From 56455044d04779ea10664d6aa9d328d45274c057 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Mon, 8 Sep 2014 00:35:08 -0700
Subject: [PATCH] Add math assignment operators, fix some precedences

---
 grammar.coffee               | 60 +++++++++++++++++++++---------------
 grammar_test/expressions.txt | 32 +++++++++++++++++++
 2 files changed, 68 insertions(+), 24 deletions(-)

diff --git a/grammar.coffee b/grammar.coffee
index c0c93c62d..bf11e0617 100644
--- a/grammar.coffee
+++ b/grammar.coffee
@@ -43,7 +43,7 @@ module.exports = compiler.grammar
 
     if_statement: -> seq(
       keyword("if"),
-      "(", err(@expression), ")",
+      @_paren_expression,
       @statement,
       optional(seq(
         keyword("else"),
@@ -91,14 +91,14 @@ module.exports = compiler.grammar
 
     while_statement: -> seq(
       keyword("while"),
-      "(", err(@expression), ")",
+      @_paren_expression,
       @statement)
 
     do_statement: -> seq(
       keyword("do"),
       @statement_block,
       keyword("while"),
-      "(", err(@expression), ")")
+      @_paren_expression)
 
     return_statement: -> seq(
       keyword("return"),
@@ -166,7 +166,11 @@ module.exports = compiler.grammar
       @rel_op,
       @type_op,
       @assignment,
-      seq("(", err(@expression), ")"))
+      @math_assignment,
+      @_paren_expression)
+
+    _paren_expression: -> seq(
+      "(", err(@expression), ")")
 
     function_call: -> seq(
       @expression,
@@ -198,6 +202,14 @@ module.exports = compiler.grammar
       "=",
       @expression))
 
+    math_assignment: -> prec(-2, seq(
+      choice(
+        @identifier,
+        @member_access,
+        @subscript_access)
+      choice("+=", "-=", "*=", "/="),
+      @expression))
+
     object: -> seq(
       "{", commaSep(err(@pair)), "}")
 
@@ -237,33 +249,33 @@ module.exports = compiler.grammar
       prec(1, seq(@expression, "||", @expression)))
 
     bitwise_op: -> choice(
-      prec(3, seq(@expression, ">>", @expression)),
-      prec(3, seq(@expression, "<<", @expression)),
-      prec(2, seq(@expression, "&", @expression)),
-      prec(1, seq(@expression, "|", @expression)))
+      prec(13, seq(@expression, ">>", @expression)),
+      prec(13, seq(@expression, "<<", @expression)),
+      prec(12, seq(@expression, "&", @expression)),
+      prec(11, seq(@expression, "|", @expression)))
 
     ternary: -> prec(-1, seq(
       @expression, "?", @expression, ":", @expression))
 
     math_op: -> choice(
-      prec(4, seq("-", @expression)),
-      prec(4, seq("+", @expression)),
-      prec(4, seq(@expression, "++")),
-      prec(4, seq(@expression, "--")),
-      prec(1, seq(@expression, "+", @expression)),
-      prec(1, seq(@expression, "-", @expression)),
-      prec(2, seq(@expression, "*", @expression)),
-      prec(2, seq(@expression, "/", @expression)))
+      prec(14, seq("-", @expression)),
+      prec(14, seq("+", @expression)),
+      prec(14, seq(@expression, "++")),
+      prec(14, seq(@expression, "--")),
+      prec(11, seq(@expression, "+", @expression)),
+      prec(11, seq(@expression, "-", @expression)),
+      prec(12, seq(@expression, "*", @expression)),
+      prec(12, seq(@expression, "/", @expression)))
 
     rel_op: -> choice(
-      seq(@expression, "<", @expression),
-      seq(@expression, "<=", @expression),
-      seq(@expression, "==", @expression),
-      seq(@expression, "===", @expression),
-      seq(@expression, "!=", @expression),
-      seq(@expression, "!==", @expression),
-      seq(@expression, ">=", @expression),
-      seq(@expression, ">", @expression))
+      prec(10, seq(@expression, "<", @expression)),
+      prec(10, seq(@expression, "<=", @expression)),
+      prec(10, seq(@expression, "==", @expression)),
+      prec(10, seq(@expression, "===", @expression)),
+      prec(10, seq(@expression, "!=", @expression)),
+      prec(10, seq(@expression, "!==", @expression)),
+      prec(10, seq(@expression, ">=", @expression)),
+      prec(10, seq(@expression, ">", @expression)))
 
     type_op: -> choice(
       prec(1, seq(keyword("typeof"), @expression)),
diff --git a/grammar_test/expressions.txt b/grammar_test/expressions.txt
index 89bff9d4a..4a5d8e036 100644
--- a/grammar_test/expressions.txt
+++ b/grammar_test/expressions.txt
@@ -321,3 +321,35 @@ x instanceof String;
 (program
   (expression_statement (type_op (identifier)))
   (expression_statement (type_op (identifier) (identifier))))
+
+==============================================
+Math assignment operators
+==============================================
+
+x += 1;
+y.z *= 3;
+
+---
+
+(program
+  (expression_statement
+    (math_assignment (identifier) (number)))
+  (expression_statement
+    (math_assignment (member_access (identifier) (identifier)) (number))))
+
+==============================================
+Operator precedence
+==============================================
+
+a <= b && c >= d;
+a.b = c ? d : e;
+
+---
+
+(program
+  (expression_statement (bool_op
+    (rel_op (identifier) (identifier))
+    (rel_op (identifier) (identifier))))
+  (expression_statement (assignment
+    (member_access (identifier) (identifier))
+    (ternary (identifier) (identifier) (identifier)))))