Better runtime type checks.

frog/tokenizer.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.
 // Generated by scripts/tokenizer_gen.py.
 
 class InterpStack {
   InterpStack next, previous;
   final int quote;
   final bool isMultiline;
   int depth;
@@ skipping 168 matching lines @@
   bool maybeEatHexDigit() {
     if (_index < _text.length && isHexDigit(_text.charCodeAt(_index))) {
       _index++;
       return true;
     }
     return false;
   }
 
   Token finishHex() {
     eatHexDigits();
-    return _finishToken(TokenKind.HEX_NUMBER);
+    return _finishToken(TokenKind.HEX_INTEGER);
   }
 
   Token finishNumber() {
     eatDigits();
 
     if (_peekChar() == 46/*.*/) {
       // Handle the case of 1.toString().
       _nextChar();
       if (isDigit(_peekChar())) {
         eatDigits();
+        return finishNumberExtra(TokenKind.DOUBLE);
       } else {
         _index--;
       }
     }
 
-    return finishNumberExtra();
+    return finishNumberExtra(TokenKind.INTEGER);
   }
 
-  Token finishNumberExtra() {
+  Token finishNumberExtra(int kind) {
     if (_maybeEatChar(101/*e*/) || _maybeEatChar(69/*E*/)) {
+      kind = TokenKind.DOUBLE;
       _maybeEatChar(45/*-*/);
       _maybeEatChar(43/*+*/);
       eatDigits();
     }
     if (_peekChar() != 0 && isIdentifierStart(_peekChar())) {
       _nextChar();
       // numbers cannot contain identifiers
       return _errorToken();
     }
 
-    return _finishToken(TokenKind.NUMBER);
+    return _finishToken(kind);
   }
 
   Token finishMultilineString(int quote) {
     while (true) {
       int ch = _nextChar();
       if (ch == 0) {
         final kind = quote == 34/*"*/ ?
             TokenKind.INCOMPLETE_MULTILINE_STRING_DQ :
             TokenKind.INCOMPLETE_MULTILINE_STRING_SQ;
         return _finishToken(kind);
@@ skipping 129 matching lines @@
     // According to the Unicode standard the high and low surrogate halves
     // used by UTF-16 (U+D800 through U+DFFF) and values above U+10FFFF
     // are not legal Unicode values.
     num n = Parser.parseHex(hex);
     return n < 0xD800 || n > 0xDFFF && n <= 0x10FFFF;
   }
 
   Token finishDot() {
     if (isDigit(_peekChar())) {
       eatDigits();
-      return finishNumberExtra();
+      return finishNumberExtra(TokenKind.DOUBLE);
     } else {
       return _finishToken(TokenKind.DOT);
     }
   }
 
   Token finishIdentifier() {
     while (_index < _text.length) {
       if (!isIdentifierPart(_text.charCodeAt(_index++))) {
         _index--;
         break;
       }
     }
     int kind = getIdentifierKind();
     if (_interpStack != null && _interpStack.depth == -1) {
       _interpStack.depth = 0;
     }
     if (kind == TokenKind.IDENTIFIER) {
       return _finishToken(TokenKind.IDENTIFIER);
     } else {
       return _finishToken(kind);
     }
   }
 }