Add StackTrace.fromString constructor.

Remove _RemoteStackTrace from dart:isolate and use the new version instead.

R=sgjesse@google.com

Review URL: https://codereview.chromium.org//1088433004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@45088 260f80e4-7a28-3924-810f-c04153c831b5

sdk/lib/core/stacktrace.dart

@@ -14,6 +14,22 @@ part of dart.core;
  * them programmatically.
  */
 abstract class StackTrace {
+  StackTrace();  // In case existing classes extend StackTrace.
+
+  /**
+   * Create a `StackTrace` object from [stackTraceString].
+   *
+   * The created stack trace will have a `toString` method returning
+   * `stackTraceString`.
+   *
+   * The `stackTraceString` can be a string returned by some other
+   * stack trace, or it can be any string at all.
+   * If the string doesn't look like a stack trace, code that interprets
+   * stack traces is likely to fail, so fake stack traces should be used
+   * with care.
+   */
+  factory StackTrace.fromString(String stackTraceString) = _StringStackTrace;
+
   /**
    * Returns a [String] representation of the stack trace.
    *
@@ -25,3 +41,8 @@ abstract class StackTrace {
   String toString();
 }
 
+class _StringStackTrace implements StackTrace {
+  final String _stackTrace;
+  _StringStackTrace(this._stackTrace);
+  String toString() => _stackTrace;
+}

sdk/lib/isolate/isolate.dart

@@ -372,6 +372,7 @@ class Isolate {
    * created by calling `toString` on the error.
    * The second element is a `String` representation of an accompanying
    * stack trace, or `null` if no stack trace was provided.
+   * To convert this back to a [StackTrace] object, use [StackTrace.fromString].
    *
    * Listening using the same port more than once does nothing. It will only
    * get each error once.
@@ -607,12 +608,6 @@ class RemoteError implements Error {
   final StackTrace stackTrace;
   RemoteError(String description, String stackDescription)
       : _description = description,
-        stackTrace = new _RemoteStackTrace(stackDescription);
+        stackTrace = new StackTrace.fromString(stackDescription);
   String toString() => _description;
 }
-
-class _RemoteStackTrace implements StackTrace {
-  String _trace;
-  _RemoteStackTrace(this._trace);
-  String toString() => _trace;
-}

tests/corelib/stacktrace_fromstring_test.dart

@@ -0,0 +1,41 @@
+// Copyright (c) 2015, 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 "package:expect/expect.dart";
+import "package:async_helper/async_helper.dart";
+import "dart:async";
+
+void main() {
+  StackTrace stack;
+  try { throw 0; } catch (e, s) { stack = s; }
+  var string = "$stack";
+  StackTrace stringTrace = new StackTrace.fromString(string);
+  Expect.isTrue(stringTrace is StackTrace);
+  Expect.equals(stack.toString(), stringTrace.toString());
+
+  string = "some random string, nothing like a StackTrace";
+  stringTrace = new StackTrace.fromString(string);
+  Expect.isTrue(stringTrace is StackTrace);
+  Expect.equals(string, stringTrace.toString());
+
+  // Use stacktrace asynchronously.
+  asyncStart();
+  var c = new Completer();
+  c.completeError(0, stringTrace);
+  c.future.then((v) {
+    throw "Unexpected value: $v";
+  }, onError: (e, s) {
+    Expect.equals(string, s.toString());
+  }).then((_) {
+    var c = new StreamController();
+    c.stream.listen((v) {
+      throw "Unexpected value: $v";
+    }, onError: (e, s) {
+      Expect.equals(string, s.toString());
+      asyncEnd();
+    });
+    c.addError(0, stringTrace);
+    c.close();
+  });
+}

tests/language/custom_await_stack_trace_test.dart

@@ -1,13 +1,13 @@
 import "dart:async";
 import "package:expect/expect.dart";
 
-class Blah extends StackTrace {
+class Blah implements StackTrace {
   Blah(this._trace);
-  
+
   toString() {
     return "Blah " + _trace.toString();
   }
-  
+
   var _trace;
 }