fix(transformers): Fix relative URL lookup for transformers, and web

Extracts logic used in the TypeRelativeUriGenerator to be used in other
transformers. This allows other transformers such as the ExpressionGenerator
and later the TemplateCacheGenerator to find relative resources.

Fixes asset resolution according to Barback rules which are defined here:
http://goo.gl/YDMRc2 specifically library assets are defined with packages
being in the URI and all other resources are considered web resources.

Closes #1649, #1651

lib/tools/transformer/referenced_uris.dart

@@ -4,6 +4,7 @@ import 'dart:async';
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
+import 'package:angular/tools/transformer/transformer_resource_url_resolver.dart';
 import 'package:angular/tools/transformer/options.dart';
 import 'package:barback/barback.dart';
 import 'package:code_transformers/resolver.dart';
@@ -15,8 +16,10 @@ import 'package:path/path.dart' as path;
 Future<Map<String, String>> gatherReferencedUris(Transform transform,
     Resolver resolver, TransformOptions options,
     {bool skipNonCached: false, bool templatesOnly: false}) {
+  var urlResolver =
+      new TransformerResourceUrlResolver(resolver, transform.primaryInput.id);
   return new _Processor(transform, resolver, options, skipNonCached,
-      templatesOnly).process();
+      templatesOnly, urlResolver).process();
 }
 
 class _Processor {
@@ -26,6 +29,7 @@ class _Processor {
   final Map<RegExp, String> templateUriRewrites = <RegExp, String>{};
   final bool skipNonCached;
   final bool templatesOnly;
+  final TransformerResourceUrlResolver urlResolver;
 
   ConstructorElement cacheAnnotation;
   ConstructorElement componentAnnotation;
@@ -35,7 +39,7 @@ class _Processor {
   static const String componentAnnotationName = 'angular.core.annotation_src.Component';
 
   _Processor(this.transform, this.resolver, this.options, this.skipNonCached,
-      this.templatesOnly) {
+      this.templatesOnly, this.urlResolver) {
     for (var key in options.templateUriRewrites.keys) {
       templateUriRewrites[new RegExp(key)] = options.templateUriRewrites[key];
     }
@@ -199,6 +203,7 @@ class _Processor {
 
   _CacheEntry uriToEntry(String uri, Element reference) {
     uri = rewriteUri(uri);
+    uri = urlResolver.combineWithElement(reference, uri);
     if (Uri.parse(uri).scheme != '') {
       warn('Cannot cache non-local URIs. $uri', reference);
       return null;
@@ -212,7 +217,10 @@ class _Processor {
       warn('Cannot cache non-package absolute URIs. $uri', reference);
       return null;
     }
-    var assetId = new AssetId(transform.primaryInput.id.package, uri);
+    // Everything else is a resource in the web directory according to pub;
+    // as all packages URIs were handled above. As specified in this
+    // [Barback Doc](http://goo.gl/YDMRc2)
+    var assetId = new AssetId(transform.primaryInput.id.package, 'web/$uri');
     return new _CacheEntry(uri, reference, assetId);
   }
 

lib/tools/transformer/transformer_resource_url_resolver.dart

@@ -0,0 +1,62 @@
+library angular.tools.transformer.angular_file_resolver;
+
+import 'package:analyzer/src/generated/element.dart';
+import 'package:code_transformers/resolver.dart';
+import 'package:barback/barback.dart';
+
+/// Resolver used to find absolute resources when in Transformers by combining
+/// AST element locations and relative URIs.
+class TransformerResourceUrlResolver {
+  final Resolver _resolver;
+  final AssetId _primaryAsset;
+
+  TransformerResourceUrlResolver(this._resolver, this._primaryAsset);
+
+  Uri findUriOfElement(Element type) {
+    var uri = _resolver.getImportUri(type.library, from: _primaryAsset);
+    var acceptable = (
+        (uri.isAbsolute && uri.scheme == 'package') ||
+        (uri.toString() == uri.path));
+    if (!acceptable) {
+      var errMsg = 'ERROR: Type "$type" has unsupported URI $uri';
+      throw errMsg;
+    }
+    if (uri.scheme != "package") {
+      // this is guaranteed to be a relative URL (e.g. type defined in a path
+      // imported file)
+      var path = _primaryAsset.path;
+      if (!path.startsWith('web/')) {
+        var errMsg = 'ERROR: Type "$type" is imported as a path not under web.';
+        throw errMsg;
+      }
+      uri = Uri.parse(path.substring('web/'.length)).resolve(uri.path);
+    }
+    return uri;
+  }
+
+  /// Given a AST [type] and [uri] if [uri] is relative combines it with the uri
+  /// of the element to make an absolute location relative to types uri.
+  /// Note: This logic should match [ResourceUrlResolver], but is separate as
+  /// transformers and Mirrors have different APIs to identify elements, and
+  /// calculate their URIs.
+  String combineWithElement(Element type, String uri) {
+    if (uri != null) {
+      if (uri.startsWith("/")) return uri;
+      if (uri.startsWith("packages/")) return "/" + uri;
+    }
+
+    var typeUri = findUriOfElement(type);
+
+    if (uri == null) {
+      uri = typeUri.path;
+    }
+    // If it's not absolute, then resolve it first
+    Uri resolved = typeUri.resolve(uri);
+
+    if (resolved.scheme == 'package') {
+      return '/packages/${resolved.path}';
+    } else {
+      return resolved.toString();
+    }
+  }
+}

