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Copy pathparser.rs
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2019 lines (1897 loc) · 95.1 KB
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use crate::ast::*;
use crate::error::{ParseError, ParseErrorKind, ErrorReporter};
use crate::lexer::{Token, TokenKind};
use crate::span::Span;
pub struct Parser {
tokens: Vec<Token>,
pos: usize,
#[allow(dead_code)] source: String,
file: String,
pub errors: ErrorReporter,
}
#[allow(dead_code)]
impl Parser {
pub fn new(tokens: Vec<Token>, source: String, file: String) -> Self {
Self { tokens, pos: 0, source, file, errors: ErrorReporter::new() }
}
// ── Token navigation ──────────────────────────────────────────────────────
fn current(&self) -> &Token {
self.tokens.get(self.pos).unwrap_or_else(|| self.tokens.last().unwrap())
}
fn peek_at(&self, offset: usize) -> &Token {
self.tokens.get(self.pos + offset).unwrap_or_else(|| self.tokens.last().unwrap())
}
fn advance(&mut self) -> &Token {
let t = &self.tokens[self.pos];
if self.pos < self.tokens.len() - 1 { self.pos += 1; }
t
}
fn skip_newlines(&mut self) {
while matches!(self.current().kind, TokenKind::Newline) { self.advance(); }
}
fn at(&self, kind: &TokenKind) -> bool {
std::mem::discriminant(&self.current().kind) == std::mem::discriminant(kind)
}
fn expect(&mut self, kind: &TokenKind) -> Result<Token, ParseError> {
if std::mem::discriminant(&self.current().kind) == std::mem::discriminant(kind) {
Ok(self.advance().clone())
} else {
Err(ParseError::new(
ParseErrorKind::ExpectedToken(format!("{:?}", kind)),
self.current().span.clone(),
format!("expected `{}`, found `{}`", token_kind_name(kind), self.current().text),
vec![format!("add `{}` here", token_kind_name(kind))],
))
}
}
fn expect_ident(&mut self) -> Result<(String, Span), ParseError> {
if let TokenKind::Ident(name) = &self.current().kind {
let name = name.clone();
let span = self.current().span.clone();
self.advance();
Ok((name, span))
} else {
Err(ParseError::new(
ParseErrorKind::ExpectedIdent,
self.current().span.clone(),
format!("expected identifier, found `{}`", self.current().text),
vec!["provide a valid identifier here".to_string()],
))
}
}
/// Like `expect_ident`, but also accepts a fixed set of "soft" keywords
/// that are reserved words in statement/type position but are extremely
/// common as method or path-segment names in real-world APIs — most
/// importantly `new` (`Type::new()`) and `write` (`module::write()`).
/// Without this, `col::HashMap::new()` or `fs::write(...)` fail to
/// parse with a confusing "expected identifier, found `new`" error,
/// even though `new`/`write` are perfectly unambiguous in path-segment
/// position (they can never start a path segment themselves, so there's
/// no grammar conflict in allowing them here).
fn expect_path_segment(&mut self) -> Result<(String, Span), ParseError> {
let span = self.current().span.clone();
let text = match &self.current().kind {
TokenKind::Ident(name) => Some(name.clone()),
TokenKind::New => Some("new".to_string()),
TokenKind::Write => Some("write".to_string()),
TokenKind::Type => Some("type".to_string()),
TokenKind::End => Some("end".to_string()),
TokenKind::As => Some("as".to_string()),
TokenKind::Is => Some("is".to_string()),
TokenKind::From => Some("from".to_string()),
TokenKind::Use => Some("use".to_string()),
TokenKind::Match => Some("match".to_string()),
TokenKind::In => Some("in".to_string()),
TokenKind::For => Some("for".to_string()),
TokenKind::Mod => Some("mod".to_string()),
TokenKind::Async => Some("async".to_string()),
TokenKind::Await => Some("await".to_string()),
TokenKind::Self_ => Some("self".to_string()),
_ => None,
};
match text {
Some(name) => { self.advance(); Ok((name, span)) }
None => Err(ParseError::new(
ParseErrorKind::ExpectedIdent,
span,
format!("expected identifier, found `{}`", self.current().text),
vec!["provide a valid identifier here".to_string()],
)),
}
}
fn error(&self, msg: impl Into<String>, hints: Vec<String>) -> ParseError {
let msg_str: String = msg.into();
ParseError::new(
ParseErrorKind::Custom(msg_str.clone()),
self.current().span.clone(),
msg_str,
hints,
)
}
fn recover(&mut self) {
// Always consume at least one token before checking the stop
// condition. Without this, an error that leaves the cursor sitting
// exactly on a stop-token (e.g. `Fn`) makes recover() a no-op —
// the caller's retry loop then sees the identical token again,
// fails the identical way, calls recover() again, and never makes
// progress. This was the root cause of a real hang (see the
// TokenKind::Fn case in parse_type_base for the original trigger);
// advancing unconditionally here makes recovery robust against
// this whole class of stuck-cursor bugs, not just the one trigger
// that's now also fixed at the source.
