improve parser recovery for import directives

pkg/analyzer/lib/src/generated/parser.dart

 // Copyright (c) 2014, 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.
 
 // This code was auto-generated, is not intended to be edited, and is subject to
 // significant change. Please see the README file for more information.
 
 library engine.parser;
 
 import "dart:math" as math;
@@ skipping 5934 matching lines @@
     }
     return new IfStatement(ifKeyword, leftParenthesis, condition,
         rightParenthesis, thenStatement, elseKeyword, elseStatement);
   }
 
   /**
    * Parse an import directive. The [commentAndMetadata] is the metadata to be
    * associated with the directive. Return the import directive that was parsed.
    *
    *     importDirective ::=
-   *         metadata 'import' stringLiteral ('as' identifier)? combinator*';'
+   *         metadata 'import' stringLiteral (deferred)? ('as' identifier)? combinator*';'
    */
   ImportDirective _parseImportDirective(CommentAndMetadata commentAndMetadata) {
     Token importKeyword = _expectKeyword(Keyword.IMPORT);
     StringLiteral libraryUri = _parseUri();
     Token deferredToken = null;
     Token asToken = null;
     SimpleIdentifier prefix = null;
     if (_matchesKeyword(Keyword.DEFERRED)) {
       deferredToken = getAndAdvance();
     }
     if (_matchesKeyword(Keyword.AS)) {
       asToken = getAndAdvance();
       prefix = parseSimpleIdentifier();
     } else if (deferredToken != null) {
       _reportErrorForCurrentToken(
           ParserErrorCode.MISSING_PREFIX_IN_DEFERRED_IMPORT);
+    } else if (!_matches(TokenType.SEMICOLON) &&
+        _tokenMatchesKeyword(_peek(), Keyword.AS)) {

[Brian Wilkerson, 2015/04/07 23:09:14]

We might want to allow either 'as', 'show' or 'hide' as the next token.

[danrubel, 2015/04/08 14:51:25]

Good suggestion. https://codereview.chromium.org/1068263002/

+      _reportErrorForCurrentToken(
+          ParserErrorCode.UNEXPECTED_TOKEN, [_currentToken]);
+      _advance();
+      asToken = getAndAdvance();
+      prefix = parseSimpleIdentifier();
     }
     List<Combinator> combinators = _parseCombinators();
     Token semicolon = _expectSemicolon();
     return new ImportDirective(commentAndMetadata.comment,
         commentAndMetadata.metadata, importKeyword, libraryUri, deferredToken,
         asToken, prefix, combinators, semicolon);
   }
 
   /**
    * Parse a list of initialized identifiers. The [commentAndMetadata] is the
@@ skipping 4581 matching lines @@
   }
 
   /**
    * Copy resolution data from the [fromNode] to the [toNode].
    */
   static void copyResolutionData(AstNode fromNode, AstNode toNode) {
     ResolutionCopier copier = new ResolutionCopier();
     copier._isEqualNodes(fromNode, toNode);
   }
 }