Run pub tests against older versions of barback.

third_party/pkg/barback-0.13.0/lib/src/transform_node.dart

+// Copyright (c) 2013, 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.transform_node;
+
+import 'dart:async';
+
+import 'asset.dart';
+import 'asset_id.dart';
+import 'asset_node.dart';
+import 'declaring_transform.dart';
+import 'errors.dart';
+import 'lazy_transformer.dart';
+import 'log.dart';
+import 'phase.dart';
+import 'stream_pool.dart';
+import 'transform.dart';
+import 'transformer.dart';
+import 'utils.dart';
+
+/// Describes a transform on a set of assets and its relationship to the build
+/// dependency graph.
+///
+/// Keeps track of whether it's dirty and needs to be run and which assets it
+/// depends on.
+class TransformNode {
+  /// The [Phase] that this transform runs in.
+  final Phase phase;
+
+  /// The [Transformer] to apply to this node's inputs.
+  final Transformer transformer;
+
+  /// The node for the primary asset this transform depends on.
+  final AssetNode primary;
+
+  /// A string describing the location of [this] in the transformer graph.
+  final String _location;
+
+  /// The subscription to [primary]'s [AssetNode.onStateChange] stream.
+  StreamSubscription _primarySubscription;
+
+  /// The subscription to [phase]'s [Phase.onAsset] stream.
+  StreamSubscription<AssetNode> _phaseSubscription;
+
+  /// Whether [this] is dirty and still has more processing to do.
+  bool get isDirty => !_state.isDone;
+
+  /// Whether [transformer] is lazy and this transform has yet to be forced.
+  bool _isLazy;
+
+  /// The subscriptions to each input's [AssetNode.onStateChange] stream.
+  final _inputSubscriptions = new Map<AssetId, StreamSubscription>();
+
+  /// The controllers for the asset nodes emitted by this node.
+  final _outputControllers = new Map<AssetId, AssetNodeController>();
+
+  final _missingInputs = new Set<AssetId>();
+
+  /// The controller that's used to pass [primary] through [this] if it's not
+  /// consumed or overwritten.
+  ///
+  /// This needs an intervening controller to ensure that the output can be
+  /// marked dirty when determining whether [this] will consume or overwrite it,
+  /// and be marked removed if it does. [_passThroughController] will be null
+  /// if the asset is not being passed through.
+  AssetNodeController _passThroughController;
+
+  /// A stream that emits an event whenever [this] is no longer dirty.
+  ///
+  /// This is synchronous in order to guarantee that it will emit an event as
+  /// soon as [isDirty] flips from `true` to `false`.
+  Stream get onDone => _onDoneController.stream;
+  final _onDoneController = new StreamController.broadcast(sync: true);
+
+  /// A stream that emits any new assets emitted by [this].
+  ///
+  /// Assets are emitted synchronously to ensure that any changes are thoroughly
+  /// propagated as soon as they occur.
+  Stream<AssetNode> get onAsset => _onAssetController.stream;
+  final _onAssetController =
+      new StreamController<AssetNode>.broadcast(sync: true);
+
+  /// A stream that emits an event whenever this transform logs an entry.
+  ///
+  /// This is synchronous because error logs can cause the transform to fail, so
+  /// we need to ensure that their processing isn't delayed until after the
+  /// transform or build has finished.
+  Stream<LogEntry> get onLog => _onLogPool.stream;
+  final _onLogPool = new StreamPool<LogEntry>.broadcast();
+
+  /// The current state of [this].
+  var _state = _TransformNodeState.PROCESSING;
+
+  /// Whether [this] has been marked as removed.
+  bool get _isRemoved => _onAssetController.isClosed;
+
+  /// Whether the most recent run of this transform has declared that it
+  /// consumes the primary input.
+  ///
+  /// Defaults to `false`. This is not meaningful unless [_state] is
+  /// [_TransformNodeState.APPLIED].
+  bool _consumePrimary = false;
+
+  TransformNode(this.phase, Transformer transformer, this.primary,
+      this._location)
+      : transformer = transformer,
+        _isLazy = transformer is LazyTransformer {
+    _primarySubscription = primary.onStateChange.listen((state) {
+      if (state.isRemoved) {
+        remove();
+      } else {
+        _dirty(primaryChanged: true);
+      }
+    });
+
+    _phaseSubscription = phase.previous.onAsset.listen((node) {
+      if (_missingInputs.contains(node.id)) _dirty(primaryChanged: false);
+    });
+
+    _process();
+  }
+
+  /// The [TransformInfo] describing this node.
+  ///
+  /// [TransformInfo] is the publicly-visible representation of a transform
+  /// node.