if !matches!(self.current().kind, TokenKind::EOF) {
self.advance();
}
while !matches!(self.current().kind,
TokenKind::EOF | TokenKind::Newline | TokenKind::Fn | TokenKind::Struct |
TokenKind::Enum | TokenKind::Impl | TokenKind::Pub | TokenKind::Use |
TokenKind::End)
{
self.advance();
}
}
// ── Module ─────────────────────────────────────────────────────────────────
pub fn parse_module(&mut self) -> Module {
let mut directives = Vec::new();
let mut items = Vec::new();
let mut imports = Vec::new();
let mut edition: Option<String> = None;
self.skip_newlines();
while !matches!(self.current().kind, TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::EOF) { break; }
// `using "2026"` edition declaration
if matches!(self.current().kind, TokenKind::Using) {
self.advance();
if let TokenKind::StringLit(ed) = &self.current().kind.clone() {
edition = Some(ed.clone());
self.advance();
}
self.skip_newlines();
continue;
}
// Directives ~ / ~~
if let TokenKind::Directive(s) = &self.current().kind.clone() {
let span = self.current().span.clone(); let s = s.clone(); self.advance();
directives.push(Directive { kind: DirectiveKind::Dynamic, value: s, span });
continue;
}
if let TokenKind::FastDirective(s) = &self.current().kind.clone() {
let span = self.current().span.clone(); let s = s.clone(); self.advance();
directives.push(Directive { kind: DirectiveKind::Fast, value: s, span });
continue;
}
// `use` imports
if matches!(self.current().kind, TokenKind::Use) {
match self.parse_import() {
Ok((kind, alias, span)) => imports.push((kind, alias, span)),
Err(e) => { self.errors.report(e); self.recover(); }
}
continue;
}
// Top-level items
match self.parse_item() {
Ok(item) => items.push(item),
Err(e) => { self.errors.report(e); self.recover(); }
}
}
Module { file: self.file.clone(), edition, directives, items, imports }
}
// ── Import ────────────────────────────────────────────────────────────────
fn parse_import(&mut self) -> Result<(ImportKind, Option<String>, Span), ParseError> {
let start = self.current().span.clone();
self.advance(); // consume 'use'
let path_tok = if let TokenKind::StringLit(s) = &self.current().kind.clone() {
let s = s.clone(); self.advance(); s
} else {
return Err(self.error("expected use path string after `use`",
vec![r#"write: use "std -> io" from "io""#.to_string()]));
};
let alias = if matches!(self.current().kind, TokenKind::From) {
self.advance();
if let TokenKind::StringLit(a) = &self.current().kind.clone() {
let a = a.clone(); self.advance(); Some(a)
} else {
return Err(self.error("expected alias string after `from`", vec![]));
}
} else { None };
let span = start.merge(&self.current().span);
let kind = parse_use_path(&path_tok, alias.clone())
.ok_or_else(|| ParseError::new(
ParseErrorKind::Custom("invalid use path".into()),
span.clone(),
format!("cannot parse use path `{}`", path_tok),
vec![r#"valid forms: "std -> module", "vira -> pkg/1.0""#.to_string()],
))?;
Ok((kind, alias, span))
}
// ── Attributes ────────────────────────────────────────────────────────────
fn parse_attributes(&mut self) -> Vec<Attribute> {
let mut attrs = Vec::new();
while matches!(self.current().kind, TokenKind::Hash) {
let span = self.current().span.clone();
self.advance(); // #
if !matches!(self.current().kind, TokenKind::LBracket) { break; }
self.advance(); // [
let (name, _) = self.expect_ident().unwrap_or_else(|_| (String::new(), self.current().span.clone()));
let mut args = Vec::new();
if matches!(self.current().kind, TokenKind::LParen) {
self.advance(); // (
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
let (k, _) = self.expect_ident().unwrap_or_else(|_| (String::new(), self.current().span.clone()));
if matches!(self.current().kind, TokenKind::Assign) {
self.advance();
let v = if let TokenKind::StringLit(s) = &self.current().kind.clone() {
