cxt(parser_state *p, mrb_ccontext *cxt)
{
  node *n, *n0;
  int i = 0;

  if (!cxt) return;
  if (!p->tree) return;
  if (!node_type_p(p->tree, NODE_SCOPE)) return;

  /* Extract locals from variable-sized NODE_SCOPE */
  struct mrb_ast_scope_node *scope = scope_node(p->tree);
  n0 = n = scope->locals;
  while (n) {
    i++;
    n = n->cdr;
  }
  cxt->syms = (mrb_sym*)mrbc_realloc(cxt->syms, i*sizeof(mrb_sym));
  cxt->slen = i;
  for (i=0, n=n0; n; i++,n=n->cdr) {
    cxt->syms[i] = node_to_sym(n->car);
  }
}

static void dump_node(mrb_state *mrb, node *tree, int offset);

MRB_API void
mrb_parser_parse(parser_state *p, mrb_ccontext *c)
{
  struct mrb_jmpbuf buf1;
  struct mrb_jmpbuf *prev = p->mrb->jmp;
  p->mrb->jmp = &buf1;

  MRB_TRY(p->mrb->jmp) {
    int n = 1;

    p->cmd_start = TRUE;
    p->in_def = p->in_single = 0;
    p->nerr = p->nwarn = 0;
    p->lex_strterm = NULL;
    parser_init_cxt(p, c);

    n = yyparse(p);
    if (n != 0 || p->nerr > 0) {
      p->tree = 0;
      p->mrb->jmp = prev;
      return;
    }
    parser_update_cxt(p, c);
    if (c && c->dump_result) {
      dump_node(p->mrb, p->tree, 0);
    }
  }
  MRB_CATCH(p->mrb->jmp) {
    p->nerr++;
    if (p->mrb->exc == NULL) {
      yyerror(NULL, p, "memory allocation error");
      p->nerr++;
      p->tree = 0;
    }
  }
  MRB_END_EXC(p->jmp);
  p->mrb->jmp = prev;
}

MRB_API parser_state*
mrb_parser_new(mrb_state *mrb)
{
  mempool *pool;
  parser_state *p;
  static const parser_state parser_state_zero = { 0 };

  pool = mempool_open();
  if (!pool) return NULL;
  p = (parser_state*)mempool_alloc(pool, sizeof(parser_state));
  if (!p) return NULL;

  *p = parser_state_zero;
  p->mrb = mrb;
  p->pool = pool;

  p->s = p->send = NULL;
#ifndef MRB_NO_STDIO
  p->f = NULL;
#endif

  p->cmd_start = TRUE;
  p->in_def = p->in_single = 0;

  p->capture_errors = FALSE;
  p->lineno = 1;
  p->column = 0;
#if defined(PARSER_TEST) || defined(PARSER_DEBUG)
  yydebug = 1;
#endif
  p->tsiz = MRB_PARSER_TOKBUF_SIZE;
  p->tokbuf = p->buf;

  p->lex_strterm = NULL;

  p->current_filename_index = -1;
  p->filename_table = NULL;
  p->filename_table_length = 0;

  return p;
}

MRB_API void
mrb_parser_free(parser_state *p) {
  if (p->tokbuf != p->buf) {
    mrbc_free(p->tokbuf);
  }
  mempool_close(p->pool);
}

MRB_API mrb_ccontext*
mrb_ccontext_new(mrb_state *mrb)
{
  static const mrb_ccontext cc_zero = { 0 };
  mrb_ccontext *cc = (mrb_ccontext*)mrbc_malloc(sizeof(mrb_ccontext));
  *cc = cc_zero;
  return cc;
}

MRB_API void
mrb_ccontext_free(mrb_state *mrb, mrb_ccontext *cxt)
{
  mrbc_free(cxt->filename);
  mrbc_free(cxt->syms);
  mrbc_free(cxt);
}

MRB_API const char*
mrb_ccontext_filename(mrb_state *mrb, mrb_ccontext *c, const char *s)
{
  if (s) {
    size_t len = strlen(s);
    char *p = (char*)mrbc_malloc(len + 1);

    if (p == NULL) return NULL;
    memcpy(p, s, len + 1);
    if (c->filename) {
      mrbc_free(c->filename);
    }
    c->filename = p;
  }
  return c->filename;
}

MRB_API void
mrb_ccontext_partial_hook(mrb_ccontext *c, int (*func)(struct mrb_parser_state*), void *data)
{
  c->partial_hook = func;
  c->partial_data = data;
}

MRB_API void
mrb_ccontext_cleanup_local_variables(mrb_ccontext *c)
{
  if (c->syms) {
    mrbc_free(c->syms);
    c->syms = NULL;
    c->slen = 0;
  }
  c->keep_lv = FALSE;
}

MRB_API void
mrb_parser_set_filename(struct mrb_parser_state *p, const char *f)
{
  mrb_sym sym;
  uint16_t i;
  mrb_sym* new_table;

  sym = mrb_intern_cstr(p->mrb, f);
  p->filename_sym = sym;
  /* Save current lineno so that AST nodes produced from a bison lookahead
     across the file boundary (in partial_hook) can recover the correct
     line in init_var_header instead of recording lineno=0. */
  p->prev_file_lineno = p->lineno;
  p->lineno = (p->filename_table_length > 0)? 0 : 1;

  for (i = 0; i < p->filename_table_length; i++) {
    if (p->filename_table[i] == sym) {
      p->current_filename_index = i;
      return;
    }
  }

  if (p->filename_table_length == UINT16_MAX) {
    yyerror(NULL, p, "too many files to compile");
    return;
  }
  p->current_filename_index = p->filename_table_length++;

  new_table = (mrb_sym*)parser_palloc(p, sizeof(mrb_sym) * p->filename_table_length);
  if (p->filename_table) {
    memmove(new_table, p->filename_table, sizeof(mrb_sym) * p->current_filename_index);
  }
  p->filename_table = new_table;
  p->filename_table[p->filename_table_length - 1] = sym;
}

