Improve error recovery in parser.

dart/frog/leg/scanner/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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list.
  */
 class Parser {
   final Listener listener;
@@ skipping 259 matching lines @@
       token = parseType(token.next);
     } else {
       listener.handleNoType(token);
     }
     listener.endTypeVariable(token);
     return token;
   }
 
   bool optional(String value, Token token) => value === token.stringValue;
 
+  bool notEofOrValue(String value, Token token) {
+    return token.kind !== EOF_TOKEN && value !== token.stringValue;
+  }
+
   Token parseType(Token token) {
     // TODO(ahe): Rename this method to parseTypeOrVar?
     Token begin = token;
     int identifierCount = 1;
     if (isIdentifier(token)) {
       token = parseIdentifier(token);
       while (optional('.', token)) {
         // TODO(ahe): Validate that there are at most two identifiers.
         token = parseIdentifier(token.next);
         ++identifierCount;
@@ skipping 65 matching lines @@
       // error handling.
       final String value = token.stringValue;
       if (value === '(') {
         isField = false;
         break;
       } else if ((value === '=') || (value === ';') || (value === ',')) {
         isField = true;
         break;
       } else {
         token = listener.unexpected(token);
+        if (token.kind === EOF_TOKEN) {
+          // TODO(ahe): This is a hack. It would be better to tell the
+          // listener more explicitly that it must pop an identifier.
+          listener.endTopLevelFields(0, start, token);
+          return token;
+        }
       }
     }
     if (isField) {
       int fieldCount = 1;
       token = parseVariableInitializerOpt(token);
       while (optional(',', token)) {
         token = parseIdentifier(token.next);
         token = parseVariableInitializerOpt(token);
         ++fieldCount;
       }
@@ skipping 119 matching lines @@
   }
 
   Token parseClassBody(Token token) {
     Token begin = token;
     listener.beginClassBody(token);
     if (!optional('{', token)) {
       return listener.expectedBlock(token);
     }
     token = token.next;
     int count = 0;
-    while (!optional('}', token)) {
+    while (notEofOrValue('}', token)) {
       token = parseMember(token);
       ++count;
     }
     listener.endClassBody(count, begin, token);
     return token;
   }
 
   Token parseMember(Token token) {
     if (optional('factory', token)) {
       return parseFactoryMethod(token);
@@ skipping 162 matching lines @@
         listener.endReturnStatement(true, begin, token);
       } else {
         listener.endReturnStatement(true, begin, null);
       }
       return token;
     }
     Token begin = token;
     int statementCount = 0;
     listener.beginFunctionBody(begin);
     token = expect('{', token);
-    while (!optional('}', token)) {
+    while (notEofOrValue('}', token)) {
       token = parseStatement(token);
       ++statementCount;
     }
     listener.endFunctionBody(statementCount, begin, token);
     expect('}', token);
     return token;
   }
 
   Token parseStatement(Token token) {
     final value = token.stringValue;
@@ skipping 653 matching lines @@
     token = parseParenthesizedExpression(token);
     listener.endDoWhileStatement(doToken, whileToken, token);
     return expectSemicolon(token);
   }
 
   Token parseBlock(Token token) {
     Token begin = token;
     listener.beginBlock(begin);
     int statementCount = 0;
     token = expect('{', token);
-    while (!optional('}', token)) {
+    while (notEofOrValue('}', token)) {
       token = parseStatement(token);
       ++statementCount;
     }
     listener.endBlock(statementCount, begin, token);
     return expect('}', token);
   }
 
   Token parseThrowStatement(Token token) {
     Token throwToken = token;
     listener.beginThrowStatement(throwToken);
@@ skipping 71 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }