Introduce StackTraceOnThrowMixin.

sdk/lib/core/errors.dart

 // Copyright (c) 2012, 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.
 
 part of dart.core;
 
 class Error {
+  const Error();
+
   /**
    * Safely convert a value to a [String] description.
    *
    * The conversion is guaranteed to not throw, so it won't use the object's
    * toString method.
    */
   static String safeToString(Object object) {
     if (object is int || object is double || object is bool || null == object) {
       return object.toString();
     }
     if (object is String) {
       // TODO(ahe): Remove backslash when http://dartbug.com/4995 is fixed.
       String string = object;
       const backslash = '\\';
       String escaped = string
         .replaceAll('$backslash', '$backslash$backslash')
         .replaceAll('\n', '${backslash}n')
         .replaceAll('\r', '${backslash}r')
         .replaceAll('"',  '$backslash"');
       return '"$escaped"';
     }
     return _objectToString(object);
   }
 
   external static String _objectToString(Object object);
 
+  /**
+   * The stack trace of `this` error. May be null.
+   */
+  StackTrace get stackTrace => null;
+}
+
+/**
+ * Captures the stack trace when thrown.
+ */
+class StackTraceOnThrow {
+  /**
+   * Captures the current stack-trace when thrown.
+   *
+   * Classes extending or mixing-in this class will automatically have a stack
+   * trace captured the first time they are thrown. This stack trace is returned
+   * by the [stackTrace] getter.
+   *
+   * Throwing the object again will not cause overwrite the first stack trace,
+   * so bjects that are `StackTraceOnThrow` instances should not be reused.
+   */
   external StackTrace get stackTrace;
 }
 
 /**
  * Error thrown by the runtime system when an assert statement fails.
  */
-class AssertionError extends Error {
+class AssertionError extends Error with StackTraceOnThrow {
 }
 
 /**
  * Error thrown by the runtime system when a type assertion fails.
  */
 class TypeError extends AssertionError {
 }
 
 /**
  * Error thrown by the runtime system when a cast operation fails.
  */
-class CastError extends Error {
+class CastError extends Error with StackTraceOnThrow {
 }
 
 /**
  * Error thrown when attempting to throw [:null:].
  */
-class NullThrownError extends Error {
+class NullThrownError extends Error with StackTraceOnThrow {
   NullThrownError();
   String toString() => "Throw of null.";
 }
 
 /**
  * Error thrown when a function is passed an unacceptable argument.
  */
-class ArgumentError extends Error {
+class ArgumentError extends Error with StackTraceOnThrow {
   final message;
 
   /** The [message] describes the erroneous argument. */
   ArgumentError([this.message]);
 
   String toString() {
     if (message != null) {
       return "Illegal argument(s): $message";
     }
     return "Illegal argument(s)";
@@ skipping 26 matching lines @@
 
 
 /**
  * Error thrown when control reaches the end of a switch case.
  *
  * The Dart specification requires this error to be thrown when
  * control reaches the end of a switch case (except the last case
  * of a switch) without meeting a break or similar end of the control
  * flow.
  */
-class FallThroughError extends Error {
-  FallThroughError();
+class FallThroughError extends Error with StackTraceOnThrow {
 }
 
 
-class AbstractClassInstantiationError extends Error {
+class AbstractClassInstantiationError
+    extends Error with StackTraceOnThrow {
   final String _className;
   AbstractClassInstantiationError(String this._className);
   String toString() => "Cannot instantiate abstract class: '$_className'";
 }
 
 /**
  * Error thrown by the default implementation of [:noSuchMethod:] on [Object].
  */
-class NoSuchMethodError extends Error {
+class NoSuchMethodError extends Error with StackTraceOnThrow {
   final Object _receiver;
   final String _memberName;
   final List _arguments;
   final Map<String,dynamic> _namedArguments;
   final List _existingArgumentNames;
 
   /**
    * Create a [NoSuchMethodError] corresponding to a failed method call.
    *
    * The first parameter to this constructor is the receiver of the method call.
@@ skipping 17 matching lines @@
   external String toString();
 }
 
 
 /**
  * The operation was not allowed by the object.
  *
  * This [Error] is thrown when an instance cannot implement one of the methods
  * in its signature.
  */
-class UnsupportedError extends Error {
+class UnsupportedError extends Error with StackTraceOnThrow {
   final String message;
   UnsupportedError(this.message);
   String toString() => "Unsupported operation: $message";
 }
 
 
 /**
  * Thrown by operations that have not been implemented yet.
  *
  * This [Error] is thrown by unfinished code that hasn't yet implemented
  * all the features it needs.
  *
  * If a class is not intending to implement the feature, it should throw
  * an [UnsupportedError] instead. This error is only intended for
  * use during development.
  */
-class UnimplementedError extends Error implements UnsupportedError {
+class UnimplementedError
+    extends Error with StackTraceOnThrow implements UnsupportedError {
   final String message;
   UnimplementedError([String this.message]);
   String toString() => (this.message != null
                         ? "UnimplementedError: $message"
                         : "UnimplementedError");
 }
 
 
 /**
  * The operation was not allowed by the current state of the object.
  *
  * This is a generic error used for a variety of different erroneous
  * actions. The message should be descriptive.
  */
-class StateError extends Error {
+class StateError extends Error with StackTraceOnThrow {
   final String message;
   StateError(this.message);
   String toString() => "Bad state: $message";
 }
 
 
 /**
  * Error occurring when a collection is modified during iteration.
  *
  * Some modifications may be allowed for some collections, so each collection
  * ([Iterable] or similar collection of values) should declare which operations
  * are allowed during an iteration.
  */
-class ConcurrentModificationError extends Error {
+class ConcurrentModificationError extends Error with StackTraceOnThrow {
   /** The object that was modified in an incompatible way. */
   final Object modifiedObject;
 
   ConcurrentModificationError([this.modifiedObject]);
 
   String toString() {
     if (modifiedObject == null) {
       return "Concurrent modification during iteration.";
     }
     return "Concurrent modification during iteration: "
            "${Error.safeToString(modifiedObject)}.";
   }
 }
 
 
-class OutOfMemoryError implements Error {
+class OutOfMemoryError extends Error {
   const OutOfMemoryError();
   String toString() => "Out of Memory";
-
-  StackTrace get stackTrace => null;
 }
 
 
-class StackOverflowError implements Error {
+class StackOverflowError extends Error {
   const StackOverflowError();
   String toString() => "Stack Overflow";
-
-  StackTrace get stackTrace => null;
 }
 
 /**
  * Error thrown when a lazily initialized variable cannot be initialized.
  *
  * A static/library variable with an initializer expression is initialized
  * the first time it is read. If evaluating the initializer expression causes
  * another read of the variable, this error is thrown.
  */
-class CyclicInitializationError extends Error {
+class CyclicInitializationError extends Error with StackTraceOnThrow {
   final String variableName;
   CyclicInitializationError([this.variableName]);
   String toString() => variableName == null
       ? "Reading static variable during its initialization"
       : "Reading static variable '$variableName' during its initialization";
 }