Updating code_transformer's ResolverTransform to filter on Dart entry points in apply.

pkg/code_transformers/lib/src/resolvers.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_transformers.src.resolvers;
 
 import 'dart:async';
-import 'package:barback/barback.dart' show AssetId, Transformer, Transform;
+import 'package:barback/barback.dart';
 
+import 'entry_point.dart';
 import 'resolver.dart';
 import 'resolver_impl.dart';
 
 /// Barback-based code resolvers which maintains up-to-date resolved ASTs for
 /// the specified code entry points.
 ///
 /// This can used by transformers dependent on resolved ASTs to handle the
 /// resolution of the AST and cache the results between compilations.
 ///
 /// If multiple transformers rely on a resolved AST they should (ideally) share
@@ skipping 20 matching lines @@
 }
 
 /// Transformer mixin which automatically gets and releases resolvers.
 ///
 /// To use mix this class in, set the resolvers field and override
 /// [applyResolver].
 abstract class ResolverTransformer implements Transformer {
   /// The cache of resolvers- must be set from subclass.
   Resolvers resolvers;
 
+  /// By default only process prossible entry point assets.
+  ///
+  /// This is only a preliminary check based on the asset ID.
+  Future<bool> isPrimary(assetOrId) {
+    // assetOrId is to handle the transition from Asset to AssetID between
+    // pub 1.3 and 1.4. Once support for 1.3 is dropped this should only
+    // support AssetId.
+    var id = assetOrId is AssetId ? assetOrId : assetOrId.id;
+    return new Future.value(isPossibleDartEntryId(id));
+  }
+
+  /// Check to see if this should apply with the resolver on the provided asset.
+  ///
+  /// By default this will only apply on possible Dart entry points (see
+  /// [isPossibleDartEntry]).
+  Future<bool> shouldApplyResolver(Asset asset) => isPossibleDartEntry(asset);
+
+
   /// This provides a default implementation of `Transformer.apply` that will
   /// get and release resolvers automatically. Internally this:
   ///   * Gets a resolver associated with the transform primary input.
   ///   * Does resolution to the code starting from that input.
   ///   * Calls [applyResolver].
   ///   * Then releases the resolver.
   ///
   /// Use [applyToEntryPoints] instead if you need to override the entry points
   /// to run the resolver on.
-  Future apply(Transform transform) => applyToEntryPoints(transform);
+  Future apply(Transform transform) =>
+      shouldApplyResolver(transform.primaryInput).then((result) {
+        if (result) return applyToEntryPoints(transform);
+      });
+
 
   /// Helper function to make it easy to write an `Transformer.apply` method
   /// that automatically gets and releases the resolver. This is typically used
   /// as follows:
   ///
   ///    Future apply(Transform transform) {
   ///       var entryPoints = ...; // compute entry points
   ///       return applyToEntryPoints(transform, entryPoints);
   ///    }
   Future applyToEntryPoints(Transform transform, [List<AssetId> entryPoints]) {
     return resolvers.get(transform, entryPoints).then((resolver) {
       return new Future(() => applyResolver(transform, resolver))
         .whenComplete(() {
           resolver.release();
         });
     });
   }
 
   /// Invoked when the resolver is ready to be processed.
   ///
   /// Return a Future to indicate when apply is completed.
   applyResolver(Transform transform, Resolver resolver);
 }