Adding some asset-related utilities to code_transformers

pkg/code_transformers/lib/src/resolver_impl.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.
 
 library code_transformer.src.resolver_impl;
 
 import 'dart:async';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/sdk.dart' show DartSdk;
 import 'package:analyzer/src/generated/sdk_io.dart' show DirectoryBasedDartSdk;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:barback/barback.dart';
 import 'package:path/path.dart' as native_path;
 import 'package:source_maps/refactor.dart';
 import 'package:source_maps/span.dart' show SourceFile, Span;
 
+import 'assets.dart';
 import 'resolver.dart';
 
 // We should always be using url paths here since it's always Dart/pub code.
 final path = native_path.url;
 
 /// Resolves and updates an AST based on Barback-based assets.
 ///
 /// This also provides a handful of useful APIs for traversing and working
 /// with the resolved AST.
 class ResolverImpl implements Resolver {
@@ skipping 472 matching lines @@
 
   if (uri.scheme == 'package') {
     var segments = new List.from(uri.pathSegments);
     var package = segments[0];
     segments[0] = 'lib';
     return new AssetId(package, segments.join(path.separator));
   }
   // Dart SDK libraries do not have assets.
   if (uri.scheme == 'dart') return null;
 
-  if (uri.host != '' || uri.scheme != '' || path.isAbsolute(url)) {
-    logger.error('absolute paths not allowed: "$url"', span: span);
-    return null;
-  }
-
-  var targetPath = path.normalize(
-      path.join(path.dirname(source.path), url));
-  return new AssetId(source.package, targetPath);
+  return uriToAssetId(source, url, logger, span);
 }
 
 
 /// A completer that waits until all added [Future]s complete.
 // TODO(blois): Copied from quiver. Remove from here when it gets
 // added to dart:core. (See #6626.)
 class FutureGroup<E> {
   static const _FINISHED = -1;
 
   int _pending = 0;
@@ skipping 37 matching lines @@
 
   /**
    * A Future that complets with a List of the values from all the added
    * tasks, when they have all completed.
    *
    * If any task fails, this Future will receive the error. Only the first
    * error will be sent to the Future.
    */
   Future<List<E>> get future => _completer.future;
 }