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[Bug 15435] Lower constructor precedence
Since there's some uncertainty about the correct precedence of function & constructor chunks, leave them approximately the same as they before.
1 parent a7a4343 commit 693b73d

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Lines changed: 21 additions & 28 deletions

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‎docs/lcb/notes/feature-precedence.md‎

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Original file line numberDiff line numberDiff line change
@@ -7,15 +7,7 @@ defined set of 23 named precedence classes. This is to ensure
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predictable and consistent interactions when multiple LCB operators
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are used in a single expression.
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There are two changes which are likely to significantly affect
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pre-existing LCB code:
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* "property", "subscript chunk", "function chunk" and "constructor
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chunk" syntax classes now always have higher precedence than
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arithmetic operators. In particular, this change is likely to
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require additional parentheses `(...)` around arithmetic operations
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when using the LCB canvas API.
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* the precedence of the logical `not` operator has been reduced to
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below that of comparison operators. This may allow removal of
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parentheses in the condition clauses of `if` statements.
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There only change that is likely to significantly affect pre-existing
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LCB code is the reduction in precedence of the logical `not` operator
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to below that of comparison operators. This may allow removal of
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parentheses in the condition clauses of `if` statements.

‎docs/specs/lcb-precedence.md‎

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Original file line numberDiff line numberDiff line change
@@ -31,9 +31,8 @@ Lower precedence numbers are more tightly-binding.
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| | subscript | `tList[1]`, `tArray["key"]` |
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| 3 | property | `the paint of this canvas` |
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| | subscript chunk | `char 2 of tString` |
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| | function chunk | `the length of tList` |
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| | constructor | `rectangle tList` |
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| 4 | conversion | `tString parsed as number` |
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| | function chunk | `the offset of "o" in "foo"` |
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| 5 | modifier | `-tNum`, `bitwise not` |
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| 6 | exponentiation | `^` |
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| 7 | multiplication | `/`,`*`,`mod`, `div` |
@@ -43,9 +42,10 @@ Lower precedence numbers are more tightly-binding.
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| 10 | bitwise and | `7 bitwise and 1` |
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| 11 | bitwise xor | `7 bitwise xor 5` |
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| 12 | bitwise or | `2 bitwise or 4` |
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| 13 | comparison | `<=`, `<`, `is` |
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| 13 | constructor | `rectangle tList` |
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| 14 | comparison | `<=`, `<`, `is` |
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| | classification | `is a` |
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| 14 | logical not | `not tBoolean` |
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| 15 | logical and | `Foo() and Bar()` |
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| 16 | logical or | `Foo() or Bar()` |
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| 17 | sequence | `,` |
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| 15 | logical not | `not tBoolean` |
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| 16 | logical and | `Foo() and Bar()` |
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| 17 | logical or | `Foo() or Bar()` |
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| 18 | sequence | `,` |

‎toolchain/lc-compile/src/syntax.g‎

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@@ -281,10 +281,9 @@
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'rule' MapSyntaxPrecedence(property -> 3)
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'rule' MapSyntaxPrecedence(subscriptchunk -> 3)
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'rule' MapSyntaxPrecedence(functionchunk -> 3)
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'rule' MapSyntaxPrecedence(constructor -> 3)
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'rule' MapSyntaxPrecedence(conversion -> 4)
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'rule' MapSyntaxPrecedence(functionchunk -> 3)
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'rule' MapSyntaxPrecedence(modifier -> 5)
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@@ -303,13 +302,15 @@
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'rule' MapSyntaxPrecedence(bitwiseor -> 12)
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'rule' MapSyntaxPrecedence(comparison -> 13)
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'rule' MapSyntaxPrecedence(classification -> 13)
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'rule' MapSyntaxPrecedence(constructor -> 13)
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'rule' MapSyntaxPrecedence(comparison -> 14)
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'rule' MapSyntaxPrecedence(classification -> 14)
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'rule' MapSyntaxPrecedence(logicalnot -> 14)
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'rule' MapSyntaxPrecedence(logicalnot -> 15)
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'rule' MapSyntaxPrecedence(logicaland -> 15)
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'rule' MapSyntaxPrecedence(logicaland -> 16)
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'rule' MapSyntaxPrecedence(logicalor -> 16)
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'rule' MapSyntaxPrecedence(logicalor -> 17)
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'rule' MapSyntaxPrecedence(sequence -> 17)
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'rule' MapSyntaxPrecedence(sequence -> 18)

‎toolchain/lc-compile/src/types.g‎

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Original file line numberDiff line numberDiff line change
@@ -340,6 +340,7 @@
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property, -- the paint of tCanvas
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subscriptchunk, -- char 5 of tString
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conversion, -- tString parsed as number
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functionchunk, -- the length of tList
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modifier, -- -tNumber, bitwise not tNumber
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exponentiation, -- 2 ^ 10
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multiplication, -- /, *, div, mod
@@ -349,7 +350,6 @@
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bitwiseand, -- 5 bitwise and 1
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bitwisexor, -- 5 bitwise xor 1
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bitwiseor, -- 5 bitwise or 1
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functionchunk, -- the length of tList
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constructor, -- rectangle tList
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comparison, -- <=, <, is, =
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classification, -- 5 is a number

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