Add initial parser support for harmony iteration

src/preparser.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 641 matching lines @@
 
   Expect(i::Token::WHILE, CHECK_OK);
   Expect(i::Token::LPAREN, CHECK_OK);
   ParseExpression(true, CHECK_OK);
   Expect(i::Token::RPAREN, CHECK_OK);
   ParseStatement(ok);
   return Statement::Default();
 }
 
 
+bool PreParser::CheckInOrOf() {
+  if (peek() == i::Token::IN ||
+      (allow_for_of() &&
+       scanner_->is_next_contextual_keyword(v8::internal::CStrVector("of")))) {
+    Next();
+    return true;
+  }
+  return false;
+}
+
+
 PreParser::Statement PreParser::ParseForStatement(bool* ok) {
   // ForStatement ::
   //   'for' '(' Expression? ';' Expression? ';' Expression? ')' Statement
 
   Expect(i::Token::FOR, CHECK_OK);
   Expect(i::Token::LPAREN, CHECK_OK);
   if (peek() != i::Token::SEMICOLON) {
     if (peek() == i::Token::VAR || peek() == i::Token::CONST ||
         peek() == i::Token::LET) {
       bool is_let = peek() == i::Token::LET;
       int decl_count;
       VariableDeclarationProperties decl_props = kHasNoInitializers;
       ParseVariableDeclarations(
           kForStatement, &decl_props, &decl_count, CHECK_OK);
       bool accept_IN = decl_count == 1 &&
           !(is_let && decl_props == kHasInitializers);
-      if (peek() == i::Token::IN && accept_IN) {
-        Expect(i::Token::IN, CHECK_OK);
+      if (accept_IN && CheckInOrOf()) {
         ParseExpression(true, CHECK_OK);
         Expect(i::Token::RPAREN, CHECK_OK);
 
         ParseStatement(CHECK_OK);
         return Statement::Default();
       }
     } else {
       ParseExpression(false, CHECK_OK);
-      if (peek() == i::Token::IN) {
-        Expect(i::Token::IN, CHECK_OK);
+      if (CheckInOrOf()) {
         ParseExpression(true, CHECK_OK);
         Expect(i::Token::RPAREN, CHECK_OK);
 
         ParseStatement(CHECK_OK);
         return Statement::Default();
       }
     }
   }
 
   // Parsed initializer at this point.
@@ skipping 1110 matching lines @@
       backing_store_.Add(static_cast<byte>((ascii_length >> 14) | 0x80u));
     }
     backing_store_.Add(static_cast<byte>((ascii_length >> 7) | 0x80u));
   }
   backing_store_.Add(static_cast<byte>(ascii_length & 0x7f));
 
   backing_store_.AddBlock(bytes);
   return backing_store_.EndSequence().start();
 }
 } }  // v8::preparser