MRB_API mrb_sym
mrb_parser_get_filename(struct mrb_parser_state* p, uint16_t idx) {
  if (idx >= p->filename_table_length) return 0;
  else {
    return p->filename_table[idx];
  }
}

#ifndef MRB_NO_STDIO
static struct mrb_parser_state *
mrb_parse_file_continue(mrb_state *mrb, FILE *f, const void *prebuf, size_t prebufsize, mrb_ccontext *c)
{
  parser_state *p;

  p = mrb_parser_new(mrb);
  if (!p) return NULL;
  if (prebuf) {
    p->s = (const char*)prebuf;
    p->send = (const char*)prebuf + prebufsize;
  }
  else {
    p->s = p->send = NULL;
  }
  p->f = f;

  mrb_parser_parse(p, c);
  return p;
}

MRB_API parser_state*
mrb_parse_file(mrb_state *mrb, FILE *f, mrb_ccontext *c)
{
  return mrb_parse_file_continue(mrb, f, NULL, 0, c);
}
#endif

MRB_API parser_state*
mrb_parse_nstring(mrb_state *mrb, const char *s, size_t len, mrb_ccontext *c)
{
  parser_state *p;

  p = mrb_parser_new(mrb);
  if (!p) return NULL;
  p->s = s;
  p->send = s + len;

  mrb_parser_parse(p, c);
  return p;
}

MRB_API parser_state*
mrb_parse_string(mrb_state *mrb, const char *s, mrb_ccontext *c)
{
  return mrb_parse_nstring(mrb, s, strlen(s), c);
}

MRB_API mrb_value
mrb_load_exec(mrb_state *mrb, struct mrb_parser_state *p, mrb_ccontext *c)
{
  struct RClass *target = mrb->object_class;
  struct RProc *proc;
  mrb_value v;
  mrb_int keep = 0;

  if (!p) {
    return mrb_undef_value();
  }
  if (!p->tree || p->nerr) {
    if (c) c->parser_nerr = p->nerr;
    if (p->capture_errors) {
      char buf[256];

      strcpy(buf, "line ");
      dump_int(p->error_buffer[0].lineno, buf+5);
      strcat(buf, ": ");
      strncat(buf, p->error_buffer[0].message, sizeof(buf) - strlen(buf) - 1);
      mrb->exc = mrb_obj_ptr(mrb_exc_new(mrb, E_SYNTAX_ERROR, buf, strlen(buf)));
      mrb_parser_free(p);
      return mrb_undef_value();
    }
    else {
      if (mrb->exc == NULL) {
        mrb->exc = mrb_obj_ptr(mrb_exc_new_lit(mrb, E_SYNTAX_ERROR, "syntax error"));
      }
      mrb_parser_free(p);
      return mrb_undef_value();
    }
  }
  proc = mrb_generate_code(mrb, p);
  mrb_parser_free(p);
  if (proc == NULL) {
    if (mrb->exc == NULL) {
      mrb->exc = mrb_obj_ptr(mrb_exc_new_lit(mrb, E_SCRIPT_ERROR, "codegen error"));
    }
    return mrb_undef_value();
  }
  if (c) {
    if (c->dump_result) mrb_codedump_all(mrb, proc);
    if (c->no_exec) return mrb_obj_value(proc);
    if (c->target_class) {
      target = c->target_class;
    }
    if (c->keep_lv) {
      keep = c->slen + 1;
    }
    else {
      c->keep_lv = TRUE;
    }
  }
  MRB_PROC_SET_TARGET_CLASS(proc, target);
  if (mrb->c->ci) {
    mrb_vm_ci_target_class_set(mrb->c->ci, target);
  }
  v = mrb_top_run(mrb, proc, mrb_top_self(mrb), keep);
  if (mrb->exc) return mrb_nil_value();
  return v;
}

#ifndef MRB_NO_STDIO
MRB_API mrb_value
mrb_load_file_cxt(mrb_state *mrb, FILE *f, mrb_ccontext *c)
{
  return mrb_load_exec(mrb, mrb_parse_file(mrb, f, c), c);
}

MRB_API mrb_value
mrb_load_file(mrb_state *mrb, FILE *f)
{
  return mrb_load_file_cxt(mrb, f, NULL);
}

#define DETECT_SIZE 64

/*
 * In order to be recognized as a `.mrb` file, the following three points must be satisfied:
 * - File starts with "RITE"
 * - At least `sizeof(struct rite_binary_header)` bytes can be read
 * - `NUL` is included in the first 64 bytes of the file
 */
MRB_API mrb_value
mrb_load_detect_file_cxt(mrb_state *mrb, FILE *fp, mrb_ccontext *c)
{
  union {
    char b[DETECT_SIZE];
    struct rite_binary_header h;
  } leading;
  size_t bufsize;

  if (mrb == NULL || fp == NULL) {
    return mrb_nil_value();
  }

  bufsize = fread(leading.b, sizeof(char), sizeof(leading), fp);
  if (bufsize < sizeof(leading.h) ||
      memcmp(leading.h.binary_ident, RITE_BINARY_IDENT, sizeof(leading.h.binary_ident)) != 0 ||
      memchr(leading.b, '\0', bufsize) == NULL) {
    return mrb_load_exec(mrb, mrb_parse_file_continue(mrb, fp, leading.b, bufsize, c), c);
  }
  else {
    mrb_int binsize = bin_to_uint32(leading.h.binary_size);
    mrb_value bin_obj = mrb_str_new(mrb, NULL, binsize);
    uint8_t *bin = (uint8_t*)RSTRING_PTR(bin_obj);
    if ((size_t)binsize > bufsize) {
      memcpy(bin, leading.b, bufsize);
      if (fread(bin + bufsize, binsize - bufsize, 1, fp) == 0) {
        binsize = bufsize;
        /* The error is reported by mrb_load_irep_buf_cxt() */
      }
    }

    mrb_value result = mrb_load_irep_buf_cxt(mrb, bin, binsize, c);
    if (mrb_string_p(bin_obj)) mrb_str_resize(mrb, bin_obj, 0);
    return result;
  }
}
#endif

