Frog: Fix parsing of hex literals with >31 bits

frog/parser.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // TODO(jimhug): Error recovery needs major work!
 /**
  * A simple recursive descent parser for the dart language.
  *
  * This parser is designed to be more permissive than the official
  * Dart grammar.  It is expected that many grammar errors would be
@@ skipping 1316 matching lines @@
     } else if (c >= 65/*A*/ && c <= 70/*F*/) {
       return c - 55;
     } else {
       return -1;
     }
   }
 
   static int parseHex(String hex) {
     var result = 0;
 
-    for (int i=0; i < hex.length; i++) {
+    for (int i = 0; i < hex.length; i++) {
       var digit = _hexDigit(hex.charCodeAt(i));
       assert(digit != -1);
-      result = (result << 4) + digit;
+      // Multiply by 16 rather than shift by 4 since that will result in a
+      // correct value for numbers that exceed the 32 bit precision of JS
+      // 'integers'.
+      // TODO: Figure out a better solution to integer truncation. Issue 638.
+      result = (result * 16) + digit;
     }
 
     return result;
   }
 
   finishNewExpression(int start, bool isConst) {
     var type = type();
     var name = null;
     if (_maybeEat(TokenKind.DOT)) {
       name = identifier();
@@ skipping 331 matching lines @@
   int _pos = 0;
   next() {
     var token = tokens[_pos];
     ++_pos;
     if (_pos == tokens.length) {
       parser.tokenizer = previousTokenizer;
     }
     return token;
   }
 }