Initial work on refactorings.

pkg/analysis_services/lib/src/refactoring/refactoring.dart

+// Copyright (c) 2014, 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.
+
+// This code was auto-generated, is not intended to be edited, and is subject to
+// significant change. Please see the README file for more information.
+
+library services.src.refactoring;
+
+import 'package:analysis_services/correction/status.dart';
+import 'package:analysis_services/refactoring/progress_monitor.dart';
+import 'package:analysis_services/refactoring/refactoring.dart';
+import 'package:analysis_services/src/refactoring/progress_monitor.dart';
+
+
+/**
+ * Returns [pm] if not `null` or a new [NullProgressMonitor] instance.
+ */
+ProgressMonitor checkProgressMonitor(ProgressMonitor pm) {
+  if (pm != null) {
+    return pm;
+  }
+  return new NullProgressMonitor();
+}
+
+
+/**
+ * Abstract implementation of {@link Refactoring}.
+ */
+abstract class RefactoringImpl implements Refactoring {
+  @override
+  RefactoringStatus checkAllConditions(ProgressMonitor pm) {
+    pm = checkProgressMonitor(pm);
+    pm.beginTask("", 2);
+    RefactoringStatus result = new RefactoringStatus();
+    result.merge(checkInitialConditions(new SubProgressMonitor(pm, 1)));
+    if (!result.hasFatalError) {
+      if (pm.isCanceled) {
+        throw new OperationCanceledException();
+      }
+      result.merge(checkFinalConditions(new SubProgressMonitor(pm, 1)));
+    }
+    pm.done();
+    return result;
+  }
+}