MRB_API mrb_value
mrb_load_nstring_cxt(mrb_state *mrb, const char *s, size_t len, mrb_ccontext *c)
{
  return mrb_load_exec(mrb, mrb_parse_nstring(mrb, s, len, c), c);
}

MRB_API mrb_value
mrb_load_nstring(mrb_state *mrb, const char *s, size_t len)
{
  return mrb_load_nstring_cxt(mrb, s, len, NULL);
}

MRB_API mrb_value
mrb_load_string_cxt(mrb_state *mrb, const char *s, mrb_ccontext *c)
{
  return mrb_load_nstring_cxt(mrb, s, strlen(s), c);
}

MRB_API mrb_value
mrb_load_string(mrb_state *mrb, const char *s)
{
  return mrb_load_string_cxt(mrb, s, NULL);
}

#ifndef MRB_NO_STDIO

static void
dump_prefix(int offset, uint16_t lineno)
{
  printf("%05d ", lineno);
  while (offset--) {
    putc(' ', stdout);
    putc(' ', stdout);
  }
}

static void
dump_recur(mrb_state *mrb, node *tree, int offset)
{
  while (tree) {
    dump_node(mrb, tree->car, offset);
    tree = tree->cdr;
  }
}

static void
dump_locals(mrb_state *mrb, node *tree, int offset, uint16_t lineno)
{
  if (!tree || (!tree->car && !tree->cdr)) return;

  dump_prefix(offset, lineno);
  printf("locals:\n");
  dump_prefix(offset+1, lineno);
  while (tree) {
    if (tree->car) {
      mrb_sym sym = node_to_sym(tree->car);
      if (sym != 0) {
        const char *name = mrb_sym_name(mrb, sym);
        if (name && strlen(name) > 0 && name[0] != '!' && name[0] != '@' && name[0] != '$') {
          printf(" %s", mrb_sym_dump(mrb, sym));
        }
        else {
          printf(" (invalid symbol: %s)", name ? name : "(null)");
        }
      }
      else {
        printf(" (anonymous)");
      }
    }
    tree = tree->cdr;
  }
  printf("\n");
}

static void
dump_cpath(mrb_state *mrb, node *tree, int offset, uint16_t lineno)
{
  dump_prefix(offset, lineno);
  printf("cpath: ");
  if (!tree) {
    printf("(null)\n");
  }
  else if (node_to_int(tree->car) == 0) {
    printf("(null)\n");
  }
  else if (node_to_int(tree->car) == 1) {
    printf("Object\n");
  }
  else {
    printf("\n");
    dump_node(mrb, tree->car, offset+1);
  }
  dump_prefix(offset, lineno);
  printf("name: %s\n", mrb_sym_dump(mrb, node_to_sym(tree->cdr)));
}

/*
 * This function restores the GC arena on return.
 * For this reason, if a process that further generates an object is
 * performed at the caller, the string pointer returned as the return
 * value may become invalid.
 */
static const char*
str_dump(mrb_state *mrb, const char *str, int len)
{
  int ai = mrb_gc_arena_save(mrb);
  mrb_value s = mrb_str_new(mrb, str, (mrb_int)len);
  s = mrb_str_dump(mrb, s);
  mrb_gc_arena_restore(mrb, ai);
  return RSTRING_PTR(s);
}

static void
dump_str(mrb_state *mrb, node *n, int offset, uint16_t lineno)
{
  while (n) {
    dump_prefix(offset, lineno);
    int len = node_to_int(n->car->car);
    if (len >= 0) {
      printf("str: %s\n", str_dump(mrb, (char*)n->car->cdr, len));
    }
    else {
      printf("interpolation:\n");
      dump_node(mrb, n->car->cdr, offset+1);
    }
    n = n->cdr;
  }
}

static void
dump_args(mrb_state *mrb, struct mrb_ast_args *args, int offset, uint16_t lineno)
{
  if (args->mandatory_args) {
    dump_prefix(offset, lineno);
    printf("mandatory args:\n");
    dump_recur(mrb, args->mandatory_args, offset+1);
  }
  if (args->optional_args) {
    dump_prefix(offset, lineno);
    printf("optional args:\n");
    {
      node *n = args->optional_args;
      while (n) {
        dump_prefix(offset+1, lineno);
        printf("%s=\n", mrb_sym_name(mrb, node_to_sym(n->car->car)));
        dump_node(mrb, n->car->cdr, offset+2);
        n = n->cdr;
      }
    }
  }
  if (args->rest_arg) {
    mrb_sym rest = args->rest_arg;

    dump_prefix(offset, lineno);
    if (rest == MRB_OPSYM(mul))
      printf("rest=*\n");
    else
      printf("rest=*%s\n", mrb_sym_name(mrb, rest));
  }
  if (args->post_mandatory_args) {
    dump_prefix(offset, lineno);
    printf("post mandatory args:\n");
    dump_recur(mrb, args->post_mandatory_args, offset+1);
  }
  if (args->keyword_args) {
    dump_prefix(offset, lineno);
    printf("keyword args:\n");
    {
      node *n = args->keyword_args;
      while (n) {
        dump_prefix(offset+1, lineno);
        printf("%s:\n", mrb_sym_name(mrb, node_to_sym(n->car->car)));
        dump_node(mrb, n->car->cdr, offset+2);
        n = n->cdr;
      }
    }
  }
  if (args->kwrest_arg) {
    mrb_sym rest = args->kwrest_arg;

    dump_prefix(offset, lineno);
    if (rest == MRB_OPSYM(pow))
      printf("kwrest=**\n");
    else
      printf("kwrest=**%s\n", mrb_sym_name(mrb, rest));
  }
  if (args->block_arg) {
    mrb_sym blk = args->block_arg;

    dump_prefix(offset, lineno);
    if (blk == MRB_OPSYM(and))
      printf("blk=&\n");
    else if (blk == MRB_SYM(nil))
      printf("blk=&nil\n");
    else
      printf("blk=&%s\n", mrb_sym_name(mrb, blk));
  }
}