let s = s.clone(); self.advance(); s
} else { String::new() };
args.push(AttrArg::KeyValue(k, v));
} else {
args.push(AttrArg::Ident(k));
}
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
if matches!(self.current().kind, TokenKind::RParen) { self.advance(); }
}
if matches!(self.current().kind, TokenKind::RBracket) { self.advance(); }
let end_span = self.current().span.clone();
attrs.push(Attribute { name, args, span: span.merge(&end_span) });
self.skip_newlines();
}
attrs
}
// ── Items ─────────────────────────────────────────────────────────────────
fn parse_item(&mut self) -> Result<Item, ParseError> {
self.skip_newlines();
let attrs = self.parse_attributes();
let pub_ = if matches!(self.current().kind, TokenKind::Pub) {
self.advance(); true
} else { false };
match &self.current().kind {
TokenKind::Fn => self.parse_fn_with_attrs(pub_, attrs).map(Item::FnDef),
TokenKind::Struct => self.parse_struct(pub_).map(Item::StructDef),
TokenKind::Enum => self.parse_enum(pub_).map(Item::EnumDef),
TokenKind::Trait => self.parse_trait(pub_).map(Item::TraitDef),
TokenKind::Impl => self.parse_impl().map(Item::ImplBlock),
TokenKind::Type => self.parse_type_alias(pub_),
TokenKind::Async => {
self.advance();
let fn_def = self.parse_fn_with_attrs(pub_, attrs)?;
Ok(Item::FnDef(FnDef { is_async: true, ..fn_def }))
}
TokenKind::Mod => self.parse_mod_decl(pub_),
TokenKind::Extern => self.parse_extern_block_inline(),
TokenKind::Using => {
self.advance();
if let TokenKind::StringLit(_) = &self.current().kind.clone() { self.advance(); }
self.skip_newlines();
self.parse_item()
}
_ => Err(self.error(
format!("unexpected token `{}` at top level", self.current().text),
vec!["expected fn, struct, enum, trait, impl, type, mod, or extern".to_string()],
)),
}
}
fn parse_mod_decl(&mut self, pub_: bool) -> Result<Item, ParseError> {
let span = self.current().span.clone();
self.advance(); // mod
let (name, _) = self.expect_ident()?;
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
let mut inner = Vec::new();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End | TokenKind::EOF) { break; }
match self.parse_item() {
Ok(i) => inner.push(i),
Err(e) => { self.errors.report(e); self.recover(); }
}
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
let end = self.current().span.clone();
Ok(Item::ModDecl { name, pub_, inline: Some(inner), span: span.merge(&end) })
} else {
let end = self.current().span.clone();
Ok(Item::ModDecl { name, pub_, inline: None, span: span.merge(&end) })
}
}
fn parse_fn(&mut self, pub_: bool) -> Result<FnDef, ParseError> {
self.parse_fn_with_attrs(pub_, vec![])
}
fn parse_fn_with_attrs(&mut self, pub_: bool, attrs: Vec<Attribute>) -> Result<FnDef, ParseError> {
let start = self.current().span.clone();
self.advance(); // fn
let is_async = if matches!(self.current().kind, TokenKind::Async) { self.advance(); true } else { false };
let is_unsafe = if matches!(self.current().kind, TokenKind::Unsafe) { self.advance(); true } else { false };
// Use expect_path_segment (not expect_ident) here: `new` and `write`
// are reserved keyword tokens but are also extremely common
// function/method names (`fn new(...)`, constructor-style; `fn
// write(...)`, e.g. inside `impl Buffer`). They're unambiguous in
// this position — nothing else can follow `fn` here — so accepting
// them avoids a confusing "expected identifier, found `new`" error
// on otherwise completely ordinary code (see tests/core/types_test.h#'s
// `impl Point is fn new(x, y) -> Point ... end end`).
let (name, _) = self.expect_path_segment()?;
let type_params = self.parse_generics_decl()?;
self.expect(&TokenKind::LParen)?;
let params = self.parse_params()?;
self.expect(&TokenKind::RParen)?;
let return_type = if matches!(self.current().kind, TokenKind::Arrow) {
self.advance(); Some(self.parse_type()?)