+  TransformInfo get info => new TransformInfo(transformer, primary.id);
+
+  /// Marks this transform as removed.
+  ///
+  /// This causes all of the transform's outputs to be marked as removed as
+  /// well. Normally this will be automatically done internally based on events
+  /// from the primary input, but it's possible for a transform to no longer be
+  /// valid even if its primary input still exists.
+  void remove() {
+    _onAssetController.close();
+    _onDoneController.close();
+    _primarySubscription.cancel();
+    _phaseSubscription.cancel();
+    _clearInputSubscriptions();
+    _clearOutputs();
+    if (_passThroughController != null) {
+      _passThroughController.setRemoved();
+      _passThroughController = null;
+    }
+  }
+
+  /// If [transformer] is lazy, ensures that its concrete outputs will be
+  /// generated.
+  void force() {
+    // TODO(nweiz): we might want to have a timeout after which, if the
+    // transform's outputs have gone unused, we switch it back to lazy mode.
+    if (!_isLazy) return;
+    _isLazy = false;
+    _dirty(primaryChanged: false);
+  }
+
+  /// Marks this transform as dirty.
+  ///
+  /// This causes all of the transform's outputs to be marked as dirty as well.
+  /// [primaryChanged] should be true if and only if [this] was set dirty
+  /// because [primary] changed.
+  void _dirty({bool primaryChanged: false}) {
+    if (!primaryChanged && _state.isNotPrimary) return;
+
+    if (_passThroughController != null) _passThroughController.setDirty();
+    for (var controller in _outputControllers.values) {
+      controller.setDirty();
+    }
+
+    if (_state.isDone) {
+      if (primaryChanged) {
+        _process();
+      } else {
+        _apply();
+      }
+    } else if (primaryChanged) {
+      _state = _TransformNodeState.NEEDS_IS_PRIMARY;
+    } else if (!_state.needsIsPrimary) {
+      _state = _TransformNodeState.NEEDS_APPLY;
+    }
+  }
+
+  /// Determines whether [primary] is primary for [transformer], and if so runs
+  /// [transformer.apply].
+  void _process() {
+    // Clear all the old input subscriptions. If an input is re-used, we'll
+    // re-subscribe.
+    _clearInputSubscriptions();
+    _state = _TransformNodeState.PROCESSING;
+    primary.whenAvailable((_) {
+      _state = _TransformNodeState.PROCESSING;
+      return transformer.isPrimary(primary.asset.id);
+    }).catchError((error, stackTrace) {
+      // If the transform became dirty while processing, ignore any errors from
+      // it.
+      if (_state.needsIsPrimary || _isRemoved) return false;
+
+      // Catch all transformer errors and pipe them to the results stream. This
+      // is so a broken transformer doesn't take down the whole graph.
+      phase.cascade.reportError(_wrapException(error, stackTrace));
+
+      return false;
+    }).then((isPrimary) {
+      if (_isRemoved) return;
+      if (_state.needsIsPrimary) {
+        _process();
+      } else if (isPrimary) {
+        _apply();
+      } else {
+        _clearOutputs();
+        _emitPassThrough();
+        _state = _TransformNodeState.NOT_PRIMARY;
+        _onDoneController.add(null);
+      }
+    });
+  }
+
+  /// Applies this transform.
+  void _apply() {
+    assert(!_onAssetController.isClosed);
+
+    // Clear input subscriptions here as well as in [_process] because [_apply]
+    // may be restarted independently if only a secondary input changes.
+    _clearInputSubscriptions();
+    _state = _TransformNodeState.PROCESSING;
+    primary.whenAvailable((_) {
+      if (_state.needsIsPrimary) return null;
+      _state = _TransformNodeState.PROCESSING;
+      // TODO(nweiz): If [transformer] is a [DeclaringTransformer] but not a
+      // [LazyTransformer], we can get some mileage out of doing a declarative
+      // first so we know how to hook up the assets.
+      if (_isLazy) return _declareLazy();
+      return _applyImmediate();
+    }).catchError((error, stackTrace) {
+      // If the transform became dirty while processing, ignore any errors from
+      // it.
+      if (!_state.isProcessing || _isRemoved) return false;
+
+      // Catch all transformer errors and pipe them to the results stream. This
+      // is so a broken transformer doesn't take down the whole graph.
+      phase.cascade.reportError(_wrapException(error, stackTrace));
+      return true;
+    }).then((hadError) {
+      if (_isRemoved) return;
+
+      if (_state.needsIsPrimary) {
+        _process();
+      } else if (_state.needsApply) {
+        _apply();
+      } else {
+        assert(_state.isProcessing);
+        if (hadError) {
+          _clearOutputs();
+          _dontEmitPassThrough();
+        }
+
+        _state = _TransformNodeState.APPLIED;
+        _onDoneController.add(null);
+      }
+    });
+  }
+
+  /// Gets the asset for an input [id].
