Add support code to make fixes easier in plugins

R=scheglov@google.com

Review-Url: https://codereview.chromium.org/2962903002 .

pkg/analysis_server/lib/plugin/edit/fix/fix_core.dart

@@ -9,6 +9,7 @@ import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart'
     show SourceChange;
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
 
 /**
  * A description of a single proposed fix for some problem.
@@ -27,7 +28,7 @@ class Fix {
    */
   static final Comparator<Fix> SORT_BY_RELEVANCE =
       (Fix firstFix, Fix secondFix) =>
-          firstFix.kind.relevance - secondFix.kind.relevance;
+          firstFix.kind.priority - secondFix.kind.priority;
 
   /**
    * A description of the fix being proposed.
@@ -85,40 +86,3 @@ abstract class FixContributor {
    */
   Future<List<Fix>> computeFixes(FixContext context);
 }
-
-/**
- * A description of a class of fixes. Instances are intended to hold the
- * information that is common across a number of fixes and to be shared by those
- * fixes. For example, if an unnecessary cast is found then one of the suggested
- * fixes will be to remove the cast. If there are multiple unnecessary casts in
- * a single file, then there will be multiple fixes, one per occurrence, but
- * they will all share the same kind.
- *
- * Clients may not extend, implement or mix-in this class.
- */
-class FixKind {
-  /**
-   * The name of this kind of fix, used for debugging.
-   */
-  final String name;
-
-  /**
-   * The relevance of this kind of fix for the kind of error being addressed.
-   */
-  final int relevance;
-
-  /**
-   * A human-readable description of the changes that will be applied by this
-   * kind of fix.
-   */
-  final String message;
-
-  /**
-   * Initialize a newly created kind of fix to have the given [name],
-   * [relevance] and [message].
-   */
-  const FixKind(this.name, this.relevance, this.message);
-
-  @override
-  String toString() => name;
-}

pkg/analysis_server/lib/src/services/correction/fix.dart

@@ -9,6 +9,7 @@ import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/parser.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
 
 /**
  * Return true if this [errorCode] is likely to have a fix associated with it.

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

@@ -44,6 +44,7 @@ import 'package:analyzer_plugin/protocol/protocol_common.dart'
     hide AnalysisError, Element, ElementKind;
 import 'package:analyzer_plugin/src/utilities/string_utilities.dart';
 import 'package:analyzer_plugin/utilities/change_builder/change_builder_dart.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart' hide FixContributor;
 import 'package:analyzer_plugin/utilities/range_factory.dart';
 import 'package:path/path.dart';
 

pkg/analysis_server/test/services/correction/fix_test.dart

@@ -21,6 +21,7 @@ import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart'
     hide AnalysisError;
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 

pkg/analyzer_plugin/lib/utilities/fixes/fix_contributor_mixin.dart

@@ -0,0 +1,67 @@
+// Copyright (c) 2017, 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.
+
+import 'package:analyzer/error/error.dart';
+import 'package:analyzer/src/generated/java_core.dart';
+import 'package:analyzer_plugin/protocol/protocol_common.dart'
+    hide AnalysisError;
+import 'package:analyzer_plugin/protocol/protocol_generated.dart';
+import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
+import 'package:analyzer_plugin/utilities/fixes/fixes.dart';
+
+/**
+ * A partial implementation of a [FixContributor] that iterates over the list of
+ * errors and provides a utility method to make it easier to add fixes.
+ *
+ * Clients may not extend or implement this class, but are allowed to use it as
+ * a mix-in when creating a subclass of [FixContributor].
+ */
+abstract class FixContributorMixin implements FixContributor {
+  /**
+   * The request that specifies the fixes that are to be built.
+   */
+  DartFixesRequest request;
+
+  /**
+   * The collector to which fixes should be added.
+   */
+  FixCollector collector;
+
+  /**
+   * Add a fix for the given [error]. Use the [kind] of the fix to get the
+   * message and priority, and use the change [builder] to get the edits that
+   * comprise the fix. If the message has parameters, then use the list of
+   * [args] to populate the message.
+   */
+  void addFix(AnalysisError error, FixKind kind, ChangeBuilder builder,
+      {List<Object> args: null}) {
+    SourceChange change = builder.sourceChange;
+    if (change.edits.isEmpty) {
+      return;
+    }
+    change.message = formatList(kind.message, args);
+    collector.addFix(error,
+        new PrioritizedSourceChange(kind.priority, builder.sourceChange));
+  }
+
+  @override
+  void computeFixes(DartFixesRequest request, FixCollector collector) {
+    this.request = request;
+    this.collector = collector;
+    try {
+      for (AnalysisError error in request.errorsToFix) {
+        computeFixesForError(error);
+      }
+    } finally {
+      this.request = null;
+      this.collector = null;
+    }
+  }
+
+  /**
+   * Compute the fixes that are appropriate for the given [error] and add them
+   * to the fix [collector].
+   */
+  void computeFixesForError(AnalysisError error);
+}

pkg/analyzer_plugin/lib/utilities/fixes/fixes.dart

@@ -108,3 +108,42 @@ class FixGenerator {
     return new GeneratorResult(result, notifications);
   }
 }
+
+/**
+ * A description of a class of fixes. Instances are intended to hold the
+ * information that is common across a number of fixes and to be shared by those
+ * fixes. For example, if an unnecessary cast is found then one of the suggested
+ * fixes will be to remove the cast. If there are multiple unnecessary casts in
+ * a single file, then there will be multiple fixes, one per occurrence, but
+ * they will all share the same kind.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+class FixKind {
+  /**
+   * The name of this kind of fix, used for debugging.
+   */
+  final String name;
+
+  /**
+   * The priority of this kind of fix for the kind of error being addressed.
+   */
+  final int priority;
+
+  /**
+   * A human-readable description of the changes that will be applied by this
+   * kind of fix. The message can contain parameters, where each parameter is
+   * represented by a zero-based index inside curly braces. For example, the
+   * message `"Create a component named '{0}' in '{1}'"` contains two parameters.
+   */
+  final String message;
+
+  /**
+   * Initialize a newly created kind of fix to have the given [name],
+   * [priority] and [message].
+   */
+  const FixKind(this.name, this.priority, this.message);
+
+  @override
+  String toString() => name;
+}