Use a poor man's incremental parser to perform incremental resolution.

pkg/analyzer/lib/src/generated/engine.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;
 
 import "dart:math" as math;
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/src/task/task_dart.dart';
 
 import 'ast.dart';
 import 'constant.dart';
 import 'element.dart';
 import 'error.dart';
 import 'error_verifier.dart';
 import 'html.dart' as ht;
 import 'incremental_scanner.dart';
-import 'incremental_resolver.dart' show IncrementalResolver;
+import 'incremental_resolver.dart' show IncrementalResolver,
+    poorMansIncrementalResolution;
 import 'instrumentation.dart';
 import 'java_core.dart';
 import 'java_engine.dart';
 import 'parser.dart' show Parser, IncrementalParser;
 import 'resolver.dart';
 import 'scanner.dart';
 import 'sdk.dart' show DartSdk;
 import 'source.dart';
 import 'utilities_collection.dart';
 import 'utilities_general.dart';
@@ skipping 2877 matching lines @@
    * @param source the source whose contents are being overridden
    * @param contents the new contents of the source
    */
   bool _contentsChanged(Source source, String contents) {
     bool changed = false;
     String originalContents = _contentCache.setContents(source, contents);
     if (contents != null) {
       if (contents != originalContents) {
         _incrementalAnalysisCache =
             IncrementalAnalysisCache.clear(_incrementalAnalysisCache, source);
-        _sourceChanged(source);
+        if (!analysisOptions.incremental ||
+            !_tryPoorMansIncrementalResolution(source, contents)) {
+          _sourceChanged(source);
+        }
         changed = true;
         SourceEntry sourceEntry = _cache.get(source);
         if (sourceEntry != null) {
           sourceEntry.modificationTime =
               _contentCache.getModificationStamp(source);
           sourceEntry.setValue(SourceEntry.CONTENT, contents);
         }
       }
     } else if (originalContents != null) {
       _incrementalAnalysisCache =
@@ skipping 1983 matching lines @@
       dartEntry.recordContentError(
           new CaughtException(
               new AnalysisException("This source was marked as being deleted"),
               null));
     }
     _workManager.remove(source);
     _removeFromPriorityOrder(source);
   }
 
   /**
+   * TODO(scheglov) A hackish, limited incremental resolution implementation.
+   */
+  bool _tryPoorMansIncrementalResolution(Source unitSource, String newCode) {
+    List<Source> librarySources = getLibrariesContaining(unitSource);
+    if (librarySources.length != 1) {
+      return false;
+    }
+    CompilationUnit oldUnit =
+        getResolvedCompilationUnit2(unitSource, librarySources[0]);
+    bool success = poorMansIncrementalResolution(typeProvider, oldUnit, newCode);
+    if (!success) {
+      return false;
+    }
+    ChangeNoticeImpl notice = _getNotice(unitSource);
+    notice.compilationUnit = oldUnit;
+    // TODO(scheglov) apply updated errors
+    {
+      LineInfo lineInfo = getLineInfo(unitSource);
+      DartEntry dartEntry = _cache.get(unitSource);
+      notice.setErrors(dartEntry.allErrors, lineInfo);
+    }
+    return true;
+  }
+
+  /**
    * <b>Note:</b> This method must only be invoked while we are synchronized on [cacheLock].
    *
    * @param source the source that has been removed
    */
   void _sourceRemoved(Source source) {
     SourceEntry sourceEntry = _cache.get(source);
     if (sourceEntry is HtmlEntry) {
       _invalidateAngularResolution(sourceEntry);
     } else if (sourceEntry is DartEntry) {
       HashSet<Source> libraries = new HashSet<Source>();
@@ skipping 9898 matching lines @@
 
   @override
   Object visitPolymerTagDartElement(PolymerTagDartElement element) {
     if (element.name == PolymerHtmlUnitBuilder_this._elementName) {
       throw new PolymerHtmlUnitBuilder_FoundTagDartElementError(
           element as PolymerTagDartElementImpl);
     }
     return null;
   }
 }