Bug 1066234 - Part 1: Parser support for 'extends' in ES6 Classes. (r=jorendorff)

js/src/frontend/Parser.cpp

@@ -5851,13 +5851,6 @@ Parser<FullParseHandler>::classStatement()
         return null();
     }
 
-    // Because the binding definitions keep track of their blockId, we need to
-    // create at least the inner binding later. Keep track of the name's position
-    // in order to provide it for the nodes created later.
-    TokenPos namePos = pos();
-
-    MUST_MATCH_TOKEN(TOK_LC, JSMSG_CURLY_BEFORE_CLASS);
-
     bool savedStrictness = setLocalStrictMode(true);
 
     StmtInfoPC classStmt(context);
@@ -5865,6 +5858,25 @@ Parser<FullParseHandler>::classStatement()
     if (!classBlock)
         return null();
 
+    // Because the binding definitions keep track of their blockId, we need to
+    // create at least the inner binding later. Keep track of the name's position
+    // in order to provide it for the nodes created later.
+    TokenPos namePos = pos();
+
+    ParseNode *classHeritage = null();
+    bool hasHeritage;
+    if (!tokenStream.matchToken(&hasHeritage, TOK_EXTENDS))
+        return null();
+    if (hasHeritage) {
+        if (!tokenStream.getToken(&tt))
+            return null();
+        classHeritage = memberExpr(tt, true);
+        if (!classHeritage)
+            return null();
+    }
+
+    MUST_MATCH_TOKEN(TOK_LC, JSMSG_CURLY_BEFORE_CLASS);
+
     ParseNode *classMethods = propertyList(ClassBody);
     if (!classMethods)
         return null();
@@ -5886,7 +5898,7 @@ Parser<FullParseHandler>::classStatement()
 
     MOZ_ALWAYS_TRUE(setLocalStrictMode(savedStrictness));
 
-    return handler.newClass(nameNode, null(), classBlock);
+    return handler.newClass(nameNode, classHeritage, classBlock);
 }
 
 template <>

js/src/frontend/TokenKind.h

@@ -111,6 +111,7 @@
     macro(EXPORT,       "keyword 'export'") \
     macro(IMPORT,       "keyword 'import'") \
     macro(CLASS,        "keyword 'class'") \
+    macro(EXTENDS,      "keyword 'extends'") \
     macro(RESERVED,     "reserved keyword") \
     /* reserved keywords in strict mode */ \
     macro(STRICT_RESERVED, "reserved keyword") \

js/src/frontend/TokenStream.cpp

@@ -979,6 +979,7 @@ TokenStream::checkForKeyword(const KeywordInfo *kw, TokenKind *ttp)
     if (kw->tokentype == TOK_RESERVED
 #ifndef JS_HAS_CLASSES
         || kw->tokentype == TOK_CLASS
+        || kw->tokentype == TOK_EXTENDS
 #endif
         )
     {

js/src/vm/Keywords.h

@@ -44,9 +44,9 @@
     macro(import, import, TOK_IMPORT, JSVERSION_DEFAULT) \
     macro(export, export, TOK_EXPORT, JSVERSION_DEFAULT) \
     macro(class, class_, TOK_CLASS, JSVERSION_DEFAULT) \
+    macro(extends, extends, TOK_EXTENDS, JSVERSION_DEFAULT) \
     /* Reserved keywords. */ \
     macro(enum, enum_, TOK_RESERVED, JSVERSION_DEFAULT) \
-    macro(extends, extends, TOK_RESERVED, JSVERSION_DEFAULT) \
     macro(super, super, TOK_RESERVED, JSVERSION_DEFAULT) \
     /* Future reserved keywords, but only in strict mode. */ \
     macro(implements, implements, TOK_STRICT_RESERVED, JSVERSION_DEFAULT) \