static void
dump_callargs(mrb_state *mrb, node *n, int offset, uint16_t lineno)
{
  if (!n) return;

  struct mrb_ast_callargs *args = (struct mrb_ast_callargs*)n;
  if (args->regular_args) {
    dump_prefix(offset+1, lineno);
    printf("args:\n");
    dump_recur(mrb, args->regular_args, offset+2);
  }
  if (args->keyword_args) {
    dump_prefix(offset+1, lineno);
    printf("kw_args:\n");
    node *kw = args->keyword_args;
    while (kw) {
      dump_prefix(offset+2, lineno);
      printf("key:\n");
      if (node_to_sym(kw->car->car) == MRB_OPSYM(pow)) {
        dump_prefix(offset+3, lineno);
        printf("**:\n");
      }
      else {
        dump_node(mrb, kw->car->car, offset+3);
      }
      dump_prefix(offset+2, lineno);
      printf("value:\n");
      dump_node(mrb, kw->car->cdr, offset+3);
      kw = kw->cdr;
    }
  }
  if (args->block_arg) {
    dump_prefix(offset+1, lineno);
    printf("block:\n");
    dump_node(mrb, args->block_arg, offset+2);
  }
}

#endif

void
dump_node(mrb_state *mrb, node *tree, int offset)
{
#ifndef MRB_NO_STDIO
  enum node_type nodetype;
  uint16_t lineno = 0;

  if (!tree) return;

  /* Extract line number from variable-sized node header */
  if (node_type(tree) != NODE_LAST) {
    lineno = ((struct mrb_ast_var_header*)tree)->lineno;
  }

  dump_prefix(offset, lineno);

  /* All nodes are now variable-sized nodes with headers */
  nodetype = node_type(tree);

  switch (nodetype) {
  /* Variable-sized node cases */
  case NODE_SCOPE:
    printf("NODE_SCOPE:\n");
    if (scope_node(tree)->locals) {
      dump_locals(mrb, scope_node(tree)->locals, offset+1, lineno);
    }
    if (scope_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, scope_node(tree)->body, offset+2);
    }
    break;

  case NODE_INT:
    printf("NODE_INT: %d\n", int_node(tree)->value);
    break;

  case NODE_BIGINT:
    printf("NODE_BIGINT: %s (base %d)\n", bigint_node(tree)->string, bigint_node(tree)->base);
    break;

  case NODE_FLOAT:
    printf("NODE_FLOAT: %s\n", float_node(tree)->value);
    break;

  case NODE_STR:
    printf("NODE_STR:\n");
    dump_str(mrb, str_node(tree)->list, offset+1, lineno);
    break;

  case NODE_XSTR:
    printf("NODE_XSTR:\n");
    dump_str(mrb, xstr_node(tree)->list, offset+1, lineno);
    break;

  case NODE_SYM:
    printf("NODE_SYM: %s\n", mrb_sym_dump(mrb, sym_node(tree)->symbol));
    break;

  case NODE_DSYM:
    printf("NODE_DSYM:\n");
    dump_str(mrb, str_node(tree)->list, offset+1, lineno);
    break;

  case NODE_LVAR:
    printf("NODE_LVAR: %s\n", mrb_sym_dump(mrb, var_node(tree)->symbol));
    break;

  case NODE_GVAR:
    printf("NODE_GVAR: %s\n", mrb_sym_dump(mrb, var_node(tree)->symbol));
    break;

  case NODE_IVAR:
    printf("NODE_IVAR: %s\n", mrb_sym_dump(mrb, var_node(tree)->symbol));
    break;

  case NODE_CVAR:
    printf("NODE_CVAR: %s\n", mrb_sym_dump(mrb, var_node(tree)->symbol));
    break;

  case NODE_NVAR:
    printf("NODE_NVAR: %d\n", nvar_node(tree)->num);
    break;

  case NODE_CONST:
    printf("NODE_CONST: %s\n", mrb_sym_dump(mrb, var_node(tree)->symbol));
    break;

  case NODE_CALL:
    printf("NODE_CALL: %s\n", mrb_sym_dump(mrb, call_node(tree)->method_name));
    if (call_node(tree)->receiver) {
      dump_prefix(offset+1, lineno);
      printf("receiver:\n");
      dump_node(mrb, call_node(tree)->receiver, offset+2);
    }
    if (call_node(tree)->args) {
      dump_callargs(mrb, call_node(tree)->args, offset, lineno);
    }
    break;

  case NODE_ARRAY:
    printf("NODE_ARRAY:\n");
    if (array_node(tree)->elements) {
      dump_recur(mrb, array_node(tree)->elements, offset+1);
    }
    break;

  case NODE_TRUE:
    printf("NODE_TRUE\n");
    break;

  case NODE_FALSE:
    printf("NODE_FALSE\n");
    break;

  case NODE_NIL:
    printf("NODE_NIL\n");
    break;

  case NODE_SELF:
    printf("NODE_SELF\n");
    break;

  case NODE_IF:
    printf("NODE_IF:\n");
    if (if_node(tree)->condition) {
      dump_prefix(offset+1, lineno);
      printf("cond:\n");
      dump_node(mrb, if_node(tree)->condition, offset+2);
    }
    if (if_node(tree)->then_body) {
      dump_prefix(offset+1, lineno);
      printf("then:\n");
      dump_node(mrb, if_node(tree)->then_body, offset+2);
    }
    if (if_node(tree)->else_body) {
      dump_prefix(offset+1, lineno);
      printf("else:\n");
      dump_node(mrb, if_node(tree)->else_body, offset+2);
    }
    break;

  case NODE_DEF:
    printf("NODE_DEF: %s\n", mrb_sym_dump(mrb, def_node(tree)->name));
    if (def_node(tree)->args) {
      dump_args(mrb, sdef_node(tree)->args, offset+1, lineno);
    }
    if (def_node(tree)->locals) {
      dump_locals(mrb, def_node(tree)->locals, offset+1, lineno);
    }
    if (def_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, def_node(tree)->body, offset+2);
    }
    break;