} else { None };
self.skip_newlines();
let body = self.parse_block()?;
let span = start.merge(&self.current().span);
Ok(FnDef { attrs, type_params, name, params, return_type, body, pub_, is_async, is_unsafe, span })
}
fn parse_params(&mut self) -> Result<Vec<Param>, ParseError> {
let mut params = Vec::new();
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::RParen) { break; }
let span = self.current().span.clone();
let mutable = if matches!(self.current().kind, TokenKind::Mut) { self.advance(); true } else { false };
if matches!(self.current().kind, TokenKind::Self_) {
let s = self.advance().span.clone();
params.push(Param { name: "self".to_string(), ty: TypeExpr::Named("Self".to_string()), mutable, span: s });
} else {
let (name, _) = self.expect_ident()?;
self.expect(&TokenKind::Colon)?;
let ty = self.parse_type()?;
params.push(Param { name, ty, mutable, span });
}
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); } else { break; }
}
Ok(params)
}
fn parse_block(&mut self) -> Result<Vec<Stmt>, ParseError> {
self.skip_newlines();
let mut stmts = Vec::new();
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End | TokenKind::EOF) { break; }
match self.parse_stmt() {
Ok(s) => stmts.extend(s),
Err(e) => { self.errors.report(e); self.recover(); }
}
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
} else if matches!(self.current().kind, TokenKind::Assign) {
self.advance();
let expr = self.parse_expr(0)?;
let span = expr.span().clone();
stmts.push(Stmt::Return(Some(expr), span));
} else {
return Err(self.error(
"expected `is` to start a block body",
vec!["write `is` before the body and `end` after".to_string()],
));
}
Ok(stmts)
}
/// Parse an if-branch body — stops at else/elsif/end without consuming them
fn parse_if_body(&mut self) -> Result<Vec<Stmt>, ParseError> {
self.skip_newlines();
// Must start with `is`
if !matches!(self.current().kind, TokenKind::Is) {
return Err(self.error(
"expected `is` after condition",
vec!["write: if cond is ... end".to_string()],
));
}
self.advance(); // consume `is`
self.skip_newlines();
let mut stmts = Vec::new();
loop {
self.skip_newlines();
match self.current().kind {
TokenKind::End | TokenKind::EOF => break,
TokenKind::Else | TokenKind::Elsif => break,
_ => {}
}
match self.parse_stmt() {
Ok(s) => stmts.extend(s),
Err(e) => { self.errors.report(e); self.recover(); }
}
}
// Only consume `end` if there is no else/elsif following
if matches!(self.current().kind, TokenKind::End) {
self.advance();
}
Ok(stmts)
}
fn parse_struct(&mut self, pub_: bool) -> Result<StructDef, ParseError> {
let start = self.current().span.clone();
self.advance(); // struct
let (name, _) = self.expect_ident()?;
let type_params = self.parse_generics_decl()?;
self.skip_newlines();
let mut fields = Vec::new();
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End) { break; }
let fpub = if matches!(self.current().kind, TokenKind::Pub) { self.advance(); true } else { false };
let fspan = self.current().span.clone();
let (fname, _) = self.expect_ident()?;
self.expect(&TokenKind::Colon)?;
let fty = self.parse_type()?;
fields.push(StructField { name: fname, ty: fty, pub_: fpub, span: fspan });
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
}
let span = start.merge(&self.current().span);
Ok(StructDef { attrs: vec![], type_params, name, fields, pub_, span })
}
fn parse_enum(&mut self, pub_: bool) -> Result<EnumDef, ParseError> {
let start = self.current().span.clone();
self.advance(); // enum
let (name, _) = self.expect_ident()?;
let type_params = self.parse_generics_decl()?;
self.skip_newlines();
let mut variants = Vec::new();
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End) { break; }
let vspan = self.current().span.clone();
let (vname, _) = self.expect_ident()?;
let fields = if matches!(self.current().kind, TokenKind::LParen) {
self.advance();
let mut types = Vec::new();
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
types.push(self.parse_type()?);
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
self.expect(&TokenKind::RParen)?;
EnumVariantFields::Tuple(types)
} else if matches!(self.current().kind, TokenKind::Is) {
// Struct variant: Variant is field: T ... end
self.advance(); self.skip_newlines();
let mut sfields = Vec::new();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End) { break; }
let fpub = if matches!(self.current().kind, TokenKind::Pub) { self.advance(); true } else { false };
let fs = self.current().span.clone();
let (fn_, _) = self.expect_ident()?;
self.expect(&TokenKind::Colon)?;
let ft = self.parse_type()?;
sfields.push(StructField { name: fn_, ty: ft, pub_: fpub, span: fs });
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
EnumVariantFields::Struct(sfields)
} else {
EnumVariantFields::Unit
};
variants.push(EnumVariant { name: vname, fields, span: vspan });
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
}
let span = start.merge(&self.current().span);
Ok(EnumDef { attrs: vec![], type_params, name, variants, pub_, span })
}
fn parse_trait(&mut self, pub_: bool) -> Result<TraitDef, ParseError> {
let start = self.current().span.clone();
self.advance(); // trait
let (name, _) = self.expect_ident()?;
self.skip_newlines();
let mut methods = Vec::new();
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End) { break; }
if matches!(self.current().kind, TokenKind::Fn) {
self.advance();
let mspan = self.current().span.clone();
let (mname, _) = self.expect_ident()?;
self.expect(&TokenKind::LParen)?;
let params = self.parse_params()?;
self.expect(&TokenKind::RParen)?;
let ret = if matches!(self.current().kind, TokenKind::Arrow) {
self.advance(); Some(self.parse_type()?)
