[Bug 15435] Lower constructor precedence

peter-b · peter-b · commit 693b73d22960 · 2015-11-11T15:07:58.000Z
Since there's some uncertainty about the correct precedence of
function &amp; constructor chunks, leave them approximately the same as
they before.
diff --git a/docs/lcb/notes/feature-precedence.md b/docs/lcb/notes/feature-precedence.md
@@ -7,15 +7,7 @@ defined set of 23 named precedence classes.  This is to ensure
 predictable and consistent interactions when multiple LCB operators
 are used in a single expression.
 
-There are two changes which are likely to significantly affect
-pre-existing LCB code:
-
-* "property", "subscript chunk", "function chunk" and "constructor
-  chunk" syntax classes now always have higher precedence than
-  arithmetic operators.  In particular, this change is likely to
-  require additional parentheses `(...)` around arithmetic operations
-  when using the LCB canvas API.
-
-* the precedence of the logical `not` operator has been reduced to
-  below that of comparison operators.  This may allow removal of
-  parentheses in the condition clauses of `if` statements.
+There only change that is likely to significantly affect pre-existing
+LCB code is the reduction in precedence of the logical `not` operator
+to below that of comparison operators.  This may allow removal of
+parentheses in the condition clauses of `if` statements.
diff --git a/docs/specs/lcb-precedence.md b/docs/specs/lcb-precedence.md
@@ -31,9 +31,8 @@ Lower precedence numbers are more tightly-binding.
 |       | subscript         | `tList[1]`, `tArray["key"]`   |
 | 3     | property          | `the paint of this canvas`    |
 |       | subscript chunk   | `char 2 of tString`           |
-|       | function chunk    | `the length of tList`         |
-|       | constructor       | `rectangle tList`             |
 | 4     | conversion        | `tString parsed as number`    |
+|       | function chunk    | `the offset of "o" in "foo"`  |
 | 5     | modifier          | `-tNum`, `bitwise not`        |
 | 6     | exponentiation    | `^`                           |
 | 7     | multiplication    | `/`,`*`,`mod`, `div`          |
@@ -43,9 +42,10 @@ Lower precedence numbers are more tightly-binding.
 | 10    | bitwise and       | `7 bitwise and 1`             |
 | 11    | bitwise xor       | `7 bitwise xor 5`             |
 | 12    | bitwise or        | `2 bitwise or 4`              |
-| 13    | comparison        | `<=`, `<`, `is`               |
+| 13    | constructor       | `rectangle tList`             |
+| 14    | comparison        | `<=`, `<`, `is`               |
 |       | classification    | `is a`                        |
-| 14    | logical not       | `not tBoolean`                |
-| 15    | logical and       | `Foo() and Bar()`             |
-| 16    | logical or        | `Foo() or Bar()`              |
-| 17    | sequence          | `,`                           |
+| 15    | logical not       | `not tBoolean`                |
+| 16    | logical and       | `Foo() and Bar()`             |
+| 17    | logical or        | `Foo() or Bar()`              |
+| 18    | sequence          | `,`                           |
diff --git a/toolchain/lc-compile/src/syntax.g b/toolchain/lc-compile/src/syntax.g
@@ -281,10 +281,9 @@
 
     'rule' MapSyntaxPrecedence(property -> 3)
     'rule' MapSyntaxPrecedence(subscriptchunk -> 3)
-    'rule' MapSyntaxPrecedence(functionchunk -> 3)
-    'rule' MapSyntaxPrecedence(constructor -> 3)
 
     'rule' MapSyntaxPrecedence(conversion -> 4)
+    'rule' MapSyntaxPrecedence(functionchunk -> 3)
 
     'rule' MapSyntaxPrecedence(modifier -> 5)
 
@@ -303,13 +302,15 @@
 
     'rule' MapSyntaxPrecedence(bitwiseor -> 12)
 
-    'rule' MapSyntaxPrecedence(comparison -> 13)
-    'rule' MapSyntaxPrecedence(classification -> 13)
+    'rule' MapSyntaxPrecedence(constructor -> 13)
+
+    'rule' MapSyntaxPrecedence(comparison -> 14)
+    'rule' MapSyntaxPrecedence(classification -> 14)
 
-    'rule' MapSyntaxPrecedence(logicalnot -> 14)
+    'rule' MapSyntaxPrecedence(logicalnot -> 15)
 
-    'rule' MapSyntaxPrecedence(logicaland -> 15)
+    'rule' MapSyntaxPrecedence(logicaland -> 16)
 
-    'rule' MapSyntaxPrecedence(logicalor -> 16)
+    'rule' MapSyntaxPrecedence(logicalor -> 17)
 
-    'rule' MapSyntaxPrecedence(sequence -> 17)
+    'rule' MapSyntaxPrecedence(sequence -> 18)
diff --git a/toolchain/lc-compile/src/types.g b/toolchain/lc-compile/src/types.g
@@ -340,6 +340,7 @@
     property,         -- the paint of tCanvas
     subscriptchunk,   -- char 5 of tString
     conversion,       -- tString parsed as number
+    functionchunk,    -- the length of tList
     modifier,         -- -tNumber, bitwise not tNumber
     exponentiation,   -- 2 ^ 10
     multiplication,   -- /, *, div, mod
@@ -349,7 +350,6 @@
     bitwiseand,       -- 5 bitwise and 1
     bitwisexor,       -- 5 bitwise xor 1
     bitwiseor,        -- 5 bitwise or 1
-    functionchunk,    -- the length of tList
     constructor,      -- rectangle tList
     comparison,       -- <=, <, is, =
     classification,   -- 5 is a number
