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| 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 library barback.transformer.transform; | |
| 6 | |
| 7 import 'dart:async'; | |
| 8 import 'dart:convert'; | |
| 9 | |
| 10 import '../asset/asset.dart'; | |
| 11 import '../asset/asset_id.dart'; | |
| 12 import '../errors.dart'; | |
| 13 import 'aggregate_transform.dart'; | |
| 14 import 'transform_logger.dart'; | |
| 15 | |
| 16 /// Creates a new [Transform] wrapping an [AggregateTransform]. | |
| 17 /// | |
| 18 /// Although barback internally works in terms of [AggregateTransformer]s, most | |
| 19 /// transformers only work on individual primary inputs in isolation. We want to | |
| 20 /// allow those transformers to implement the more user-friendly [Transformer] | |
| 21 /// interface which takes the more user-friendly [Transform] object. This method | |
| 22 /// wraps the more general [AggregateTransform] to return a [Transform] instead. | |
| 23 Future<Transform> newTransform(AggregateTransform aggregate) { | |
| 24 // A wrapped [Transformer] will assign each primary input a unique transform | |
| 25 // key, so we can safely get the first asset emitted. We don't want to wait | |
| 26 // for the stream to close, since that requires barback to prove that no more | |
| 27 // new assets will be generated. | |
| 28 return aggregate.primaryInputs.first.then((primaryInput) => | |
| 29 new Transform._(aggregate, primaryInput)); | |
| 30 } | |
| 31 | |
| 32 /// While a [Transformer] represents a *kind* of transformation, this defines | |
| 33 /// one specific usage of it on a set of files. | |
| 34 /// | |
| 35 /// This ephemeral object exists only during an actual transform application to | |
| 36 /// facilitate communication between the [Transformer] and the code hosting | |
| 37 /// the transformation. It lets the [Transformer] access inputs and generate | |
| 38 /// outputs. | |
| 39 class Transform { | |
| 40 /// The underlying aggregate transform. | |
| 41 final AggregateTransform _aggregate; | |
| 42 | |
| 43 /// Gets the primary input asset. | |
| 44 /// | |
| 45 /// While a transformation can use multiple input assets, one must be a | |
| 46 /// special "primary" asset. This will be the "entrypoint" or "main" input | |
| 47 /// file for a transformation. | |
| 48 /// | |
| 49 /// For example, with a dart2js transform, the primary input would be the | |
| 50 /// entrypoint Dart file. All of the other Dart files that that imports | |
| 51 /// would be secondary inputs. | |
| 52 final Asset primaryInput; | |
| 53 | |
| 54 /// A logger so that the [Transformer] can report build details. | |
| 55 TransformLogger get logger => _aggregate.logger; | |
| 56 | |
| 57 Transform._(this._aggregate, this.primaryInput); | |
| 58 | |
| 59 /// Gets the asset for an input [id]. | |
| 60 /// | |
| 61 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 62 Future<Asset> getInput(AssetId id) => _aggregate.getInput(id); | |
| 63 | |
| 64 /// A convenience method to the contents of the input with [id] as a string. | |
| 65 /// | |
| 66 /// This is equivalent to calling [getInput] followed by [Asset.readAsString]. | |
| 67 /// | |
| 68 /// If the asset was created from a [String] the original string is always | |
| 69 /// returned and [encoding] is ignored. Otherwise, the binary data of the | |
| 70 /// asset is decoded using [encoding], which defaults to [UTF8]. | |
| 71 /// | |
| 72 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 73 Future<String> readInputAsString(AssetId id, {Encoding encoding}) => | |
| 74 _aggregate.readInputAsString(id, encoding: encoding); | |
| 75 | |
| 76 /// A convenience method to the contents of the input with [id]. | |
| 77 /// | |
| 78 /// This is equivalent to calling [getInput] followed by [Asset.read]. | |
| 79 /// | |
| 80 /// If the asset was created from a [String], this returns its UTF-8 encoding. | |
| 81 /// | |
| 82 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 83 Stream<List<int>> readInput(AssetId id) => _aggregate.readInput(id); | |
| 84 | |
| 85 /// A convenience method to return whether or not an asset exists. | |
| 86 /// | |
| 87 /// This is equivalent to calling [getInput] and catching an | |
| 88 /// [AssetNotFoundException]. | |
| 89 Future<bool> hasInput(AssetId id) => _aggregate.hasInput(id); | |
| 90 | |
| 91 /// Stores [output] as the output created by this transformation. | |
| 92 /// | |
| 93 /// A transformation can output as many assets as it wants. | |
| 94 void addOutput(Asset output) => _aggregate.addOutput(output); | |
| 95 | |
| 96 /// Consume the primary input so that it doesn't get processed by future | |
| 97 /// phases or emitted once processing has finished. | |
| 98 /// | |
| 99 /// Normally the primary input will automatically be forwarded unless the | |
| 100 /// transformer overwrites it by emitting an input with the same id. This | |
| 101 /// allows the transformer to tell barback not to forward the primary input | |
| 102 /// even if it's not overwritten. | |
| 103 void consumePrimary() => _aggregate.consumePrimary(primaryInput.id); | |
| 104 } | |
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Chromium Code Reviews
Issue 808713003:
Remove barback from the repo. (Closed)
Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart