| // 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. |
| |
| import 'dart:async'; |
| import 'dart:collection'; |
| import 'dart:math' as math; |
| |
| import 'frame.dart'; |
| import 'stack_zone_specification.dart'; |
| import 'trace.dart'; |
| import 'utils.dart'; |
| |
| /// A function that handles errors in the zone wrapped by [Chain.capture]. |
| @Deprecated("Will be removed in stack_trace 2.0.0.") |
| typedef void ChainHandler(error, Chain chain); |
| |
| /// A chain of stack traces. |
| /// |
| /// A stack chain is a collection of one or more stack traces that collectively |
| /// represent the path from [main] through nested function calls to a particular |
| /// code location, usually where an error was thrown. Multiple stack traces are |
| /// necessary when using asynchronous functions, since the program's stack is |
| /// reset before each asynchronous callback is run. |
| /// |
| /// Stack chains can be automatically tracked using [Chain.capture]. This sets |
| /// up a new [Zone] in which the current stack chain is tracked and can be |
| /// accessed using [new Chain.current]. Any errors that would be top-leveled in |
| /// the zone can be handled, along with their associated chains, with the |
| /// `onError` callback. For example: |
| /// |
| /// Chain.capture(() { |
| /// // ... |
| /// }, onError: (error, stackChain) { |
| /// print("Caught error $error\n" |
| /// "$stackChain"); |
| /// }); |
| class Chain implements StackTrace { |
| /// The stack traces that make up this chain. |
| /// |
| /// Like the frames in a stack trace, the traces are ordered from most local |
| /// to least local. The first one is the trace where the actual exception was |
| /// raised, the second one is where that callback was scheduled, and so on. |
| final List<Trace> traces; |
| |
| /// The [StackZoneSpecification] for the current zone. |
| static StackZoneSpecification get _currentSpec => |
| Zone.current[#stack_trace.stack_zone.spec]; |
| |
| /// If [when] is `true`, runs [callback] in a [Zone] in which the current |
| /// stack chain is tracked and automatically associated with (most) errors. |
| /// |
| /// If [when] is `false`, this does not track stack chains. Instead, it's |
| /// identical to [runZoned], except that it wraps any errors in [new |
| /// Chain.forTrace]—which will only wrap the trace unless there's a different |
| /// [Chain.capture] active. This makes it easy for the caller to only capture |
| /// stack chains in debug mode or during development. |
| /// |
| /// If [onError] is passed, any error in the zone that would otherwise go |
| /// unhandled is passed to it, along with the [Chain] associated with that |
| /// error. Note that if [callback] produces multiple unhandled errors, |
| /// [onError] may be called more than once. If [onError] isn't passed, the |
| /// parent Zone's `unhandledErrorHandler` will be called with the error and |
| /// its chain. |
| /// |
| /// Note that even if [onError] isn't passed, this zone will still be an error |
| /// zone. This means that any errors that would cross the zone boundary are |
| /// considered unhandled. |
| /// |
| /// If [callback] returns a value, it will be returned by [capture] as well. |
| static /*=T*/ capture/*<T>*/(/*=T*/ callback(), |
| {void onError(error, Chain chain), bool when: true}) { |
| if (!when) { |
| var newOnError; |
| if (onError != null) { |
| newOnError = (error, stackTrace) { |
| onError(error, new Chain.forTrace(stackTrace)); |
| }; |
| } |
| |
| // TODO(rnystrom): Remove this cast if runZoned() gets a generic type. |
| return runZoned(callback, onError: newOnError) as dynamic/*=T*/; |
| } |
| |
| var spec = new StackZoneSpecification(onError); |
| return runZoned(() { |
| try { |
| return callback(); |
| } catch (error, stackTrace) { |
| // TODO(nweiz): Don't special-case this when issue 19566 is fixed. |
| return Zone.current.handleUncaughtError(error, stackTrace); |
| } |
| }, zoneSpecification: spec.toSpec(), zoneValues: { |
| #stack_trace.stack_zone.spec: spec |
| }) as dynamic/*=T*/; |
| // TODO(rnystrom): Remove this cast if runZoned() gets a generic type. |
| } |
| |
| /// Returns [futureOrStream] unmodified. |
| /// |
| /// Prior to Dart 1.7, this was necessary to ensure that stack traces for |
| /// exceptions reported with [Completer.completeError] and |
| /// [StreamController.addError] were tracked correctly. |
| @Deprecated("Chain.track is not necessary in Dart 1.7+.") |
| static track(futureOrStream) => futureOrStream; |
| |
