Expose aggregate transformers in pub.

dart/sdk/lib/_internal/pub/lib/src/barback/excluding_aggregate_transformer.dart

Index: dart/sdk/lib/_internal/pub/lib/src/barback/excluding_aggregate_transformer.dart
diff --git a/dart/sdk/lib/_internal/pub/lib/src/barback/excluding_aggregate_transformer.dart b/dart/sdk/lib/_internal/pub/lib/src/barback/excluding_aggregate_transformer.dart
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+++ b/dart/sdk/lib/_internal/pub/lib/src/barback/excluding_aggregate_transformer.dart
@@ -0,0 +1,85 @@
+// 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 pub.excluding_aggregate_transformer;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+/// Decorates an inner [AggregateTransformer] and handles including and
+/// excluding primary inputs.
+class ExcludingAggregateTransformer extends AggregateTransformer {
+  /// If [includes] or [excludes] is non-null, wraps [inner] in an
+  /// [ExcludingAggregateTransformer] that handles those.
+  ///
+  /// Otherwise, just returns [inner] unmodified.
+  static AggregateTransformer wrap(AggregateTransformer inner,
+      Set<String> includes, Set<String> excludes) {
+    if (includes == null && excludes == null) return inner;
+
+    if (inner is LazyAggregateTransformer) {
+      return new _LazyExcludingAggregateTransformer(
+          inner as LazyAggregateTransformer, includes, excludes);
+    } else if (inner is DeclaringAggregateTransformer) {
+      return new _DeclaringExcludingAggregateTransformer(
+          inner as DeclaringAggregateTransformer, includes, excludes);
+    } else {
+      return new ExcludingAggregateTransformer._(inner, includes, excludes);
+    }
+  }
+
+  final AggregateTransformer _inner;
+
+  /// The set of asset paths which should be included.
+  ///
+  /// If `null`, all non-excluded assets are allowed. Otherwise, only included
+  /// assets are allowed.
+  final Set<String> _includes;
+
+  /// The set of assets which should be excluded.
+  ///
+  /// Exclusions are applied after inclusions.
+  final Set<String> _excludes;
+
+  ExcludingAggregateTransformer._(this._inner, this._includes, this._excludes);
+
+  classifyPrimary(AssetId id) {
+    // TODO(rnystrom): Support globs in addition to paths. See #17093.
+    if (_includes != null) {
+      // If there are any includes, it must match one of them.
+      if (!_includes.contains(id.path)) return null;
+    }
+
+    // It must not be excluded.
+    if (_excludes != null && _excludes.contains(id.path)) {
+      return null;
+    }
+
+    return _inner.classifyPrimary(id);
+  }
+
+  Future apply(AggregateTransform transform) => _inner.apply(transform);
+
+  String toString() => _inner.toString();
+}
+
+class _DeclaringExcludingAggregateTransformer
+    extends ExcludingAggregateTransformer
+    implements DeclaringAggregateTransformer {
+  _DeclaringExcludingAggregateTransformer(DeclaringAggregateTransformer inner,
+        Set<String> includes, Set<String> excludes)
+      : super._(inner as AggregateTransformer, includes, excludes);
+
+  Future declareOutputs(DeclaringAggregateTransform transform) =>
+      (_inner as DeclaringAggregateTransformer).declareOutputs(transform);
+}
+
+class _LazyExcludingAggregateTransformer
+    extends _DeclaringExcludingAggregateTransformer
+    implements LazyAggregateTransformer {
+  _LazyExcludingAggregateTransformer(DeclaringAggregateTransformer inner,
+        Set<String> includes, Set<String> excludes)
+      : super(inner, includes, excludes);
+}