Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/stack_trace/src/trace.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 trace;
+
+import 'dart:collection';
+import 'dart:math' as math;
+
+import 'chain.dart';
+import 'frame.dart';
+import 'lazy_trace.dart';
+import 'utils.dart';
+import 'vm_trace.dart';
+
+final _terseRegExp = new RegExp(r"(-patch)?(/.*)?$");
+
+/// A RegExp to match V8's stack traces.
+///
+/// V8's traces start with a line that's either just "Error" or else is a
+/// description of the exception that occurred. That description can be multiple
+/// lines, so we just look for any line other than the first that begins with
+/// three or four spaces and "at".
+final _v8Trace = new RegExp(r"\n    ?at ");
+
+/// A RegExp to match indidual lines of V8's stack traces.
+///
+/// This is intended to filter out the leading exception details of the trace
+/// though it is possible for the message to match this as well.
+final _v8TraceLine = new RegExp(r"    ?at ");
+
+/// A RegExp to match Firefox and Safari's stack traces.
+///
+/// Firefox and Safari have very similar stack trace formats, so we use the same
+/// logic for parsing them.
+///
+/// Firefox's trace frames start with the name of the function in which the
+/// error occurred, possibly including its parameters inside `()`. For example,
+/// `.VW.call$0("arg")@http://pub.dartlang.org/stuff.dart.js:560`.
+///
+/// Safari traces occasionally don't include the initial method name followed by
+/// "@", and they always have both the line and column number (or just a
+/// trailing colon if no column number is available). They can also contain
+/// empty lines or lines consisting only of `[native code]`.
+final _firefoxSafariTrace = new RegExp(
+    r"^"
+    r"(" // Member description. Not present in some Safari frames.
+      r"([.0-9A-Za-z_$/<]|\(.*\))*" // Member name and arguments.
+      r"@"
+    r")?"
+    r"[^\s]*" // Frame URL.
+    r":\d*" // Line or column number. Some older frames only have a line number.
+    r"$", multiLine: true);
+
+/// A RegExp to match this package's stack traces.
+final _friendlyTrace = new RegExp(r"^[^\s]+( \d+(:\d+)?)?[ \t]+[^\s]+$",
+    multiLine: true);
+
+/// A stack trace, comprised of a list of stack frames.
+class Trace implements StackTrace {
+  /// The stack frames that comprise this stack trace.
+  final List<Frame> frames;
+
+  /// Returns a human-readable representation of [stackTrace]. If [terse] is
+  /// set, this folds together multiple stack frames from the Dart core
+  /// libraries, so that only the core library method directly called from user
+  /// code is visible (see [Trace.terse]).
+  static String format(StackTrace stackTrace, {bool terse: true}) {
+    var trace = new Trace.from(stackTrace);
+    if (terse) trace = trace.terse;
+    return trace.toString();
+  }
+
+  /// Returns the current stack trace.
+  ///
+  /// By default, the first frame of this trace will be the line where
+  /// [Trace.current] is called. If [level] is passed, the trace will start that
+  /// many frames up instead.
+  factory Trace.current([int level=0]) {
+    if (level < 0) {
+      throw new ArgumentError("Argument [level] must be greater than or equal "
+          "to 0.");
+    }
+
+    try {
+      throw '';
+    } catch (_, nativeTrace) {
+      var trace = new Trace.from(nativeTrace);
+      return new LazyTrace(() => new Trace(trace.frames.skip(level + 1)));
+    }
+  }
+
+  /// Returns a new stack trace containing the same data as [trace].
+  ///
+  /// If [trace] is a native [StackTrace], its data will be parsed out; if it's
+  /// a [Trace], it will be returned as-is.
+  factory Trace.from(StackTrace trace) {
+    // Normally explicitly validating null arguments is bad Dart style, but here
+    // the natural failure will only occur when the LazyTrace is materialized,
+    // and we want to provide an error that's more local to the actual problem.
+    if (trace == null) {
+      throw new ArgumentError("Cannot create a Trace from null.");
+    }
+
+    if (trace is Trace) return trace;
+    if (trace is Chain) return trace.toTrace();
+    return new LazyTrace(() => new Trace.parse(trace.toString()));
+  }
+
+  /// Parses a string representation of a stack trace.
+  ///
+  /// [trace] should be formatted in the same way as a Dart VM or browser stack
+  /// trace.
+  factory Trace.parse(String trace) {
+    try {
+      if (trace.isEmpty) return new Trace(<Frame>[]);
+      if (trace.contains(_v8Trace)) return new Trace.parseV8(trace);
+      if (trace.contains(_firefoxSafariTrace)) {
+        return new Trace.parseFirefox(trace);
+      }
+      if (trace.contains(_friendlyTrace)) {
+        return new Trace.parseFriendly(trace);
+      }
+
+      // Default to parsing the stack trace as a VM trace. This is also hit on
+      // IE and Safari, where the stack trace is just an empty string (issue
+      // 11257).