| /// Returns the current stack chain. |
| /// |
| /// By default, the first frame of the first trace will be the line where |
| /// [Chain.current] is called. If [level] is passed, the first trace will |
| /// start that many frames up instead. |
| /// |
| /// If this is called outside of a [capture] zone, it just returns a |
| /// single-trace chain. |
| factory Chain.current([int level=0]) { |
| if (_currentSpec != null) return _currentSpec.currentChain(level + 1); |
| return new Chain([new Trace.current(level + 1)]); |
| } |
| |
| /// Returns the stack chain associated with [trace]. |
| /// |
| /// The first stack trace in the returned chain will always be [trace] |
| /// (converted to a [Trace] if necessary). If there is no chain associated |
| /// with [trace] or if this is called outside of a [capture] zone, this just |
| /// returns a single-trace chain containing [trace]. |
| /// |
| /// If [trace] is already a [Chain], it will be returned as-is. |
| factory Chain.forTrace(StackTrace trace) { |
| if (trace is Chain) return trace; |
| if (_currentSpec == null) return new Chain([new Trace.from(trace)]); |
| return _currentSpec.chainFor(trace); |
| } |
| |
| /// Parses a string representation of a stack chain. |
| /// |
| /// If [chain] is the output of a call to [Chain.toString], it will be parsed |
| /// as a full stack chain. Otherwise, it will be parsed as in [Trace.parse] |
| /// and returned as a single-trace chain. |
| factory Chain.parse(String chain) { |
| if (chain.isEmpty) return new Chain([]); |
| if (!chain.contains(chainGap)) return new Chain([new Trace.parse(chain)]); |
| |
| return new Chain( |
| chain.split(chainGap).map((trace) => new Trace.parseFriendly(trace))); |
| } |
| |
| /// Returns a new [Chain] comprised of [traces]. |
| Chain(Iterable<Trace> traces) |
| : traces = new UnmodifiableListView<Trace>(traces.toList()); |
| |
| /// Returns a terser version of [this]. |
| /// |
| /// This calls [Trace.terse] on every trace in [traces], and discards any |
| /// trace that contain only internal frames. |
| Chain get terse => foldFrames((_) => false, terse: true); |
| |
| /// Returns a new [Chain] based on [this] where multiple stack frames matching |
| /// [predicate] are folded together. |
| /// |
| /// This means that whenever there are multiple frames in a row that match |
| /// [predicate], only the last one is kept. In addition, traces that are |
| /// composed entirely of frames matching [predicate] are omitted. |
| /// |
| /// This is useful for limiting the amount of library code that appears in a |
| /// stack trace by only showing user code and code that's called by user code. |
| /// |
| /// If [terse] is true, this will also fold together frames from the core |
| /// library or from this package, and simplify core library frames as in |
| /// [Trace.terse]. |
| Chain foldFrames(bool predicate(Frame frame), {bool terse: false}) { |
| var foldedTraces = traces.map( |
| (trace) => trace.foldFrames(predicate, terse: terse)); |
| var nonEmptyTraces = foldedTraces.where((trace) { |
| // Ignore traces that contain only folded frames. |
| if (trace.frames.length > 1) return true; |
| if (trace.frames.isEmpty) return false; |
| |
| // In terse mode, the trace may have removed an outer folded frame, |
| // leaving a single non-folded frame. We can detect a folded frame because |
| // it has no line information. |
| if (!terse) return false; |
| return trace.frames.single.line != null; |
| }); |
| |
| // If all the traces contain only internal processing, preserve the last |
| // (top-most) one so that the chain isn't empty. |
| if (nonEmptyTraces.isEmpty && foldedTraces.isNotEmpty) { |
| return new Chain([foldedTraces.last]); |
| } |
| |
| return new Chain(nonEmptyTraces); |
| } |
| |
| /// Converts [this] to a [Trace]. |
| /// |
| /// The trace version of a chain is just the concatenation of all the traces |
| /// in the chain. |
| Trace toTrace() => new Trace(traces.expand((trace) => trace.frames)); |
| |
| String toString() { |
| // Figure out the longest path so we know how much to pad. |
| var longest = traces.map((trace) { |
| return trace.frames.map((frame) => frame.location.length) |
| .fold(0, math.max); |
| }).fold(0, math.max); |
| |
| // Don't call out to [Trace.toString] here because that doesn't ensure that |
| // padding is consistent across all traces. |
| return traces.map((trace) { |
| return trace.frames.map((frame) { |
| return '${padRight(frame.location, longest)} ${frame.member}\n'; |
| }).join(); |
| }).join(chainGap); |
| } |
| } |