Recover from fatal parser errors.

dart/pkg/compiler/lib/src/scanner/class_element_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.
 
 part of scanner;
 
 class ClassElementParser extends PartialParser {
   ClassElementParser(Listener listener) : super(listener);
 
   Token parseClassBody(Token token) => fullParseClassBody(token);
@@ skipping 31 matching lines @@
         message: "Node has not been computed for $this."));
     return cachedNode;
   }
 
   ClassNode parseNode(Compiler compiler) {
     if (cachedNode != null) return cachedNode;
     compiler.withCurrentElement(this, () {
       compiler.parser.measure(() {
         MemberListener listener = new MemberListener(compiler, this);
         Parser parser = new ClassElementParser(listener);
-        Token token = parser.parseTopLevelDeclaration(beginToken);
-        assert(identical(token, endToken.next));
-        cachedNode = listener.popNode();
-        assert(invariant(beginToken, listener.nodes.isEmpty,
-            message: "Non-empty listener stack: ${listener.nodes}"));
+        try {
+          Token token = parser.parseTopLevelDeclaration(beginToken);
+          assert(identical(token, endToken.next));
+          cachedNode = listener.popNode();
+          assert(
+              invariant(
+                  beginToken, listener.nodes.isEmpty,
+                  message: "Non-empty listener stack: ${listener.nodes}"));
+        } on ParserError catch (e) {
+          // TODO(ahe): Often, a ParserError is thrown while parsing the class
+          // body. This means that the stack actually contains most of the
+          // information synthesized below. Consider rewriting the parser so
+          // endClassDeclaration is called before parsing the class body.
+          Identifier name = new Identifier(findMyName(beginToken));
+          NodeList typeParameters = null;
+          Node supertype = null;
+          NodeList interfaces = listener.makeNodeList(0, null, null, ",");
+          Token extendsKeyword = null;
+          NodeList body = listener.makeNodeList(0, beginToken, endToken, null);
+          cachedNode = new ClassNode(
+              Modifiers.EMPTY, name, typeParameters, supertype, interfaces,
+              beginToken, extendsKeyword, body, endToken);
+          hasParseError = true;
+        }
       });
       compiler.patchParser.measure(() {
         if (isPatched) {
           // TODO(lrn): Perhaps extract functionality so it doesn't
           // need compiler.
           compiler.patchParser.parsePatchClassNode(patch);
         }
       });
     });
     return cachedNode;
@@ skipping 150 matching lines @@
 
   void endMetadata(Token beginToken, Token periodBeforeName, Token endToken) {
     popNode(); // Discard arguments.
     if (periodBeforeName != null) {
       popNode(); // Discard name.
     }
     popNode(); // Discard node (Send or Identifier).
     pushMetadata(new PartialMetadataAnnotation(beginToken, endToken));
   }
 }