+      return new Trace.parseVM(trace);
+    } on FormatException catch (error) {
+      throw new FormatException('${error.message}\nStack trace:\n$trace');
+    }
+  }
+
+  /// Parses a string representation of a Dart VM stack trace.
+  Trace.parseVM(String trace)
+      : this(trace.trim().split("\n").
+            // TODO(nweiz): remove this when issue 15920 is fixed.
+            where((line) => line.isNotEmpty).
+            map((line) => new Frame.parseVM(line)));
+
+  /// Parses a string representation of a Chrome/V8 stack trace.
+  Trace.parseV8(String trace)
+      : this(trace.split("\n").skip(1)
+          // It's possible that an Exception's description contains a line that
+          // looks like a V8 trace line, which will screw this up.
+          // Unfortunately, that's impossible to detect.
+          .skipWhile((line) => !line.startsWith(_v8TraceLine))
+          .map((line) => new Frame.parseV8(line)));
+
+  /// Parses a string representation of an Internet Explorer stack trace.
+  ///
+  /// IE10+ traces look just like V8 traces. Prior to IE10, stack traces can't
+  /// be retrieved.
+  Trace.parseIE(String trace)
+      : this.parseV8(trace);
+
+  /// Parses a string representation of a Firefox stack trace.
+  Trace.parseFirefox(String trace)
+      : this(trace.trim().split("\n")
+          .where((line) => line.isNotEmpty && line != '[native code]')
+          .map((line) => new Frame.parseFirefox(line)));
+
+  /// Parses a string representation of a Safari stack trace.
+  Trace.parseSafari(String trace)
+      : this.parseFirefox(trace);
+
+  /// Parses a string representation of a Safari 6.1+ stack trace.
+  @Deprecated("Use Trace.parseSafari instead.")
+  Trace.parseSafari6_1(String trace)
+      : this.parseSafari(trace);
+
+  /// Parses a string representation of a Safari 6.0 stack trace.
+  @Deprecated("Use Trace.parseSafari instead.")
+  Trace.parseSafari6_0(String trace)
+      : this(trace.trim().split("\n")
+          .where((line) => line != '[native code]')
+          .map((line) => new Frame.parseFirefox(line)));
+
+  /// Parses this package's string representation of a stack trace.
+  ///
+  /// This also parses string representations of [Chain]s. They parse to the
+  /// same trace that [Chain.toTrace] would return.
+  Trace.parseFriendly(String trace)
+      : this(trace.trim().split("\n")
+          // Filter out asynchronous gaps from [Chain]s.
+          .where((line) => !line.startsWith('====='))
+          .map((line) => new Frame.parseFriendly(line)));
+
+  /// Returns a new [Trace] comprised of [frames].
+  Trace(Iterable<Frame> frames)
+      : frames = new UnmodifiableListView<Frame>(frames.toList());
+
+  /// Returns a VM-style [StackTrace] object.
+  ///
+  /// The return value's [toString] method will always return a string
+  /// representation in the Dart VM's stack trace format, regardless of what
+  /// platform is being used.
+  StackTrace get vmTrace => new VMTrace(frames);
+
+  /// Returns a terser version of [this].
+  ///
+  /// This is accomplished by folding together multiple stack frames from the
+  /// core library or from this package, as in [foldFrames]. Remaining core
+  /// library frames have their libraries, "-patch" suffixes, and line numbers
+  /// removed.
+  Trace get terse {
+    return new Trace(foldFrames((frame) {
+      return frame.isCore || frame.package == 'stack_trace';
+    }).frames.map((frame) {
+      if (!frame.isCore) return frame;
+      var library = frame.library.replaceAll(_terseRegExp, '');
+      return new Frame(Uri.parse(library), null, null, frame.member);
+    }));
+  }
+
+  /// Returns a new [Trace] 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.
+  ///
+  /// 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.
+  Trace foldFrames(bool predicate(Frame frame)) {
+    var newFrames = <Frame>[];
+    for (var frame in frames.reversed) {
+      if (!predicate(frame)) {
+        newFrames.add(frame);
+      } else if (newFrames.isEmpty || !predicate(newFrames.last)) {
+        newFrames.add(new Frame(
+            frame.uri, frame.line, frame.column, frame.member));
+      }
+    }
+
+    return new Trace(newFrames.reversed);
+  }
+
+  /// Returns a human-readable string representation of [this].
+  String toString() {
+    // Figure out the longest path so we know how much to pad.
+    var longest = frames.map((frame) => frame.location.length)
+        .fold(0, math.max);
+
+    // Print out the stack trace nicely formatted.
+    return frames.map((frame) {
+      return '${padRight(frame.location, longest)}  ${frame.member}\n';
+    }).join();
+  }
+}