lib/tools/transformer/type_relative_uri_generator.dart

@@ -4,6 +4,7 @@ import 'dart:async';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:angular/tools/transformer/options.dart';
+import 'package:angular/tools/transformer/transformer_resource_url_resolver.dart';
 import 'package:barback/barback.dart';
 import 'package:code_transformers/resolver.dart';
 import 'package:path/path.dart' as path;
@@ -36,6 +37,7 @@ class TypeRelativeUriGenerator extends Transformer with ResolverTransformer {
       transform.logger.warning('Unable to resolve $componentAnnotationName.');
     }
 
+    var urlResolver = new TransformerResourceUrlResolver(resolver, id);
     var annotatedTypes = resolver.libraries
         .expand((lib) => lib.units)
         .expand((unit) => unit.types)
@@ -69,28 +71,7 @@ class TypeRelativeUriGenerator extends Transformer with ResolverTransformer {
     for (var type in annotatedTypes) {
       outputBuffer.write('  ${importPrefixes[type.library]}${type.name}: ');
 
-      var uri = resolver.getImportUri(type.library,
-                                      from: transform.primaryInput.id);
-
-      var acceptable = (
-          (uri.isAbsolute && uri.scheme == "package") ||
-          (uri.toString() == uri.path));
-      if (!acceptable) {
-        var errMsg = 'ERROR: $runtimeType: Type "$type" has unsupported URI $uri';
-        transform.logger.error(errMsg);
-        throw errMsg;
-      }
-      if (uri.scheme != "package") {
-        // this is guaranteed to be a relative URL (e.g. type defined in a path
-        // imported file)
-        var path = transform.primaryInput.id.path;
-        if (!path.startsWith("web/")) {
-          var errMsg = 'ERROR: $runtimeType: Type "$type" is imported as a path not under web.';
-          transform.logger.error(errMsg);
-          throw errMsg;
-        }
-        uri = Uri.parse(path.substring("web/".length)).resolve(uri.path);
-      }
+      var uri = urlResolver.findUriOfElement(type);
       outputBuffer.write("Uri.parse(r'''$uri'''),\n");
     }
     _writeFooter(outputBuffer);

test/tools/transformer/expression_generator_spec.dart

@@ -68,7 +68,7 @@ main() {
                 import 'package:angular/angular.dart';
 
                 @Component(
-                    templateUrl: 'lib/foo.html',
+                    templateUrl: 'foo.html',
                     selector: 'my-component')
                 class FooComponent {}
 
@@ -79,7 +79,7 @@ main() {
 
                 main() {}
                 ''',
-            'a|lib/foo.html': '''
+            'a|web/foo.html': '''
                 <div>{{template.contents}}</div>''',
             'b|lib/bar.html': '''
                 <div>{{bar}}</div>''',
@@ -119,14 +119,41 @@ main() {
           symbols: []);
     });
 
+    it('should respect relative URLs', () {
+      return generates(phases,
+          inputs: {
+            'a|web/main.dart': '''
+                import 'package:b/bar.dart';
+
+                main() {}
+                ''',
+            'b|lib/bar.dart': '''
+                import 'package:angular/angular.dart';
+
+                @Component(
+                    templateUrl: 'bar.html',
+                    selector: 'my-component')
+                class BarComponent {}
+                ''',
+            'b|lib/bar.html': '''
+                <div>{{bar}}</div>''',
+            'a|web/index.html': '''
+                <script src='main.dart' type='application/dart'></script>''',
+            'angular|lib/angular.dart': libAngular,
+          },
+          getters: ['bar'],
+          setters: ['bar'],
+      symbols: []);
+    });
+
     it('should generate expressions for variables found in superclass', () {
       return generates(phases,
       inputs: {
           'a|web/main.dart': '''
                 import 'package:angular/angular.dart';
 
                 @Component(
-                    templateUrl: 'lib/foo.html',
+                    templateUrl: 'foo.html',
                     selector: 'my-component')
                 class FooComponent extends BarComponent {
                   @NgAttr('foo')
@@ -140,7 +167,7 @@ main() {
 
                 main() {}
                 ''',
-          'a|lib/foo.html': '''
+          'a|web/foo.html': '''
                 <div>{{template.foo}}</div>
                 <div>{{template.bar}}</div>''',
           'a|web/index.html': '''