+  ///
+  /// If an input with [id] cannot be found, throws an [AssetNotFoundException].
+  Future<Asset> getInput(AssetId id) {
+    return phase.previous.getOutput(id).then((node) {
+      // Throw if the input isn't found. This ensures the transformer's apply
+      // is exited. We'll then catch this and report it through the proper
+      // results stream.
+      if (node == null) {
+        _missingInputs.add(id);
+        throw new AssetNotFoundException(id);
+      }
+
+      _inputSubscriptions.putIfAbsent(node.id, () {
+        return node.onStateChange.listen((_) => _dirty(primaryChanged: false));
+      });
+
+      return node.asset;
+    });
+  }
+
+  /// Applies the transform so that it produces concrete (as opposed to lazy)
+  /// outputs.
+  ///
+  /// Returns whether or not the transformer logged an error.
+  Future<bool> _applyImmediate() {
+    var transformController = new TransformController(this);
+    _onLogPool.add(transformController.onLog);
+
+    return syncFuture(() {
+      return transformer.apply(transformController.transform);
+    }).then((_) {
+      if (!_state.isProcessing || _onAssetController.isClosed) return false;
+      if (transformController.loggedError) return true;
+
+      _consumePrimary = transformController.consumePrimary;
+
+      var newOutputs = transformController.outputs;
+      // Any ids that are for a different package are invalid.
+      var invalidIds = newOutputs
+          .map((asset) => asset.id)
+          .where((id) => id.package != phase.cascade.package)
+          .toSet();
+      for (var id in invalidIds) {
+        newOutputs.removeId(id);
+        // TODO(nweiz): report this as a warning rather than a failing error.
+        phase.cascade.reportError(new InvalidOutputException(info, id));
+      }
+
+      // Remove outputs that used to exist but don't anymore.
+      for (var id in _outputControllers.keys.toList()) {
+        if (newOutputs.containsId(id)) continue;
+        _outputControllers.remove(id).setRemoved();
+      }
+
+      // Emit or stop emitting the pass-through asset between removing and
+      // adding outputs to ensure there are no collisions.
+      if (!newOutputs.containsId(primary.id)) {
+        _emitPassThrough();
+      } else {
+        _dontEmitPassThrough();
+      }
+
+      // Store any new outputs or new contents for existing outputs.
+      for (var asset in newOutputs) {
+        var controller = _outputControllers[asset.id];
+        if (controller != null) {
+          controller.setAvailable(asset);
+        } else {
+          var controller = new AssetNodeController.available(asset, this);
+          _outputControllers[asset.id] = controller;
+          _onAssetController.add(controller.node);
+        }
+      }
+
+      return false;
+    });
+  }
+
+  /// Applies the transform in declarative mode so that it produces lazy
+  /// outputs.
+  ///
+  /// Returns whether or not the transformer logged an error.
+  Future<bool> _declareLazy() {
+    var transformController = new DeclaringTransformController(this);
+
+    return syncFuture(() {
+      return (transformer as LazyTransformer)
+          .declareOutputs(transformController.transform);
+    }).then((_) {
+      if (!_state.isProcessing || _onAssetController.isClosed) return false;
+      if (transformController.loggedError) return true;
+
+      _consumePrimary = transformController.consumePrimary;
+
+      var newIds = transformController.outputIds;
+      var invalidIds =
+          newIds.where((id) => id.package != phase.cascade.package).toSet();
+      for (var id in invalidIds) {
+        newIds.remove(id);
+        // TODO(nweiz): report this as a warning rather than a failing error.
+        phase.cascade.reportError(new InvalidOutputException(info, id));
+      }
+
+      // Remove outputs that used to exist but don't anymore.
+      for (var id in _outputControllers.keys.toList()) {
+        if (newIds.contains(id)) continue;
+        _outputControllers.remove(id).setRemoved();
+      }
+
+      // Emit or stop emitting the pass-through asset between removing and
+      // adding outputs to ensure there are no collisions.
+      if (!newIds.contains(primary.id)) {
+        _emitPassThrough();
+      } else {
+        _dontEmitPassThrough();
+      }
+
+      for (var id in newIds) {
+        var controller = _outputControllers[id];
+        if (controller != null) {
+          controller.setLazy(force);
+        } else {
+          var controller = new AssetNodeController.lazy(id, force, this);
+          _outputControllers[id] = controller;
+          _onAssetController.add(controller.node);
+        }
+      }
+
+      return false;
+    });
+  }
+
+  /// Cancels all subscriptions to secondary input nodes.
