Task: gather elements used in a unit.

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 'dart:math' as math;
 
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 274 matching lines @@
     new ResultDescriptor<List<AnalysisError>>(
         'SCAN_ERRORS', AnalysisError.NO_ERRORS, contributesTo: DART_ERRORS);
 
 /**
  * The [TypeProvider] of the context.
  */
 final ResultDescriptor<TypeProvider> TYPE_PROVIDER =
     new ResultDescriptor<TypeProvider>('TYPE_PROVIDER', null);
 
 /**
+ * The used [Element]s of a [LibraryUnitTarget].
+ */
+final ResultDescriptor<UsedElements> USED_ELEMENTS =
+    new ResultDescriptor<UsedElements>('USED_ELEMENTS', null);
+
+/**
  * The errors produced while verifying a compilation unit.
  *
  * The list will be empty if there were no errors, but will not be `null`.
  *
  * The result is only available for targets representing a Dart compilation unit.
  */
 final ResultDescriptor<List<AnalysisError>> VERIFY_ERRORS =
     new ResultDescriptor<List<AnalysisError>>(
         'VERIFY_ERRORS', AnalysisError.NO_ERRORS, contributesTo: DART_ERRORS);
 
@@ skipping 1352 matching lines @@
       element = definedNames[setterName];
       if (element != null) {
         newNames[setterName] = element;
       }
     }
     return newNames;
   }
 }
 
 /**
+ * A task that builds [USED_ELEMENTS] for a unit.
+ */
+class GatherUsedElementsTask extends SourceBasedAnalysisTask {
+  /**
+   * The name of the [RESOLVED_UNIT] input.
+   */
+  static const String UNIT_INPUT = 'UNIT_INPUT';
+
+  /**
+   * The task descriptor describing this kind of task.
+   */
+  static final TaskDescriptor DESCRIPTOR = new TaskDescriptor(
+      'GatherUsedElementsTask', createTask, buildInputs,
+      <ResultDescriptor>[USED_ELEMENTS]);
+
+  GatherUsedElementsTask(InternalAnalysisContext context, AnalysisTarget target)
+      : super(context, target);
+
+  @override
+  TaskDescriptor get descriptor => DESCRIPTOR;
+
+  @override
+  void internalPerform() {
+    CompilationUnit unit = getRequiredInput(UNIT_INPUT);
+    CompilationUnitElement unitElement = unit.element;
+    LibraryElement libraryElement = unitElement.library;
+    //
+    // Prepare visited elements.
+    //
+    GatherUsedElementsVisitor visitor =
+        new GatherUsedElementsVisitor(libraryElement);
+    unit.accept(visitor);
+    //
+    // Record outputs.
+    //
+    outputs[USED_ELEMENTS] = visitor.usedElements;
+  }
+
+  /**
+   * 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(LibraryUnitTarget target) {
+    return <String, TaskInput>{UNIT_INPUT: RESOLVED_UNIT.of(target)};
+  }
+
+  /**
+   * Create a [GatherUsedElementsTask] based on the given [target] in
+   * the given [context].
+   */
+  static GatherUsedElementsTask createTask(
+      AnalysisContext context, LibraryUnitTarget target) {
+    return new GatherUsedElementsTask(context, target);
+  }
+}
+
+/**
  * A task that generates [HINTS] for a unit.
  */
 class GenerateHintsTask extends SourceBasedAnalysisTask {
   /**
    * The name of the [RESOLVED_UNIT] input.
    */
   static const String UNIT_INPUT = 'UNIT_INPUT';
 
   /**
    * The task descriptor describing this kind of task.
@@ skipping 706 matching lines @@
   final Source target;
 
   _ExportSourceClosureTaskInput(this.target);
 
   @override
   TaskInputBuilder<List<Source>> createBuilder() =>
       new _SourceClosureTaskInputBuilder(target, _SourceClosureKind.EXPORT);
 }
 
 /**
+ * The kind of the source closure to build.
+ */
+enum _SourceClosureKind { IMPORT, EXPORT }
+
+/**
  * A [TaskInput] whose value is a list of library sources imported directly
  * or indirectly by the target [Source].
  */
 class _ImportSourceClosureTaskInput implements TaskInput<List<Source>> {
   final Source target;
 
   _ImportSourceClosureTaskInput(this.target);
 
   @override
   TaskInputBuilder<List<Source>> createBuilder() =>
       new _SourceClosureTaskInputBuilder(target, _SourceClosureKind.IMPORT);
 }
 
 /**
- * The kind of the source closure to build.
- */
-enum _SourceClosureKind { IMPORT, EXPORT }
-
-/**
  * A [TaskInputBuilder] to build values for [_ImportSourceClosureTaskInput].
  */
 class _SourceClosureTaskInputBuilder implements TaskInputBuilder<List<Source>> {
   final _SourceClosureKind kind;
   final Set<LibraryElement> _libraries = new HashSet<LibraryElement>();
   final Set<Source> _newSources = new HashSet<Source>();
 
   Source currentTarget;
 
   _SourceClosureTaskInputBuilder(Source librarySource, this.kind) {
@@ skipping 28 matching lines @@
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.first;
     _newSources.remove(currentTarget);
     return true;
   }
 }