} else { None };
self.skip_newlines();
let default_body = if matches!(self.current().kind, TokenKind::Is) {
Some(self.parse_block()?)
} else { None };
methods.push(TraitMethod { name: mname, params, return_type: ret, default_body, span: mspan });
} else {
let e = self.error("expected `fn` in trait", vec![]);
self.errors.report(e); self.recover();
}
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
}
let span = start.merge(&self.current().span);
Ok(TraitDef { attrs: vec![], type_params: vec![], name, methods, pub_, span })
}
fn parse_impl(&mut self) -> Result<ImplBlock, ParseError> {
let start = self.current().span.clone();
self.advance(); // impl
let (type_name, _) = self.expect_ident()?;
let trait_name = if matches!(self.current().kind, TokenKind::Colon) {
self.advance(); let (t, _) = self.expect_ident()?; Some(t)
} else { None };
self.skip_newlines();
let mut methods = Vec::new();
if matches!(self.current().kind, TokenKind::Is) {
self.advance(); self.skip_newlines();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End) { break; }
let pub_ = if matches!(self.current().kind, TokenKind::Pub) { self.advance(); true } else { false };
if matches!(self.current().kind, TokenKind::Fn) {
match self.parse_fn(pub_) {
Ok(f) => methods.push(f),
Err(e) => { self.errors.report(e); self.recover(); }
}
} else {
let e = self.error("expected `fn` in impl block", vec![]);
self.errors.report(e); self.recover();
}
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
}
let span = start.merge(&self.current().span);
Ok(ImplBlock { type_name, trait_name, methods, span })
}
fn parse_type_alias(&mut self, pub_: bool) -> Result<Item, ParseError> {
let start = self.current().span.clone();
self.advance(); // type
let (name, _) = self.expect_ident()?;
self.expect(&TokenKind::Assign)?;
let ty = self.parse_type()?;
let span = start.merge(&self.current().span);
Ok(Item::TypeAlias { name, ty, pub_, span })
}
fn parse_extern_block_inline(&mut self) -> Result<Item, ParseError> {
let span = self.current().span.clone();
self.advance(); // extern
let link_kind = {
let kw = if let TokenKind::Ident(ref s) = self.current().kind { s.clone() } else { String::new() };
match kw.as_str() {
"static" => { self.advance(); ExternLinkKind::Static }
"dynamic" => { self.advance(); ExternLinkKind::Dynamic }
_ => ExternLinkKind::Static,
}
};
let mut lang = ExternLang::C;
let mut library = None;
if matches!(self.current().kind, TokenKind::LBracket) {
self.advance();
let s = if let TokenKind::Ident(ref ss) = self.current().kind { ss.clone() } else { String::new() };
lang = match s.as_str() {
"rust" | "Rust" => ExternLang::Rust,
"cpp" | "c++" => ExternLang::Cpp,
"python" | "py" => ExternLang::Python,
_ => ExternLang::C,
};
self.advance();
if matches!(self.current().kind, TokenKind::Comma) {
self.advance();
if let TokenKind::StringLit(s) = &self.current().kind.clone() { library = Some(s.clone()); self.advance(); }
}
if matches!(self.current().kind, TokenKind::RBracket) { self.advance(); }
}
self.skip_newlines();
if matches!(self.current().kind, TokenKind::Is) { self.advance(); }
self.skip_newlines();
let mut functions = Vec::new();
while !matches!(self.current().kind, TokenKind::End | TokenKind::EOF) {
self.skip_newlines();
if matches!(self.current().kind, TokenKind::End | TokenKind::EOF) { break; }
if matches!(self.current().kind, TokenKind::Fn) {
self.advance();
let fspan = self.current().span.clone();
let (name, _) = self.expect_ident()?;
self.expect(&TokenKind::LParen)?;
let mut params = Vec::new();
let mut variadic = false;
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
if matches!(self.current().kind, TokenKind::DotDot) { variadic = true; self.advance(); break; }
let (pname, _) = self.expect_ident()?;
self.expect(&TokenKind::Colon)?;
let ty = self.parse_type()?;
params.push(Param { name: pname, ty, mutable: false, span: fspan.clone() });
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
self.expect(&TokenKind::RParen)?;