+  void _clearInputSubscriptions() {
+    _missingInputs.clear();
+    for (var subscription in _inputSubscriptions.values) {
+      subscription.cancel();
+    }
+    _inputSubscriptions.clear();
+  }
+
+  /// Removes all output assets.
+  void _clearOutputs() {
+    // Remove all the previously-emitted assets.
+    for (var controller in _outputControllers.values) {
+      controller.setRemoved();
+    }
+    _outputControllers.clear();
+  }
+
+  /// Emit the pass-through asset if it's not being emitted already.
+  void _emitPassThrough() {
+    assert(!_outputControllers.containsKey(primary.id));
+
+    if (_consumePrimary) return;
+    if (_passThroughController == null) {
+      _passThroughController = new AssetNodeController.from(primary);
+      _onAssetController.add(_passThroughController.node);
+    } else {
+      _passThroughController.setAvailable(primary.asset);
+    }
+  }
+
+  /// Stop emitting the pass-through asset if it's being emitted already.
+  void _dontEmitPassThrough() {
+    if (_passThroughController == null) return;
+    _passThroughController.setRemoved();
+    _passThroughController = null;
+  }
+
+  BarbackException _wrapException(error, StackTrace stackTrace) {
+    if (error is! AssetNotFoundException) {
+      return new TransformerException(info, error, stackTrace);
+    } else {
+      return new MissingInputException(info, error.id);
+    }
+  }
+
+  String toString() =>
+    "transform node in $_location for $transformer on $primary";
+}
+
+/// The enum of states that [TransformNode] can be in.
+class _TransformNodeState {
+  /// The transform node is running [Transformer.isPrimary] or
+  /// [Transformer.apply] and doesn't need to re-run them.
+  ///
+  /// If there are no external changes by the time the processing finishes, this
+  /// will transition to [APPLIED] or [NOT_PRIMARY] depending on the result of
+  /// [Transformer.isPrimary]. If the primary input changes, this will
+  /// transition to [NEEDS_IS_PRIMARY]. If a secondary input changes, this will
+  /// transition to [NEEDS_APPLY].
+  static final PROCESSING = const _TransformNodeState._("processing");
+
+  /// The transform is running [Transformer.isPrimary] or [Transformer.apply],
+  /// but since it started the primary input changed, so it will need to re-run
+  /// [Transformer.isPrimary].
+  ///
+  /// This will always transition to [Transformer.PROCESSING].
+  static final NEEDS_IS_PRIMARY =
+    const _TransformNodeState._("needs isPrimary");
+
+  /// The transform is running [Transformer.apply], but since it started a
+  /// secondary input changed, so it will need to re-run [Transformer.apply].
+  ///
+  /// If there are no external changes by the time [Transformer.apply] finishes,
+  /// this will transition to [PROCESSING]. If the primary input changes, this
+  /// will transition to [NEEDS_IS_PRIMARY].
+  static final NEEDS_APPLY = const _TransformNodeState._("needs apply");
+
+  /// The transform has finished running [Transformer.apply], whether or not it
+  /// emitted an error.
+  ///
+  /// If the primary input or a secondary input changes, this will transition to
+  /// [PROCESSING].
+  static final APPLIED = const _TransformNodeState._("applied");
+
+  /// The transform has finished running [Transformer.isPrimary], which returned
+  /// `false`.
+  ///
+  /// If the primary input changes, this will transition to [PROCESSING].
+  static final NOT_PRIMARY = const _TransformNodeState._("not primary");
+
+  /// Whether [this] is [PROCESSING].
+  bool get isProcessing => this == _TransformNodeState.PROCESSING;
+
+  /// Whether [this] is [NEEDS_IS_PRIMARY].
+  bool get needsIsPrimary => this == _TransformNodeState.NEEDS_IS_PRIMARY;
+
+  /// Whether [this] is [NEEDS_APPLY].
+  bool get needsApply => this == _TransformNodeState.NEEDS_APPLY;
+
+  /// Whether [this] is [APPLIED].
+  bool get isApplied => this == _TransformNodeState.APPLIED;
+
+  /// Whether [this] is [NOT_PRIMARY].
+  bool get isNotPrimary => this == _TransformNodeState.NOT_PRIMARY;
+
+  /// Whether the transform has finished running [Transformer.isPrimary] and
+  /// [Transformer.apply].
+  ///
+  /// Specifically, whether [this] is [APPLIED] or [NOT_PRIMARY].
+  bool get isDone => isApplied || isNotPrimary;
+
+  final String name;
+
+  const _TransformNodeState._(this.name);
+
+  String toString() => name;
+}