  case NODE_ASGN:
    printf("NODE_ASGN:\n");
    if (asgn_node(tree)->lhs) {
      dump_prefix(offset+1, lineno);
      printf("lhs:\n");
      dump_node(mrb, asgn_node(tree)->lhs, offset+2);
    }
    if (asgn_node(tree)->rhs) {
      dump_prefix(offset+1, lineno);
      printf("rhs:\n");
      dump_node(mrb, asgn_node(tree)->rhs, offset+2);
    }
    break;

  case NODE_MASGN:
  case NODE_MARG:
    printf("%s:\n", node_type(tree) == NODE_MASGN ? "NODE_MASGN" : "NODE_MARG");
    /* Handle pre-splat variables */
    if (masgn_node(tree)->pre) {
      dump_prefix(offset+1, lineno);
      printf("pre:\n");
      dump_recur(mrb, masgn_node(tree)->pre, offset+2);
    }
    /* Handle splat variable (can be -1 sentinel for anonymous splat) */
    if (masgn_node(tree)->rest) {
      if ((intptr_t)masgn_node(tree)->rest == -1) {
        dump_prefix(offset+1, lineno);
        printf("rest: *<anonymous>\n");
      }
      else {
        dump_prefix(offset+1, lineno);
        printf("rest:\n");
        dump_node(mrb, masgn_node(tree)->rest, offset+2);
      }
    }
    /* Handle post-splat variables */
    if (masgn_node(tree)->post) {
      dump_prefix(offset+1, lineno);
      printf("post:\n");
      dump_recur(mrb, masgn_node(tree)->post, offset+2);
    }
    if (masgn_node(tree)->rhs) {
      dump_prefix(offset+1, lineno);
      printf("rhs:\n");
      dump_node(mrb, masgn_node(tree)->rhs, offset+2);
    }
    break;

  case NODE_RETURN:
    printf("NODE_RETURN:\n");
    if (return_node(tree)->args) {
      dump_node(mrb, return_node(tree)->args, offset);
    }
    break;

  case NODE_BREAK:
    printf("NODE_BREAK:\n");
    if (break_node(tree)->value) {
      dump_prefix(offset+1, lineno);
      printf("value:\n");
      dump_node(mrb, break_node(tree)->value, offset+2);
    }
    break;

  case NODE_NEXT:
    printf("NODE_NEXT:\n");
    if (next_node(tree)->value) {
      dump_prefix(offset+1, lineno);
      printf("value:\n");
      dump_node(mrb, next_node(tree)->value, offset+2);
    }
    break;

  case NODE_NEGATE:
    printf("NODE_NEGATE:\n");
    if (negate_node(tree)->operand) {
      dump_prefix(offset+1, lineno);
      printf("operand:\n");
      dump_node(mrb, negate_node(tree)->operand, offset+2);
    }
    break;

  case NODE_STMTS:
    printf("NODE_STMTS:\n");
    if (stmts_node(tree)->stmts) {
      dump_recur(mrb, stmts_node(tree)->stmts, offset+1);
    }
    break;

  case NODE_BEGIN:
    printf("NODE_BEGIN:\n");
    if (begin_node(tree)->body) {
      dump_node(mrb, begin_node(tree)->body, offset+1);
    }
    break;

  case NODE_RESCUE:
    printf("NODE_RESCUE:\n");
    if (rescue_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, rescue_node(tree)->body, offset+2);
    }
    if (rescue_node(tree)->rescue_clauses) {
      node *n2 = rescue_node(tree)->rescue_clauses;
      dump_prefix(offset+1, lineno);
      printf("rescue:\n");
      while (n2) {
        node *n3 = n2->car;
        if (n3->car) {
          dump_prefix(offset+2, lineno);
          printf("handle classes:\n");
          dump_recur(mrb, n3->car, offset+3);
        }
        if (n3->cdr->car) {
          dump_prefix(offset+2, lineno);
          printf("exc_var:\n");
          dump_node(mrb, n3->cdr->car, offset+3);
        }
        if (n3->cdr->cdr->car) {
          dump_prefix(offset+2, lineno);
          printf("rescue body:\n");
          dump_node(mrb, n3->cdr->cdr->car, offset+3);
        }
        n2 = n2->cdr;
      }
    }
    if (rescue_node(tree)->else_clause) {
      dump_prefix(offset+1, lineno);
      printf("else:\n");
      dump_node(mrb, rescue_node(tree)->else_clause, offset+2);
    }
    break;

  case NODE_ENSURE:
    printf("NODE_ENSURE:\n");
    if (ensure_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, ensure_node(tree)->body, offset+2);
    }
    if (ensure_node(tree)->ensure_clause) {
      dump_prefix(offset+1, lineno);
      printf("ensure:\n");
      dump_node(mrb, ensure_node(tree)->ensure_clause, offset+2);
    }
    break;

  case NODE_LAMBDA:
    printf("NODE_LAMBDA:\n");
    goto block;

  case NODE_BLOCK:
    printf("NODE_BLOCK:\n");
  block:
    if (block_node(tree)->locals) {
      dump_locals(mrb, block_node(tree)->locals, offset+1, lineno);
    }
    if (block_node(tree)->args) {
      dump_args(mrb, block_node(tree)->args, offset+1, lineno);
    }
    dump_prefix(offset+1, lineno);
    printf("body:\n");
    dump_node(mrb, block_node(tree)->body, offset+2);
    break;

  case NODE_AND:
    printf("NODE_AND:\n");
    dump_node(mrb, and_node(tree)->left, offset+1);
    dump_node(mrb, and_node(tree)->right, offset+1);
    break;

  case NODE_OR:
    printf("NODE_OR:\n");
    dump_node(mrb, or_node(tree)->left, offset+1);
    dump_node(mrb, or_node(tree)->right, offset+1);
    break;

