Adds a repeatable --url_mapping flag to dartanalyzer

pkg/analyzer/lib/src/generated/source.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 engine.source;
 
 import "dart:math" as math;
 import 'dart:collection';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/source/package_map_resolver.dart';
 import 'package:analyzer/task/model.dart';
 
 import 'engine.dart';
 import 'java_core.dart';
 import 'java_engine.dart';
+import 'java_io.dart' show JavaFile;
 import 'sdk.dart' show DartSdk;
+import 'source_io.dart' show FileBasedSource;
 
 /**
  * A function that is used to handle [ContentCache] entries.
  */
 typedef void ContentCacheVisitor(Source source, int stamp, String contents);
 
 /**
  * Instances of class `ContentCache` hold content used to override the default content of a
  * [Source].
  */
@@ skipping 127 matching lines @@
 
   /**
    * Return `true` if the given URI is a `dart:` URI.
    *
    * @param uri the URI being tested
    * @return `true` if the given URI is a `dart:` URI
    */
   static bool isDartUri(Uri uri) => DART_SCHEME == uri.scheme;
 }
 
+class CustomUriResolver extends UriResolver {
+  final Map<String, String> _urlMappings;
+
+  CustomUriResolver(this._urlMappings);
+
+  @override
+  Source resolveAbsolute(Uri uri) {
+    String mapping = _urlMappings[uri.toString()];
+    if (mapping == null) return null;
+
+    Uri fileUri = new Uri.file(mapping);
+    if (!fileUri.isAbsolute) return null;
+
+    JavaFile javaFile = new JavaFile.fromUri(fileUri);
+    return new FileBasedSource.con1(javaFile);
+  }
+}
+
 /**
  * Instances of the class `LineInfo` encapsulate information about line and column information
  * within a source file.
  */
 class LineInfo {
   /**
    * An array containing the offsets of the first character of each line in the source code.
    */
   final List<int> _lineStarts;
 
@@ skipping 805 matching lines @@
 
   /**
    * Return an absolute URI that represents the given source, or `null` if a valid URI cannot
    * be computed.
    *
    * @param source the source to get URI for
    * @return the absolute URI representing the given source
    */
   Uri restoreAbsolute(Source source) => null;
 }