let ret = if matches!(self.current().kind, TokenKind::Arrow) { self.advance(); Some(self.parse_type()?) } else { None };
functions.push(ExternFnDecl { name, params, return_type: ret, variadic, span: fspan });
}
self.skip_newlines();
}
self.expect(&TokenKind::End)?;
Ok(Item::Extern(ExternBlock { lang, link_kind, library, functions, span }))
}
fn parse_generics_decl(&mut self) -> Result<Vec<TypeParam>, ParseError> {
let mut params = Vec::new();
if matches!(self.current().kind, TokenKind::Lt) {
self.advance();
while !matches!(self.current().kind, TokenKind::Gt | TokenKind::EOF) {
let span = self.current().span.clone();
let (name, _) = self.expect_ident()?;
let mut bounds = Vec::new();
if matches!(self.current().kind, TokenKind::Colon) {
self.advance();
loop {
let (bound, _) = self.expect_ident()?;
bounds.push(bound);
if matches!(self.current().kind, TokenKind::Plus) { self.advance(); } else { break; }
}
}
params.push(TypeParam { name, bounds, span });
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
self.expect(&TokenKind::Gt)?;
}
Ok(params)
}
// ── Types ─────────────────────────────────────────────────────────────────
fn parse_type(&mut self) -> Result<TypeExpr, ParseError> {
let mut ty = self.parse_type_base()?;
if matches!(self.current().kind, TokenKind::Question) {
self.advance();
ty = TypeExpr::Optional(Box::new(ty));
}
Ok(ty)
}
fn parse_type_base(&mut self) -> Result<TypeExpr, ParseError> {
match &self.current().kind {
TokenKind::TInt => { self.advance(); Ok(TypeExpr::Named("int".into())) }
TokenKind::TUint => { self.advance(); Ok(TypeExpr::Named("uint".into())) }
TokenKind::TI8 => { self.advance(); Ok(TypeExpr::Named("i8".into())) }
TokenKind::TI16 => { self.advance(); Ok(TypeExpr::Named("i16".into())) }
TokenKind::TI32 => { self.advance(); Ok(TypeExpr::Named("i32".into())) }
TokenKind::TI64 => { self.advance(); Ok(TypeExpr::Named("i64".into())) }
TokenKind::TI128 => { self.advance(); Ok(TypeExpr::Named("i128".into())) }
TokenKind::TU8 => { self.advance(); Ok(TypeExpr::Named("u8".into())) }
TokenKind::TU16 => { self.advance(); Ok(TypeExpr::Named("u16".into())) }
TokenKind::TU32 => { self.advance(); Ok(TypeExpr::Named("u32".into())) }
TokenKind::TU64 => { self.advance(); Ok(TypeExpr::Named("u64".into())) }
TokenKind::TU128 => { self.advance(); Ok(TypeExpr::Named("u128".into())) }
TokenKind::TF32 => { self.advance(); Ok(TypeExpr::Named("f32".into())) }
TokenKind::TF64 => { self.advance(); Ok(TypeExpr::Named("f64".into())) }
TokenKind::TBool => { self.advance(); Ok(TypeExpr::Named("bool".into())) }
TokenKind::TString => { self.advance(); Ok(TypeExpr::Named("string".into())) }
TokenKind::TBytes => { self.advance(); Ok(TypeExpr::Named("bytes".into())) }
TokenKind::TVoid => { self.advance(); Ok(TypeExpr::Void) }
TokenKind::TAny => { self.advance(); Ok(TypeExpr::Named("any".into())) }
// Function type: fn(T1, T2, ...) -> R — used for higher-order
// function parameters/returns, e.g. `f: fn(int) -> int`.
// TypeExpr::Fn already existed in the AST but nothing produced
// it, so `fn(...)` as a type previously fell through to the
// catch-all error arm below — and worse, since `Fn` is also one
// of `recover()`'s stopping tokens, the parser would get stuck
// unable to make forward progress on recovery (it stops exactly
// on the `fn` it can't parse, recover() sees it's already on a
// stop-token and does nothing, and the outer item loop retries
// the same token forever). This was the root cause of the
// tests/core/functions_test.h# and types_test.h# hangs.
TokenKind::Fn => {
self.advance();
self.expect(&TokenKind::LParen)?;
let mut param_types = Vec::new();
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
param_types.push(self.parse_type()?);
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); } else { break; }
}
self.expect(&TokenKind::RParen)?;
let ret = if matches!(self.current().kind, TokenKind::Arrow) {
self.advance();
self.parse_type()?