  case NODE_CASE:
    printf("NODE_CASE:\n");
    if (case_node(tree)->value) {
      dump_prefix(offset+1, lineno);
      printf("value:\n");
      dump_node(mrb, case_node(tree)->value, offset+2);
    }
    if (case_node(tree)->body) {
      node *when_node = case_node(tree)->body;
      while (when_node) {
        dump_prefix(offset+1, lineno);
        printf("when:\n");
        node *when_clause = when_node->car;
        if (when_clause && when_clause->car) {
          dump_prefix(offset+2, lineno);
          printf("cond:\n");
          dump_recur(mrb, when_clause->car, offset+3);
        }
        if (when_clause && when_clause->cdr) {
          dump_prefix(offset+2, lineno);
          printf("body:\n");
          dump_node(mrb, when_clause->cdr, offset+3);
        }
        when_node = when_node->cdr;
      }
    }
    break;

  case NODE_WHILE:
    printf("NODE_WHILE:\n");
    goto dump_loop_node;
  case NODE_UNTIL:
    printf("NODE_UNTIL:\n");
    goto dump_loop_node;
  case NODE_WHILE_MOD:
    printf("NODE_WHILE_MOD:\n");
    goto dump_loop_node;
  case NODE_UNTIL_MOD:
    printf("NODE_UNTIL_MOD:\n");

  dump_loop_node:
    dump_prefix(offset+1, lineno);
    printf("cond:\n");
    dump_node(mrb, while_node(tree)->condition, offset+2);
    dump_prefix(offset+1, lineno);
    printf("body:\n");
    dump_node(mrb, while_node(tree)->body, offset+2);
    break;

  case NODE_FOR:
    printf("NODE_FOR:\n");
    if (for_node(tree)->var) {
      dump_prefix(offset+1, lineno);
      printf("var:\n");
      /* FOR_NODE_VAR structure:
       * var_list->car: cons-list of pre-splat variables
       * var_list->cdr->car: splat varnode (not a cons-list)
       * var_list->cdr->cdr->car: cons-list of post-splat variables */
      node *var_list = for_node(tree)->var;
      if (var_list) {
        dump_recur(mrb, var_list->car, offset+2);
        if (var_list && var_list->cdr) {
          /* Second element is a varnode, not a cons-list */
          dump_prefix(offset+1, lineno);
          printf("splat var:\n");
          dump_node(mrb, var_list->cdr->car, offset+2);
          if (var_list->cdr->cdr) {
           /* Third element is a cons-list of post-splat variables */
           dump_prefix(offset+1, lineno);
           printf("post var:\n");
           dump_recur(mrb, var_list->cdr->cdr->car, offset+2);
          }
        }
      }
    }
    if (for_node(tree)->iterable) {
      dump_prefix(offset+1, lineno);
      printf("iterable:\n");
      dump_node(mrb, for_node(tree)->iterable, offset+2);
    }
    if (for_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, for_node(tree)->body, offset+2);
    }
    break;

  case NODE_DOT2:
    printf("NODE_DOT2:\n");
    {
      if (dot2_node(tree)->left) {
        dump_prefix(offset+1, lineno);
        printf("left:\n");
        dump_node(mrb, dot2_node(tree)->left, offset+2);
      }
      if (dot2_node(tree)->right) {
        dump_prefix(offset+1, lineno);
        printf("right:\n");
        dump_node(mrb, dot2_node(tree)->right, offset+2);
      }
    }
    break;

  case NODE_DOT3:
    printf("NODE_DOT3:\n");
    {
      if (dot3_node(tree)->left) {
        dump_prefix(offset+1, lineno);
        printf("left:\n");
        dump_node(mrb, dot3_node(tree)->left, offset+2);
      }
      if (dot3_node(tree)->right) {
        dump_prefix(offset+1, lineno);
        printf("right:\n");
        dump_node(mrb, dot3_node(tree)->right, offset+2);
      }
    }
    break;

  case NODE_COLON2:
    printf("NODE_COLON2:\n");
    if (colon2_node(tree)->base) {
      dump_prefix(offset+1, lineno);
      printf("base:\n");
      dump_node(mrb, colon2_node(tree)->base, offset+2);
    }
    dump_prefix(offset+1, lineno);
    printf("name: %s\n", mrb_sym_name(mrb, colon2_node(tree)->name));
    break;

  case NODE_COLON3:
    printf("NODE_COLON3: ::%s\n", mrb_sym_name(mrb, colon3_node(tree)->name));
    break;

  case NODE_HASH:
    printf("NODE_HASH:\n");
    {
      node *pairs = hash_node(tree)->pairs;
      while (pairs) {
        dump_prefix(offset+1, lineno);
        printf("key:\n");
        if (node_to_sym(pairs->car->car) == MRB_OPSYM(pow)) {
          dump_prefix(offset+2, lineno);
          printf("**\n");
        }
        else {
          dump_node(mrb, pairs->car->car, offset+2);
        }
        dump_prefix(offset+1, lineno);
        printf("value:\n");
        dump_node(mrb, pairs->car->cdr, offset+2);
        pairs = pairs->cdr;
      }
    }
    break;

  case NODE_SPLAT:
    printf("NODE_SPLAT:\n");
    dump_node(mrb, splat_node(tree)->value, offset+1);
    break;

  case NODE_OP_ASGN:
    printf("NODE_OP_ASGN:\n");
    dump_prefix(offset+1, lineno);
    printf("lhs:\n");
    dump_node(mrb, op_asgn_node(tree)->lhs, offset+2);
    dump_prefix(offset+1, lineno);
    printf("op='%s' (%d)\n", mrb_sym_name(mrb, op_asgn_node(tree)->op), (int)op_asgn_node(tree)->op);
    dump_node(mrb, op_asgn_node(tree)->rhs, offset+1);
    break;

  case NODE_SUPER:
    printf("NODE_SUPER:\n");
    if (super_node(tree)->args) {
      dump_callargs(mrb, super_node(tree)->args, offset, lineno);
    }
    break;

  case NODE_ZSUPER:
    printf("NODE_ZSUPER:\n");
    if (super_node(tree)->args) {
      dump_callargs(mrb, super_node(tree)->args, offset, lineno);
    }
    break;

