Keep more analysis results that don't change when a source is changed.

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, 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.
 
 library analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 421 matching lines @@
  *
  * The result is only available for [Source]s representing a library.
  */
 final ResultDescriptor<LibraryElement> LIBRARY_ELEMENT1 =
     new ResultDescriptor<LibraryElement>('LIBRARY_ELEMENT1', null,
         cachingPolicy: ELEMENT_CACHING_POLICY);
 
 /**
  * The partial [LibraryElement] associated with a library.
  *
- * In addition to [LIBRARY_ELEMENT1] [LibraryElement.imports] and
+ * In addition to [LIBRARY_ELEMENT1] also [LibraryElement.imports] and
  * [LibraryElement.exports] are set.
  *
  * The result is only available for [Source]s representing a library.
  */
 final ResultDescriptor<LibraryElement> LIBRARY_ELEMENT2 =
     new ResultDescriptor<LibraryElement>('LIBRARY_ELEMENT2', null,
         cachingPolicy: ELEMENT_CACHING_POLICY);
 
 /**
  * The partial [LibraryElement] associated with a library.
@@ skipping 1768 matching lines @@
       outputs[LIBRARY_CYCLE_DEPENDENCIES] = [];
     }
   }
 
   /**
    * Return a map from the names of the inputs of this kind of task to the task
    * input descriptors describing those inputs for a task with the
    * given [target].
    */
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
+    // TODO(scheglov) Why the target is LibrarySpecificUnit?

[Brian Wilkerson, 2016/06/27 13:59:00]

This is addressed by another CL.

     LibrarySpecificUnit unit = target;
     return <String, TaskInput>{
       LIBRARY_ELEMENT_INPUT: LIBRARY_ELEMENT2.of(unit.library),
       'resolveReachableLibraries': READY_LIBRARY_ELEMENT2.of(unit.library),
     };
   }
 
   /**
    * Create a [ComputeLibraryCycleTask] based on the
    * given [target] in the given [context].
@@ skipping 300 matching lines @@
     Source targetSource = null;
     if (target is Source) {
       targetSource = target;
     }
     if (target is LibrarySpecificUnit) {
       targetSource = target.library;
     }
     if (target is Element) {
       targetSource = target.source;
     }
-    // Keep results that are updated incrementally.
-    // If we want to analyze only some references to the source being changed,
-    // we need to keep the same instances of CompilationUnitElement and
-    // LibraryElement.
+    // Keep results that don't change: any library.
+    if (_isTaskResult(BuildLibraryElementTask.DESCRIPTOR, descriptor) ||
+        _isTaskResult(BuildDirectiveElementsTask.DESCRIPTOR, descriptor) ||
+        _isTaskResult(ResolveDirectiveElementsTask.DESCRIPTOR, descriptor) ||
+        _isTaskResult(BuildEnumMemberElementsTask.DESCRIPTOR, descriptor) ||
+        _isTaskResult(BuildSourceExportClosureTask.DESCRIPTOR, descriptor) ||
+        _isTaskResult(ReadyLibraryElement2Task.DESCRIPTOR, descriptor) ||
+        _isTaskResult(ComputeLibraryCycleTask.DESCRIPTOR, descriptor)) {
+      return DeltaResult.KEEP_CONTINUE;
+    }
+    // Keep results that don't change: changed library.
     if (targetSource == source) {
-      if (ScanDartTask.DESCRIPTOR.results.contains(descriptor)) {
-        return DeltaResult.KEEP_CONTINUE;
-      }
-      if (ParseDartTask.DESCRIPTOR.results.contains(descriptor)) {
-        return DeltaResult.KEEP_CONTINUE;
-      }
-      if (BuildCompilationUnitElementTask.DESCRIPTOR.results
-          .contains(descriptor)) {
-        return DeltaResult.KEEP_CONTINUE;
-      }
-      if (BuildLibraryElementTask.DESCRIPTOR.results.contains(descriptor)) {
+      if (_isTaskResult(ScanDartTask.DESCRIPTOR, descriptor) ||
+          _isTaskResult(ParseDartTask.DESCRIPTOR, descriptor) ||
+          _isTaskResult(
+              BuildCompilationUnitElementTask.DESCRIPTOR, descriptor) ||
+          _isTaskResult(BuildLibraryElementTask.DESCRIPTOR, descriptor)) {
         return DeltaResult.KEEP_CONTINUE;
       }
       return DeltaResult.INVALIDATE;
     }
+    // Keep results that don't change: dependent library.
+    if (targetSource != source) {
+      if (_isTaskResult(BuildPublicNamespaceTask.DESCRIPTOR, descriptor)) {
+        return DeltaResult.KEEP_CONTINUE;
+      }
+    }
     // Use the target library dependency information to decide whether
     // the delta affects the library.
     if (targetSource != null) {
       List<Source> librarySources =
           context.getLibrariesContaining(targetSource);
       int length = librarySources.length;
       for (int i = 0; i < length; i++) {
         Source librarySource = librarySources[i];
         AnalysisCache cache = context.analysisCache;
         ReferencedNames referencedNames =
             cache.getValue(librarySource, REFERENCED_NAMES);
         if (referencedNames == null) {
           return DeltaResult.INVALIDATE;
         }
         referencedNames.addChangedElements(this);
         if (referencedNames.isAffectedBy(this)) {
           return DeltaResult.INVALIDATE;
         }
       }
       return DeltaResult.STOP;
     }
     // We don't know what to do with the given target, invalidate it.
     return DeltaResult.INVALIDATE;
   }
 
   static bool _isPrivateName(String name) => name.startsWith('_');
+
+  static bool _isTaskResult(
+      TaskDescriptor taskDescriptor, ResultDescriptor result) {
+    return taskDescriptor.results.contains(result);
+  }
 }
 
 /**
  * A task that merges all of the errors for a single source into a single list
  * of errors.
  */
 class DartErrorsTask extends SourceBasedAnalysisTask {
   /**
    * The task descriptor describing this kind of task.
    */
@@ skipping 3645 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }