Add support for tasks to determine whether they are appropriate for a given target

pkg/analyzer/lib/task/model.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.task.model;
 
 import 'dart:collection';
 import 'dart:developer';
 
 import 'package:analyzer/src/generated/engine.dart' hide AnalysisTask;
@@ skipping 18 matching lines @@
 
 /**
  * A function that takes the target for which a task will produce results and
  * returns a map from input names to descriptions of the analysis results needed
  * by the task in order for the task to be performed. Such functions are passed
  * to a [TaskDescriptor] to be used to determine the inputs needed by the task.
  */
 typedef Map<String, TaskInput> CreateTaskInputs(AnalysisTarget target);
 
 /**
+ * A function that takes the target for which a task will produce results and
+ * returns `true` if the task is appropriate for thetarget. Such functions are

[Paul Berry, 2016/01/25 20:12:40]

s/thetarget/the target/

[Brian Wilkerson, 2016/01/25 20:27:36]

Done

+ * passed to a [TaskDescriptor] to be used to determine the inputs needed by the
+ * task.
+ */
+typedef bool IsAppropriateFor(AnalysisTarget target);
+
+/**
  * A function that converts an object of the type [B] into a [TaskInput].
  * This is used, for example, by a [ListTaskInput] to create task inputs
  * for each value in a list of values.
  */
 typedef TaskInput<E> UnaryFunction<B, E>(B object);
 
 /**
  * An [AnalysisTarget] wrapper for an [AnalysisContext].
  */
 class AnalysisContextTarget implements AnalysisTarget {
@@ skipping 299 matching lines @@
  * A description of an input to an [AnalysisTask] that can be used to compute
  * that input.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class ListTaskInput<E> implements TaskInput<List<E>> {
   /**
    * Return a task input that can be used to compute a flatten list whose
    * elements are combined [subListResult]'s associated with those elements.
    */
-  ListTaskInput /*<V>*/ toFlattenListOf /*<V>*/ (
-      ListResultDescriptor /*<V>*/ subListResult);
+  ListTaskInput/*<V>*/ toFlattenListOf/*<V>*/(
+      ListResultDescriptor/*<V>*/ subListResult);
 
   /**
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing the elements of this input to the [mapper] function.
    */
-  ListTaskInput /*<V>*/ toList /*<V>*/ (
-      UnaryFunction<E, dynamic /*<=V>*/ > mapper);
+  ListTaskInput/*<V>*/ toList/*<V>*/(UnaryFunction<E, dynamic/*<=V>*/ > mapper);
 
   /**
    * Return a task input that can be used to compute a list whose elements are
    * [valueResult]'s associated with those elements.
    */
-  ListTaskInput /*<V>*/ toListOf /*<V>*/ (ResultDescriptor /*<V>*/ valueResult);
+  ListTaskInput/*<V>*/ toListOf/*<V>*/(ResultDescriptor/*<V>*/ valueResult);
 
   /**
    * Return a task input that can be used to compute a map whose keys are the
    * elements of this input and whose values are the result of passing the
    * corresponding key to the [mapper] function.
    */
-  MapTaskInput<E, dynamic /*=V*/ > toMap /*<V>*/ (
-      UnaryFunction<E, dynamic /*=V*/ > mapper);
+  MapTaskInput<E, dynamic/*=V*/ > toMap/*<V>*/(
+      UnaryFunction<E, dynamic/*=V*/ > mapper);
 
   /**
    * Return a task input that can be used to compute a map whose keys are the
    * elements of this input and whose values are the [valueResult]'s associated
    * with those elements.
    */
-  MapTaskInput<AnalysisTarget, dynamic /*=V*/ > toMapOf /*<V>*/ (
-      ResultDescriptor /*<V>*/ valueResult);
+  MapTaskInput<AnalysisTarget, dynamic/*=V*/ > toMapOf/*<V>*/(
+      ResultDescriptor/*<V>*/ valueResult);
 }
 
 /**
  * A description of an input with a [Map] based values.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class MapTaskInput<K, V> implements TaskInput<Map<K, V>> {
   /**
    * [V] must be a [List].
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing keys [K] and the corresponding elements of [V] to
    * the [mapper] function.
    */
-  TaskInput<List /*<E>*/ > toFlattenList /*<E>*/ (
-      BinaryFunction<K, dynamic /*element of V*/, dynamic /*=E*/ > mapper);
+  TaskInput<List/*<E>*/ > toFlattenList/*<E>*/(
+      BinaryFunction<K, dynamic /*element of V*/, dynamic/*=E*/ > mapper);
 }
 
 /**
  * A policy object that can compute sizes of results and provide the maximum
  * active and idle sizes that can be kept in the cache.
  *
  * All the [ResultDescriptor]s with the same [ResultCachingPolicy] instance
  * share the same total size in a cache.
  *
  * Clients may implement this class when implementing plugins.
@@ skipping 104 matching lines @@
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class TaskDescriptor {
   /**
    * Initialize a newly created task descriptor to have the given [name] and to
    * describe a task that takes the inputs built using the given [inputBuilder],
    * and produces the given [results]. The [buildTask] will be used to create
    * the instance of [AnalysisTask] thusly described.
    */
-  factory TaskDescriptor(
-      String name,
-      BuildTask buildTask,
-      CreateTaskInputs inputBuilder,
-      List<ResultDescriptor> results) = TaskDescriptorImpl;
+  factory TaskDescriptor(String name, BuildTask buildTask,
+      CreateTaskInputs inputBuilder, List<ResultDescriptor> results,
+      {IsAppropriateFor isAppropriateFor}) = TaskDescriptorImpl;
 
   /**
    * Return the builder used to build the inputs to the task.
    */
   CreateTaskInputs get createTaskInputs;
 
   /**
    * Return the name of the task being described.
    */
   String get name;
 
   /**
    * Return a list of the analysis results that will be computed by this task.
    */
   List<ResultDescriptor> get results;
 
   /**
    * Create and return a task that is described by this descriptor that can be
    * used to compute results based on the given [inputs].
    */
   AnalysisTask createTask(AnalysisContext context, AnalysisTarget target,
       Map<String, dynamic> inputs);
+
+  /**
+   * Return `true` if this task is appropriate for the given [target].
+   */
+  bool isAppropriateFor(AnalysisTarget target);
 }
 
 /**
  * A description of an input to an [AnalysisTask] that can be used to compute
  * that input.
  *
  * Clients may not extend, implement or mix-in this class.
  */
 abstract class TaskInput<V> {
   /**
    * Create and return a builder that can be used to build this task input.
    */
   TaskInputBuilder<V> createBuilder();
 
   /**
    * Return a task input that can be used to compute a list whose elements are
    * the result of passing the result of this input to the [mapper] function.
    */
-  ListTaskInput /*<E>*/ mappedToList /*<E>*/ (List /*<E>*/ mapper(V value));
+  ListTaskInput/*<E>*/ mappedToList/*<E>*/(List/*<E>*/ mapper(V value));
 }
 
 /**
  * An object used to build the value associated with a single [TaskInput].
  *
  * All builders work by requesting one or more results (each result being
  * associated with a target). The interaction pattern is modeled after the class
  * [Iterator], in which the method [moveNext] is invoked to move from one result
  * request to the next. The getters [currentResult] and [currentTarget] are used
  * to get the result and target of the current request. The value of the result
@@ skipping 151 matching lines @@
   /**
    * A work should be done, but without any special urgency.
    */
   NORMAL,
 
   /**
    * Nothing to do.
    */
   NONE
 }