| // 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 barback.transformer.aggregate_transform; |
| |
| import 'dart:async'; |
| import 'dart:convert'; |
| |
| import '../asset/asset.dart'; |
| import '../asset/asset_id.dart'; |
| import '../asset/asset_set.dart'; |
| import '../errors.dart'; |
| import '../graph/transform_node.dart'; |
| import '../utils.dart'; |
| import 'base_transform.dart'; |
| |
| /// A transform for [AggregateTransformer]s that provides access to all of their |
| /// primary inputs. |
| class AggregateTransform extends BaseTransform { |
| final TransformNode _node; |
| |
| /// The set of outputs emitted by the transformer. |
| final _outputs = new AssetSet(); |
| |
| /// The transform key. |
| /// |
| /// This is the key returned by [AggregateTransformer.classifyPrimary] for all |
| /// the assets in this transform. |
| String get key => _node.key; |
| |
| /// The package in which this transform is running. |
| String get package => _node.phase.cascade.package; |
| |
| /// The stream of primary inputs that will be processed by this transform. |
| /// |
| /// This is exposed as a stream so that the transformer can start working |
| /// before all its inputs are available. The stream is closed not just when |
| /// all inputs are provided, but when barback is confident no more inputs will |
| /// be forthcoming. |
| /// |
| /// A transformer may complete its `apply` method before this stream is |
| /// closed. For example, it may know that each key will only have two inputs |
| /// associated with it, and so use `transform.primaryInputs.take(2)` to access |
| /// only those inputs. |
| Stream<Asset> get primaryInputs => _inputController.stream; |
| final _inputController = new StreamController<Asset>(); |
| |
| /// The set of all primary inputs that have been emitted by [primaryInputs]. |
| /// |
| /// This is populated by the transform's controller so that |
| /// [AggregateTransformController.addedId] synchronously returns the correct |
| /// result after [AggregateTransformController.addInput] is called. |
| final _emittedPrimaryInputs = new AssetSet(); |
| |
| AggregateTransform._(TransformNode node) |
| : _node = node, |
| super(node); |
| |
| /// Gets the asset for an input [id]. |
| /// |
| /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. |
| Future<Asset> getInput(AssetId id) { |
| if (_emittedPrimaryInputs.containsId(id)) { |
| return syncFuture(() => _emittedPrimaryInputs[id]); |
| } else { |
| return _node.getInput(id); |
| } |
| } |
| |
| /// A convenience method to the contents of the input with [id] as a string. |
| /// |
| /// This is equivalent to calling [getInput] followed by [Asset.readAsString]. |
| /// |
| /// If the asset was created from a [String] the original string is always |
| /// returned and [encoding] is ignored. Otherwise, the binary data of the |
| /// asset is decoded using [encoding], which defaults to [UTF8]. |
| /// |
| /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. |
| Future<String> readInputAsString(AssetId id, {Encoding encoding}) { |
| if (encoding == null) encoding = UTF8; |
| return getInput(id).then((input) => input.readAsString(encoding: encoding)); |
| } |
| |
| /// A convenience method to the contents of the input with [id]. |
| /// |
| /// This is equivalent to calling [getInput] followed by [Asset.read]. |
| /// |
| /// If the asset was created from a [String], this returns its UTF-8 encoding. |
| /// |
| /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. |
| Stream<List<int>> readInput(AssetId id) => |
| futureStream(getInput(id).then((input) => input.read())); |
| |
| /// A convenience method to return whether or not an asset exists. |
| /// |
| /// This is equivalent to calling [getInput] and catching an |
| /// [AssetNotFoundException]. |
| Future<bool> hasInput(AssetId id) { |
| return getInput(id).then((_) => true).catchError((error) { |
| if (error is AssetNotFoundException && error.id == id) return false; |
| throw error; |
| }); |
| } |
| |
| /// Stores [output] as the output created by this transformation. |
| /// |
| /// A transformation can output as many assets as it wants. |
| void addOutput(Asset output) { |
| // TODO(rnystrom): This should immediately throw if an output with that ID |
| // has already been created by this transformer. |
| _outputs.add(output); |
| } |
| |
| void consumePrimary(AssetId id) { |
| if (!_emittedPrimaryInputs.containsId(id)) { |
| throw new StateError( |
| "$id can't be consumed because it's not a primary input."); |
| } |
| |
| super.consumePrimary(id); |
| } |
| } |
| |
| /// The controller for [AggregateTransform]. |
| class AggregateTransformController extends BaseTransformController { |
| AggregateTransform get transform => super.transform; |
| |
| /// The set of assets that the transformer has emitted. |
| AssetSet get outputs => transform._outputs; |
| |
| bool get isDone => transform._inputController.isClosed; |
| |
| AggregateTransformController(TransformNode node) |
| : super(new AggregateTransform._(node)); |
| |
| /// Adds a primary input asset to the [AggregateTransform.primaryInputs] |
| /// stream. |
| void addInput(Asset input) { |
| transform._emittedPrimaryInputs.add(input); |
| transform._inputController.add(input); |
| } |
| |
| /// Returns whether an input with the given [id] was added via [addInput]. |
| bool addedId(AssetId id) => |
| transform._emittedPrimaryInputs.containsId(id); |
| |
| void done() { |
| transform._inputController.close(); |
| } |
| } |