  case NODE_YIELD:
    printf("NODE_YIELD:\n");
    if (yield_node(tree)->args) {
      dump_callargs(mrb, yield_node(tree)->args, offset, lineno);
    }
    break;

  case NODE_REDO:
    printf("NODE_REDO\n");
    break;

  case NODE_RETRY:
    printf("NODE_RETRY\n");
    break;

  case NODE_BACK_REF:
    printf("NODE_BACK_REF: $%c\n", node_to_int(tree));
    break;

  case NODE_NTH_REF:
    printf("NODE_NTH_REF: $%d\n", node_to_int(tree));
    break;

  case NODE_BLOCK_ARG:
    printf("NODE_BLOCK_ARG:\n");
    dump_node(mrb, block_arg_node(tree)->value, offset+1);
    break;

  case NODE_REGX:
    printf("NODE_REGX:\n");
    if (regx_node(tree)->list) {
      dump_str(mrb, regx_node(tree)->list, offset+1, lineno);
    }
    if (regx_node(tree)->flags) {
      dump_prefix(offset+1, lineno);
      printf("flags: %s\n", regx_node(tree)->flags);
    }
    if (regx_node(tree)->encoding) {
      dump_prefix(offset+1, lineno);
      printf("encoding: %s\n", regx_node(tree)->encoding);
    }
    break;

  case NODE_WORDS:
    printf("NODE_WORDS:\n");
    if (words_node(tree)->args) {
      node *list = words_node(tree)->args;
      while (list && list->car) {
        node *item = list->car;
        if (item->car == 0 && item->cdr == 0) {
          /* Skip separator (0 . 0) */
        }
        else if (item->car && item->cdr) {
          /* String item: (len . str) */
          dump_prefix(offset+1, lineno);
          int len = node_to_int(item->car);
          if (len >= 0 && len < 1000 && item->cdr) {
            printf("word: \"%.*s\"\n", len, (char*)item->cdr);
          }
        }
        list = list->cdr;
      }
    }
    break;

  case NODE_SYMBOLS:
    printf("NODE_SYMBOLS:\n");
    if (symbols_node(tree)->args) {
      node *list = symbols_node(tree)->args;
      while (list && list->car) {
        node *item = list->car;
        if (item->car == 0 && item->cdr == 0) {
          /* Skip separator (0 . 0) */
        }
        else if (item->car && item->cdr) {
          /* String item: (len . str) */
          dump_prefix(offset+1, lineno);
          int len = node_to_int(item->car);
          if (len >= 0 && len < 1000 && item->cdr) {
            printf("symbol: \"%.*s\"\n", len, (char*)item->cdr);
          }
        }
        list = list->cdr;
      }
    }
    break;

  case NODE_ALIAS:
    printf("NODE_ALIAS %s %s:\n",
           mrb_sym_dump(mrb, node_to_sym(tree->car)),
           mrb_sym_dump(mrb, node_to_sym(tree->cdr)));
    break;

  case NODE_UNDEF:
    printf("NODE_UNDEF");
    {
      node *t = tree;
      while (t) {
        printf(" %s", mrb_sym_dump(mrb, node_to_sym(t->car)));
        t = t->cdr;
      }
    }
    printf(":\n");
    break;

  case NODE_CLASS:
    printf("NODE_CLASS:\n");
    if (class_node(tree)->name) {
      dump_cpath(mrb, module_node(tree)->name, offset+1, lineno);
    }
    if (class_node(tree)->superclass) {
      dump_prefix(offset+1, lineno);
      printf("super:\n");
      dump_node(mrb, class_node(tree)->superclass, offset+2);
    }
    if (class_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, class_node(tree)->body->cdr, offset+2);
    }
    break;

  case NODE_MODULE:
    printf("NODE_MODULE:\n");
    if (module_node(tree)->name) {
      dump_cpath(mrb, module_node(tree)->name, offset+1, lineno);
    }
    if (module_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, module_node(tree)->body->cdr, offset+2);
    }
    break;

  case NODE_SCLASS:
    printf("NODE_SCLASS:\n");
    if (sclass_node(tree)->obj) {
      dump_prefix(offset+1, lineno);
      printf("obj:\n");
      dump_node(mrb, sclass_node(tree)->obj, offset+2);
    }
    if (sclass_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, sclass_node(tree)->body->cdr, offset+2);
    }
    break;

  case NODE_SDEF:
    printf("NODE_SDEF: %s\n", mrb_sym_dump(mrb, def_node(tree)->name));
    if (sdef_node(tree)->obj) {
      dump_prefix(offset+1, lineno);
      printf("recv:\n");
      dump_node(mrb, sdef_node(tree)->obj, offset+2);
    }
    if (sdef_node(tree)->args) {
      dump_args(mrb, sdef_node(tree)->args, offset+1, lineno);
    }
    if (sdef_node(tree)->locals) {
      dump_locals(mrb, sdef_node(tree)->locals, offset+1, lineno);
    }
    if (sdef_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, sdef_node(tree)->body, offset+2);
    }
    break;

  case NODE_POSTEXE:
    printf("NODE_POSTEXE:\n");
    dump_node(mrb, tree, offset+1);
    break;

  case NODE_HEREDOC:
    printf("NODE_HEREDOC:\n");
    if (heredoc_node(tree)->info.term) {
      dump_prefix(offset+1, lineno);
      printf("terminator: \"%s\"\n", heredoc_node(tree)->info.term);
    }
    if (heredoc_node(tree)->info.doc) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_str(mrb, heredoc_node(tree)->info.doc, offset+2, lineno);
    }
    if (heredoc_node(tree)->info.allow_indent) {
      dump_prefix(offset+1, lineno);
      printf("allow_indent: true\n");
    }
    if (heredoc_node(tree)->info.remove_indent) {
      dump_prefix(offset+1, lineno);
      printf("remove_indent: true\n");
    }
    break;