} else {
TypeExpr::Void
};
Ok(TypeExpr::Fn(param_types, Box::new(ret)))
}
TokenKind::BitAnd => {
self.advance();
let mutable = if matches!(self.current().kind, TokenKind::Mut) { self.advance(); true } else { false };
let inner = self.parse_type()?;
Ok(if mutable { TypeExpr::RefMut(Box::new(inner)) } else { TypeExpr::Ref(Box::new(inner)) })
}
TokenKind::LBracket => {
self.advance();
let inner = self.parse_type()?;
self.expect(&TokenKind::RBracket)?;
Ok(TypeExpr::Array(Box::new(inner)))
}
TokenKind::LParen => {
self.advance();
let mut types = Vec::new();
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
types.push(self.parse_type()?);
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
self.expect(&TokenKind::RParen)?;
Ok(TypeExpr::Tuple(types))
}
TokenKind::Ident(name) => {
let name = name.clone(); self.advance();
if matches!(self.current().kind, TokenKind::Lt) {
self.advance();
let mut args = Vec::new();
while !matches!(self.current().kind, TokenKind::Gt | TokenKind::EOF) {
args.push(self.parse_type()?);
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); }
}
self.expect(&TokenKind::Gt)?;
Ok(TypeExpr::Generic(name, args))
} else {
Ok(TypeExpr::Named(name))
}
}
_ => Err(self.error(
format!("expected a type, found `{}`", self.current().text),
vec!["valid types: int, string, bool, f64, [T], T?, or a struct name".to_string()],
)),
}
}
// ── Statements ────────────────────────────────────────────────────────────
pub fn parse_stmt(&mut self) -> Result<Vec<Stmt>, ParseError> {
self.skip_newlines();
match &self.current().kind {
TokenKind::Let => self.parse_let(),
TokenKind::Return => {
let span = self.current().span.clone(); self.advance();
let expr = if !matches!(self.current().kind,
TokenKind::Newline | TokenKind::EOF | TokenKind::End |
TokenKind::Else | TokenKind::Elsif)
{ Some(self.parse_expr(0)?) } else { None };
Ok(vec![Stmt::Return(expr, span)])
}
TokenKind::Use => {
let (kind, alias, span) = self.parse_import()?;
Ok(vec![Stmt::Import(kind, alias, span)])
}
TokenKind::Break => {
let span = self.current().span.clone(); self.advance();
let val = if !matches!(self.current().kind,
TokenKind::Newline | TokenKind::EOF | TokenKind::End)
{ Some(self.parse_expr(0)?) } else { None };
Ok(vec![Stmt::Break(val, span)])
}
TokenKind::Continue => {
let span = self.current().span.clone(); self.advance();
Ok(vec![Stmt::Continue(span)])
}
TokenKind::Fn | TokenKind::Struct | TokenKind::Enum |
TokenKind::Trait | TokenKind::Impl | TokenKind::Type | TokenKind::Pub => {
let item = self.parse_item()?;
Ok(vec![Stmt::Item(item)])
}
_ => {
let expr = self.parse_expr(0)?;
let span = expr.span().clone();
Ok(vec![Stmt::Expr(expr, span)])
}
}
}
fn parse_let(&mut self) -> Result<Vec<Stmt>, ParseError> {
let start = self.current().span.clone(); self.advance(); // let
let mutable = if matches!(self.current().kind, TokenKind::Mut) { self.advance(); true } else { false };
// Tuple destructuring: let (a, b) = expr / let mut (a, b) = expr
// Desugars to a hidden temp binding plus one Stmt::Let per name,
// each initialized via a tuple-field FieldAccess on the temp
// (`.0`, `.1`, ...) — reuses existing, already-supported AST nodes
// instead of introducing a new Stmt variant, which would require
// updating several exhaustive `match stmt` sites in the compiler
// crate (LLVM-dependent, not compile-verifiable in this sandbox).
if matches!(self.current().kind, TokenKind::LParen) {
self.advance();
let mut names = Vec::new();
while !matches!(self.current().kind, TokenKind::RParen | TokenKind::EOF) {
let (n, _) = self.expect_ident()?;
names.push(n);
if matches!(self.current().kind, TokenKind::Comma) { self.advance(); } else { break; }
}
self.expect(&TokenKind::RParen)?;
self.expect(&TokenKind::Assign)?;
let value = self.parse_expr(0)?;
let span = start.merge(&self.current().span);
let tmp_name = format!("__destructure_{}_{}", span.start.line, span.start.offset);
let mut out = vec![Stmt::Let {
name: tmp_name.clone(), ty: None, mutable: false,
value: Some(value), span: span.clone(),
}];
for (idx, n) in names.into_iter().enumerate() {
let field_access = Expr::FieldAccess(
Box::new(Expr::Ident(tmp_name.clone(), span.clone())),
idx.to_string(),
span.clone(),
);
out.push(Stmt::Let {
name: n, ty: None, mutable,
value: Some(field_access), span: span.clone(),
});
}
return Ok(out);
}
let (name, _) = self.expect_ident()?;
let ty = if matches!(self.current().kind, TokenKind::Colon) {
self.advance(); Some(self.parse_type()?)
