Peek past balanced parens to see if they are an expression or lambda.

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.
 
+
+/**
+ */
+interface TokenSource {
+  Token next();
+}
+
 class InterpStack {
   InterpStack next, previous;
   final int quote;
   final bool isMultiline;
   int depth;
 
   InterpStack(this.previous, this.quote, this.isMultiline): depth = -1;
 
   InterpStack pop() {
     return this.previous;
   }
 
   static InterpStack push(InterpStack stack, int quote, bool isMultiline) {
     var newStack = new InterpStack(stack, quote, isMultiline);
     if (stack != null) newStack.previous = stack;
     return newStack;
   }
 }
 
 /**
  * The base class for our tokenizer. The hand coded parts are in this file, with
  * the generated parts in the subclass Tokenizer.
  */
-class TokenizerBase extends TokenizerHelpers {
+class TokenizerBase extends TokenizerHelpers implements TokenSource {
   final SourceFile _source;
   final bool _skipWhitespace;
   String _text;
 
   int _index;
   int _startIndex;
 
   /** Keeps track of string interpolation state. */
   InterpStack _interpStack;
 
@@ skipping 344 matching lines @@
     if (_interpStack != null && _interpStack.depth == -1) {
       _interpStack.depth = 0;
     }
     if (kind == TokenKind.IDENTIFIER) {
       return _finishToken(TokenKind.IDENTIFIER);
     } else {
       return _finishToken(kind);
     }
   }
 }