pkg/barback/lib/src/transformer/base_transform.dart - Issue 808713003: Remove barback from the repo.

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Issue 808713003: Remove barback from the repo. (Closed) Base URL: https://dart.googlecode.com/svn/branches/bleeding_edge/dart

Patch Set: Created 6 years ago

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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.base_transform;

6

7 import 'dart:async';

8

9 import '../asset/asset_id.dart';

10 import '../graph/transform_node.dart';

11 import '../log.dart';

12 import 'transform_logger.dart';

13

14 /// The base class for the ephemeral transform objects that are passed to

15 /// transformers.

16 ///

17 /// This class provides the transformers with inputs, but its up to the

18 /// subclasses to provide a means of emitting outputs.

19 abstract class BaseTransform {

20 final TransformNode _node;

21

22 /// The ids of primary inputs that should be consumed.

23 ///

24 /// This is exposed by [BaseTransformController].

25 final _consumedPrimaries = new Set<AssetId>();

26

27 /// Whether the transformer logged an error.

28 ///

29 /// This is exposed via [BaseTransformController].

30 bool _loggedError = false;

31

32 /// The controller for the stream of log entries emitted by the transformer.

33 ///

34 /// This is exposed via [BaseTransformController].

35 ///

36 /// This is synchronous because error logs can cause the transform to fail, so

37 /// we need to ensure that their processing isn't delayed until after the

38 /// transform or build has finished.

39 final _onLogController = new StreamController<LogEntry>.broadcast(sync: true);

40

41 /// A logger so that the [Transformer] can report build details.

42 TransformLogger get logger => _logger;

43 TransformLogger _logger;

44

45 BaseTransform(this._node) {

46 _logger = new TransformLogger((asset, level, message, span) {

47 if (level == LogLevel.ERROR) _loggedError = true;

48

49 // If the log isn't already associated with an asset, use the primary.

50 if (asset == null) asset = _node.info.primaryId;

51 var entry = new LogEntry(_node.info, asset, level, message, span);

52

53 // The log controller can be closed while log entries are still coming in

54 // if the transformer is removed during [apply].

55 if (!_onLogController.isClosed) _onLogController.add(entry);

56 });

57 }

58

59 /// Consume a primary input so that it doesn't get processed by future

60 /// phases or emitted once processing has finished.

61 ///

62 /// Normally each primary input will automatically be forwarded unless the

63 /// transformer overwrites it by emitting an input with the same id. This

64 /// allows the transformer to tell barback not to forward a primary input

65 /// even if it's not overwritten.

66 void consumePrimary(AssetId id) {

67 // TODO(nweiz): throw an error if an id is consumed that wasn't listed as a

68 // primary input.

69 _consumedPrimaries.add(id);

70 }

71 }

72

73 /// The base class for controllers of subclasses of [BaseTransform].

74 ///

75 /// Controllers are used so that [TransformNode]s can get values from a

76 /// [BaseTransform] without exposing getters in the public API.

77 abstract class BaseTransformController {

78 /// The [BaseTransform] controlled by this controller.

79 final BaseTransform transform;

80

81 /// The ids of primary inputs that should be consumed.

82 Set<AssetId> get consumedPrimaries => transform._consumedPrimaries;

83

84 /// Whether the transform logged an error.

85 bool get loggedError => transform._loggedError;

86

87 /// The stream of log entries emitted by the transformer during a run.

88 Stream<LogEntry> get onLog => transform._onLogController.stream;

89

90 /// Whether the transform's input or id stream has been closed.

91 ///

92 /// See also [done].

93 bool get isDone;

94

95 BaseTransformController(this.transform);

96

97 /// Mark this transform as finished emitting new inputs or input ids.

98 ///

99 /// This is distinct from [cancel] in that it doesn't indicate that the

100 /// transform is finished being used entirely. The transformer may still log

101 /// messages and load secondary inputs. This just indicates that all the

102 /// primary inputs are accounted for.

103 void done();

104

105 /// Mark this transform as canceled.

106 ///

107 /// This will close any streams and release any resources that were allocated

108 /// for the duration of the transformation. Unlike [done], this indicates that

109 /// the transformation is no longer relevant; either it has returned, or

110 /// something external has preemptively invalidated its results.

111 void cancel() {

112 done();

113 transform._onLogController.close();

114 }

115 }

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