} else { None };
let value = if matches!(self.current().kind, TokenKind::Assign) {
self.advance(); Some(self.parse_expr(0)?)
} else { None };
let span = start.merge(&self.current().span);
Ok(vec![Stmt::Let { name, ty, mutable, value, span }])
}
// ── Expressions ────────────────────────────────────────────────────────────
fn parse_expr(&mut self, min_bp: u8) -> Result<Expr, ParseError> {
let mut lhs = self.parse_prefix()?;
loop {
// NOTE: do NOT skip_newlines() here. If the current token is
// Newline, the expression ends at end-of-line (statement
// boundary) — break immediately without consuming it, so the
// outer statement loop can see it.
//
// Multi-line continuation (operator at END of line, e.g.
// `"a" +\n"b"`) is handled differently: the operator token is
// consumed BEFORE we reach a Newline, and parse_prefix() (called
// for the rhs) skips the following newline itself.
if matches!(self.current().kind,
TokenKind::EOF | TokenKind::End | TokenKind::Newline |
TokenKind::Comma | TokenKind::RParen | TokenKind::RBracket |
TokenKind::RBrace | TokenKind::Semicolon)
{
// SPECIAL CASE: method-chain continuation.
// result.trim()
// .to_lower()
// .replace("a", "b")
// Here `.to_lower()` starts the next line — the *leading*
// token is `.`. This is the one case where a leading
// operator on the next line is unambiguous: no valid H#
// expression ends with a bare value immediately followed
// by a statement that starts with `.` (field/method access
// on a fresh value with no receiver isn't valid syntax).
// So: if the current token is Newline, peek past all
// consecutive newlines; if the first real token is `.`,
// skip the newlines and continue the chain instead of
// ending the expression here.
if matches!(self.current().kind, TokenKind::Newline) {
let mut peek = self.pos;
while matches!(self.tokens.get(peek).map(|t| &t.kind), Some(TokenKind::Newline)) {
peek += 1;
}
if matches!(self.tokens.get(peek).map(|t| &t.kind), Some(TokenKind::Dot)) {
self.skip_newlines();
// fall through to infix handling below (current is now `.`)
} else {
break;
}
} else {
break;
}
}
let (l_bp, r_bp) = match infix_bp(&self.current().kind) {
Some(bp) => bp,
None => break,
};
if l_bp < min_bp { break; }
let op_tok = self.advance().clone();
let span = lhs.span().merge(&op_tok.span);
// Assignment
if matches!(op_tok.kind, TokenKind::Assign) {
let rhs = self.parse_expr(r_bp)?;
let s = lhs.span().merge(rhs.span());
lhs = Expr::Assign(Box::new(lhs), Box::new(rhs), s);
continue;
}
// Compound assignment
if let Some(op) = compound_op(&op_tok.kind) {
let rhs = self.parse_expr(r_bp)?;
let s = lhs.span().merge(rhs.span());
lhs = Expr::CompoundAssign(Box::new(lhs), op, Box::new(rhs), s);
continue;
}
// Method call / field access
if matches!(op_tok.kind, TokenKind::Dot) {
// Tuple field access: t.0, t.1, ... — the lexer tokenizes
// a bare integer here (not an identifier), so handle it
// before falling through to the identifier-based path used
// for struct field access and method calls.
if let TokenKind::Integer(n) = self.current().kind {
let idx_span = self.current().span.clone();
self.advance();
let s = lhs.span().merge(&idx_span);
lhs = Expr::FieldAccess(Box::new(lhs), n.to_string(), s);
continue;
}
let (name, _) = self.expect_ident()?;
if matches!(self.current().kind, TokenKind::LParen) {
self.advance();
let args = self.parse_call_args()?;
let s = lhs.span().merge(&self.current().span);
lhs = Expr::MethodCall(Box::new(lhs), name, args, s);
} else {
let s = lhs.span().merge(&self.current().span);
lhs = Expr::FieldAccess(Box::new(lhs), name, s);
}
continue;
}
// Index access
if matches!(op_tok.kind, TokenKind::LBracket) {
let idx = self.parse_expr(0)?;
self.expect(&TokenKind::RBracket)?;
let s = lhs.span().merge(&self.current().span);
lhs = Expr::IndexAccess(Box::new(lhs), Box::new(idx), s);
continue;
}
// Range
if matches!(op_tok.kind, TokenKind::DotDot | TokenKind::DotDotEq) {
let inclusive = matches!(op_tok.kind, TokenKind::DotDotEq);
let rhs = self.parse_expr(r_bp)?;