  case NODE_CASE_MATCH:
    printf("NODE_CASE_MATCH:\n");
    if (case_match_node(tree)->value) {
      dump_prefix(offset+1, lineno);
      printf("value:\n");
      dump_node(mrb, case_match_node(tree)->value, offset+2);
    }
    if (case_match_node(tree)->in_clauses) {
      node *in_clause = case_match_node(tree)->in_clauses;
      while (in_clause) {
        dump_node(mrb, in_clause->car, offset+1);
        in_clause = in_clause->cdr;
      }
    }
    break;

  case NODE_IN:
    printf("NODE_IN:\n");
    if (in_node(tree)->pattern) {
      dump_prefix(offset+1, lineno);
      printf("pattern:\n");
      dump_node(mrb, in_node(tree)->pattern, offset+2);
    }
    if (in_node(tree)->guard) {
      dump_prefix(offset+1, lineno);
      printf("guard (%s):\n", in_node(tree)->guard_is_unless ? "unless" : "if");
      dump_node(mrb, in_node(tree)->guard, offset+2);
    }
    if (in_node(tree)->body) {
      dump_prefix(offset+1, lineno);
      printf("body:\n");
      dump_node(mrb, in_node(tree)->body, offset+2);
    }
    break;

  case NODE_PAT_VALUE:
    printf("NODE_PAT_VALUE:\n");
    if (pat_value_node(tree)->value) {
      dump_node(mrb, pat_value_node(tree)->value, offset+1);
    }
    break;

  case NODE_PAT_VAR:
    if (pat_var_node(tree)->name) {
      printf("NODE_PAT_VAR: %s\n", mrb_sym_dump(mrb, pat_var_node(tree)->name));
    }
    else {
      printf("NODE_PAT_VAR: _ (wildcard)\n");
    }
    break;

  case NODE_PAT_PIN:
    printf("NODE_PAT_PIN: ^%s\n", mrb_sym_dump(mrb, pat_pin_node(tree)->name));
    break;

  case NODE_PAT_AS:
    printf("NODE_PAT_AS: => %s\n", mrb_sym_dump(mrb, pat_as_node(tree)->name));
    if (pat_as_node(tree)->pattern) {
      dump_prefix(offset+1, lineno);
      printf("pattern:\n");
      dump_node(mrb, pat_as_node(tree)->pattern, offset+2);
    }
    break;

  case NODE_PAT_ALT:
    printf("NODE_PAT_ALT:\n");
    if (pat_alt_node(tree)->left) {
      dump_prefix(offset+1, lineno);
      printf("left:\n");
      dump_node(mrb, pat_alt_node(tree)->left, offset+2);
    }
    if (pat_alt_node(tree)->right) {
      dump_prefix(offset+1, lineno);
      printf("right:\n");
      dump_node(mrb, pat_alt_node(tree)->right, offset+2);
    }
    break;

  case NODE_PAT_ARRAY:
    printf("NODE_PAT_ARRAY:\n");
    if (pat_array_node(tree)->pre) {
      dump_prefix(offset+1, lineno);
      printf("pre:\n");
      dump_recur(mrb, pat_array_node(tree)->pre, offset+2);
    }
    if (pat_array_node(tree)->rest) {
      dump_prefix(offset+1, lineno);
      if (pat_array_node(tree)->rest == (node*)-1) {
        printf("rest: * (anonymous)\n");
      }
      else {
        printf("rest:\n");
        dump_node(mrb, pat_array_node(tree)->rest, offset+2);
      }
    }
    if (pat_array_node(tree)->post) {
      dump_prefix(offset+1, lineno);
      printf("post:\n");
      dump_recur(mrb, pat_array_node(tree)->post, offset+2);
    }
    break;

  case NODE_PAT_HASH:
    printf("NODE_PAT_HASH:\n");
    if (pat_hash_node(tree)->pairs) {
      dump_prefix(offset+1, lineno);
      printf("pairs:\n");
      dump_recur(mrb, pat_hash_node(tree)->pairs, offset+2);
    }
    if (pat_hash_node(tree)->rest) {
      dump_prefix(offset+1, lineno);
      if (pat_hash_node(tree)->rest == (node*)-1) {
        printf("rest: **nil\n");
      }
      else {
        printf("rest:\n");
        dump_node(mrb, pat_hash_node(tree)->rest, offset+2);
      }
    }
    break;

  case NODE_MATCH_PAT:
    printf("NODE_MATCH_PAT%s:\n", match_pat_node(tree)->raise_on_fail ? " (=>)" : " (in)");
    dump_prefix(offset+1, lineno);
    printf("value:\n");
    dump_node(mrb, match_pat_node(tree)->value, offset+2);
    dump_prefix(offset+1, lineno);
    printf("pattern:\n");
    dump_node(mrb, match_pat_node(tree)->pattern, offset+2);
    break;

  default:
    /* Fallback: unknown node type - skip like codegen.c does */
    printf("unknown node type %d (0x%x)\n", nodetype, (unsigned)nodetype);
    break;
  }
#endif
}

void
mrb_parser_dump(mrb_state *mrb, node *tree, int offset)
{
  dump_node(mrb, tree, offset);
}

typedef mrb_bool mrb_parser_foreach_top_variable_func(mrb_state *mrb, mrb_sym sym, void *user);
void mrb_parser_foreach_top_variable(mrb_state *mrb, struct mrb_parser_state *p, mrb_parser_foreach_top_variable_func *func, void *user);

void
mrb_parser_foreach_top_variable(mrb_state *mrb, struct mrb_parser_state *p, mrb_parser_foreach_top_variable_func *func, void *user)
{
  const mrb_ast_node *n = p->tree;
  if (node_type_p((node*)n, NODE_SCOPE)) {
    /* Extract locals from variable-sized NODE_SCOPE */
    struct mrb_ast_scope_node *scope = scope_node(n);
    n = scope->locals;
    for (; n; n = n->cdr) {
      mrb_sym sym = node_to_sym(n->car);
      if (sym != 0) {
        if (!func(mrb, sym, user)) break;
      }
    }
  }
}
