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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.transform; | |
| 6 | |
| 7 import 'dart:async'; | |
| 8 import 'dart:convert'; | |
| 9 | |
| 10 import 'asset.dart'; | |
| 11 import 'asset_id.dart'; | |
| 12 import 'asset_set.dart'; | |
| 13 import 'base_transform.dart'; | |
| 14 import 'errors.dart'; | |
| 15 import 'transform_node.dart'; | |
| 16 import 'utils.dart'; | |
| 17 | |
| 18 /// While a [Transformer] represents a *kind* of transformation, this defines | |
| 19 /// one specific usage of it on a set of files. | |
| 20 /// | |
| 21 /// This ephemeral object exists only during an actual transform application to | |
| 22 /// facilitate communication between the [Transformer] and the code hosting | |
| 23 /// the transformation. It lets the [Transformer] access inputs and generate | |
| 24 /// outputs. | |
| 25 class Transform extends BaseTransform { | |
| 26 final TransformNode _node; | |
| 27 | |
| 28 final _outputs = new AssetSet(); | |
| 29 | |
| 30 /// Gets the primary input asset. | |
| 31 /// | |
| 32 /// While a transformation can use multiple input assets, one must be a | |
| 33 /// special "primary" asset. This will be the "entrypoint" or "main" input | |
| 34 /// file for a transformation. | |
| 35 /// | |
| 36 /// For example, with a dart2js transform, the primary input would be the | |
| 37 /// entrypoint Dart file. All of the other Dart files that that imports | |
| 38 /// would be secondary inputs. | |
| 39 /// | |
| 40 /// This method may fail at runtime with an [AssetNotFoundException] if called | |
| 41 /// asynchronously after the transform begins running. The primary input may | |
| 42 /// become unavailable while this transformer is running due to asset changes | |
| 43 /// earlier in the graph. You can ignore the error if this happens: the | |
| 44 /// transformer will be re-run automatically for you. | |
| 45 Asset get primaryInput { | |
| 46 if (!_node.primary.state.isAvailable) { | |
| 47 throw new AssetNotFoundException(_node.primary.id); | |
| 48 } | |
| 49 | |
| 50 return _node.primary.asset; | |
| 51 } | |
| 52 | |
| 53 Transform._(TransformNode node) | |
| 54 : _node = node, | |
| 55 super(node); | |
| 56 | |
| 57 /// Gets the asset for an input [id]. | |
| 58 /// | |
| 59 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 60 Future<Asset> getInput(AssetId id) { | |
| 61 if (id == _node.primary.id) return syncFuture(() => primaryInput); | |
| 62 return _node.getInput(id); | |
| 63 } | |
| 64 | |
| 65 /// A convenience method to the contents of the input with [id] as a string. | |
| 66 /// | |
| 67 /// This is equivalent to calling [getInput] followed by [Asset.readAsString]. | |
| 68 /// | |
| 69 /// If the asset was created from a [String] the original string is always | |
| 70 /// returned and [encoding] is ignored. Otherwise, the binary data of the | |
| 71 /// asset is decoded using [encoding], which defaults to [UTF8]. | |
| 72 /// | |
| 73 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 74 Future<String> readInputAsString(AssetId id, {Encoding encoding}) { | |
| 75 if (encoding == null) encoding = UTF8; | |
| 76 return getInput(id).then((input) => input.readAsString(encoding: encoding)); | |
| 77 } | |
| 78 | |
| 79 /// A convenience method to the contents of the input with [id]. | |
| 80 /// | |
| 81 /// This is equivalent to calling [getInput] followed by [Asset.read]. | |
| 82 /// | |
| 83 /// If the asset was created from a [String], this returns its UTF-8 encoding. | |
| 84 /// | |
| 85 /// If an input with [id] cannot be found, throws an [AssetNotFoundException]. | |
| 86 Stream<List<int>> readInput(AssetId id) => | |
| 87 futureStream(getInput(id).then((input) => input.read())); | |
| 88 | |
| 89 /// A convenience method to return whether or not an asset exists. | |
| 90 /// | |
| 91 /// This is equivalent to calling [getInput] and catching an | |
| 92 /// [AssetNotFoundException]. | |
| 93 Future<bool> hasInput(AssetId id) { | |
| 94 return getInput(id).then((_) => true).catchError((error) { | |
| 95 if (error is AssetNotFoundException && error.id == id) return false; | |
| 96 throw error; | |
| 97 }); | |
| 98 } | |
| 99 | |
| 100 /// Stores [output] as the output created by this transformation. | |
| 101 /// | |
| 102 /// A transformation can output as many assets as it wants. | |
| 103 void addOutput(Asset output) { | |
| 104 // TODO(rnystrom): This should immediately throw if an output with that ID | |
| 105 // has already been created by this transformer. | |
| 106 _outputs.add(output); | |
| 107 } | |
| 108 } | |
| 109 | |
| 110 /// The controller for [Transform]. | |
| 111 class TransformController extends BaseTransformController { | |
| 112 Transform get transform => super.transform; | |
| 113 | |
| 114 /// The set of assets that the transformer has emitted. | |
| 115 AssetSet get outputs => transform._outputs; | |
| 116 | |
| 117 TransformController(TransformNode node) | |
| 118 : super(new Transform._(node)); | |
| 119 } | |
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Chromium Code Reviews
Issue 261823008:
Reorganize barback's source files. (Closed)
Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart