Add support for fixes

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

+// 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/dart/analysis/results.dart';
+import 'package:analyzer/error/error.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer_plugin/protocol/protocol.dart';
+import 'package:analyzer_plugin/protocol/protocol_generated.dart';
+import 'package:analyzer_plugin/src/utilities/fixes/fixes.dart';
+import 'package:analyzer_plugin/utilities/generator.dart';
+
+/**
+ * An object that [FixContributor]s use to record fixes.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class FixCollector {
+  /**
+   * Record a new [change] (fix) associated with the given [error].
+   */
+  void addFix(AnalysisError error, PrioritizedSourceChange change);
+}
+
+/**
+ * An object used to produce fixes.
+ *
+ * Clients may implement this class when implementing plugins.
+ */
+abstract class FixContributor {
+  /**
+   * Contribute fixes for the location in the file specified by the given
+   * [request] into the given [collector].
+   */
+  void computeFixes(FixesRequest request, FixCollector collector);
+}
+
+/**
+ * The information about a requested set of fixes.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class FixesRequest {
+  /**
+   * The analysis error to be fixed, or `null` if the error has not been
+   * determined.
+   */
+  AnalysisError get error;
+
+  /**
+   * Return the offset within the source for which fixes are being requested.
+   */
+  int get offset;
+
+  /**
+   * Return the resource provider associated with this request.
+   */
+  ResourceProvider get resourceProvider;
+
+  /**
+   * The analysis result for the file in which the fixes are being requested.
+   */
+  ResolveResult get result;
+}
+
+/**
+ * A generator that will generate an 'edit.getFixes' response.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+class FixGenerator {
+  /**
+   * The contributors to be used to generate the fixes.
+   */
+  final List<FixContributor> contributors;
+
+  /**
+   * Initialize a newly created fix generator to use the given [contributors].
+   */
+  FixGenerator(this.contributors);
+
+  /**
+   * Create an 'edit.getFixes' response for the location in the file specified
+   * by the given [request]. If any of the contributors throws an exception,
+   * also create a non-fatal 'plugin.error' notification.
+   */
+  GeneratorResult generateFixesResponse(FixesRequest request) {
+    List<Notification> notifications = <Notification>[];
+    FixCollectorImpl collector = new FixCollectorImpl();
+    Iterable<AnalysisError> errors = _getErrors(request);
+    FixesRequestImpl requestImpl = request;
+    for (FixContributor contributor in contributors) {
+      try {
+        for (AnalysisError error in errors) {
+          requestImpl.error = error;
+          contributor.computeFixes(request, collector);
+        }
+      } catch (exception, stackTrace) {
+        notifications.add(new PluginErrorParams(
+                false, exception.toString(), stackTrace.toString())
+            .toNotification());
+      } finally {
+        requestImpl.error = null;
+      }
+    }
+    EditGetFixesResult result = new EditGetFixesResult(collector.fixes);
+    return new GeneratorResult(result, notifications);
+  }
+
+  Iterable<AnalysisError> _getErrors(FixesRequest request) {
+    int offset = request.offset;
+    LineInfo lineInfo = request.result.lineInfo;
+    int offsetLine = lineInfo.getLocation(offset).lineNumber;
+    return request.result.errors.where((AnalysisError error) {
+      int errorLine = lineInfo.getLocation(error.offset).lineNumber;
+      return errorLine == offsetLine;
+    });
+  }
+}