Revert "Rewrite Futures."

sdk/lib/async/stream.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.
 
 part of dart.async;
 
 // -------------------------------------------------------------------
 // Core Stream types
 // -------------------------------------------------------------------
 
@@ skipping 254 matching lines @@
    * Returns the result of [:streamTransformer.bind:] itself.
    */
   Stream transform(StreamTransformer<T, dynamic> streamTransformer) {
     return streamTransformer.bind(this);
   }
 
   /**
    * Reduces a sequence of values by repeatedly applying [combine].
    */
   Future<T> reduce(T combine(T previous, T element)) {
-    _Future<T> result = new _Future<T>();
+    _FutureImpl<T> result = new _FutureImpl<T>();
     bool seenFirst = false;
     T value;
     StreamSubscription subscription;
     subscription = this.listen(
       (T element) {
         if (seenFirst) {
           _runUserCode(() => combine(value, element),
                        (T newValue) { value = newValue; },
                        _cancelAndError(subscription, result));
         } else {
           value = element;
           seenFirst = true;
         }
       },
-      onError: result._completeError,
+      onError: result._setError,
       onDone: () {
         if (!seenFirst) {
-          result._completeError(new StateError("No elements"));
+          result._setError(new StateError("No elements"));
         } else {
-          result._complete(value);
+          result._setValue(value);
         }
       },
       cancelOnError: true
     );
     return result;
   }
 
   /** Reduces a sequence of values by repeatedly applying [combine]. */
   Future fold(var initialValue, combine(var previous, T element)) {
-    _Future result = new _Future();
+    _FutureImpl result = new _FutureImpl();
     var value = initialValue;
     StreamSubscription subscription;
     subscription = this.listen(
       (T element) {
         _runUserCode(
           () => combine(value, element),
           (newValue) { value = newValue; },
           _cancelAndError(subscription, result)
         );
       },
       onError: (e) {
-        result._completeError(e);
+        result._setError(e);
       },
       onDone: () {
-        result._complete(value);
+        result._setValue(value);
       },
       cancelOnError: true);
     return result;
   }
 
   /**
    * Collects string of data events' string representations.
    *
    * If [separator] is provided, it is inserted between any two
    * elements.
    *
    * Any error in the stream causes the future to complete with that
    * error. Otherwise it completes with the collected string when
    * the "done" event arrives.
    */
   Future<String> join([String separator = ""]) {
-    _Future<String> result = new _Future<String>();
+    _FutureImpl<String> result = new _FutureImpl<String>();
     StringBuffer buffer = new StringBuffer();
     StreamSubscription subscription;
     bool first = true;
     subscription = this.listen(
       (T element) {
         if (!first) {
           buffer.write(separator);
         }
         first = false;
         try {
           buffer.write(element);
         } catch (e, s) {
           subscription.cancel();
-          result._completeError(_asyncError(e, s));
+          result._setError(_asyncError(e, s));
         }
       },
       onError: (e) {
-        result._completeError(e);
+        result._setError(e);
       },
       onDone: () {
-        result._complete(buffer.toString());
+        result._setValue(buffer.toString());
       },
       cancelOnError: true);
     return result;
   }
 
   /**
    * Checks whether [needle] occurs in the elements provided by this stream.
    *
    * Completes the [Future] when the answer is known.
    * If this stream reports an error, the [Future] will report that error.
    */
   Future<bool> contains(Object needle) {
-    _Future<bool> future = new _Future<bool>();
+    _FutureImpl<bool> future = new _FutureImpl<bool>();
     StreamSubscription subscription;
     subscription = this.listen(
         (T element) {
           _runUserCode(
             () => (element == needle),
             (bool isMatch) {
               if (isMatch) {
                 subscription.cancel();
-                future._complete(true);
+                future._setValue(true);
               }
             },
             _cancelAndError(subscription, future)
           );
         },
-        onError: future._completeError,
+        onError: future._setError,
         onDone: () {
-          future._complete(false);
+          future._setValue(false);
         },
         cancelOnError: true);
     return future;
   }
 
   /**
    * Executes [action] on each data event of the stream.
    *
    * Completes the returned [Future] when all events of the stream
    * have been processed. Completes the future with an error if the
    * stream has an error event, or if [action] throws.
    */
   Future forEach(void action(T element)) {
-    _Future future = new _Future();
+    _FutureImpl future = new _FutureImpl();
     StreamSubscription subscription;
     subscription = this.listen(
         (T element) {
           _runUserCode(
             () => action(element),
             (_) {},
             _cancelAndError(subscription, future)
           );
         },
-        onError: future._completeError,
+        onError: future._setError,
         onDone: () {
-          future._complete(null);
+          future._setValue(null);
         },
         cancelOnError: true);
     return future;
   }
 
   /**
    * Checks whether [test] accepts all elements provided by this stream.
    *
    * Completes the [Future] when the answer is known.
    * If this stream reports an error, the [Future] will report that error.
    */
   Future<bool> every(bool test(T element)) {
-    _Future<bool> future = new _Future<bool>();
+    _FutureImpl<bool> future = new _FutureImpl<bool>();
     StreamSubscription subscription;
     subscription = this.listen(
         (T element) {
           _runUserCode(
             () => test(element),
             (bool isMatch) {
               if (!isMatch) {
                 subscription.cancel();
-                future._complete(false);
+                future._setValue(false);
               }
             },
             _cancelAndError(subscription, future)
           );
         },
-        onError: future._completeError,
+        onError: future._setError,
         onDone: () {
-          future._complete(true);
+          future._setValue(true);
         },
         cancelOnError: true);
     return future;
   }
 
   /**
    * Checks whether [test] accepts any element provided by this stream.
    *
    * Completes the [Future] when the answer is known.
    * If this stream reports an error, the [Future] will report that error.
    */
   Future<bool> any(bool test(T element)) {
-    _Future<bool> future = new _Future<bool>();
+    _FutureImpl<bool> future = new _FutureImpl<bool>();
     StreamSubscription subscription;
     subscription = this.listen(
         (T element) {
           _runUserCode(
             () => test(element),
             (bool isMatch) {
               if (isMatch) {
                 subscription.cancel();
-                future._complete(true);
+                future._setValue(true);
               }
             },
             _cancelAndError(subscription, future)
           );
         },
-        onError: future._completeError,
+        onError: future._setError,
         onDone: () {
-          future._complete(false);
+          future._setValue(false);
         },
         cancelOnError: true);
     return future;
   }
 
 
   /** Counts the elements in the stream. */
   Future<int> get length {
-    _Future<int> future = new _Future<int>();
+    _FutureImpl<int> future = new _FutureImpl<int>();
     int count = 0;
     this.listen(
       (_) { count++; },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._complete(count);
+        future._setValue(count);
       },
       cancelOnError: true);
     return future;
   }
 
   /** Reports whether this stream contains any elements. */
   Future<bool> get isEmpty {
-    _Future<bool> future = new _Future<bool>();
+    _FutureImpl<bool> future = new _FutureImpl<bool>();
     StreamSubscription subscription;
     subscription = this.listen(
       (_) {
         subscription.cancel();
-        future._complete(false);
+        future._setValue(false);
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._complete(true);
+        future._setValue(true);
       },
       cancelOnError: true);
     return future;
   }
 
   /** Collects the data of this stream in a [List]. */
   Future<List<T>> toList() {
     List<T> result = <T>[];
-    _Future<List<T>> future = new _Future<List<T>>();
+    _FutureImpl<List<T>> future = new _FutureImpl<List<T>>();
     this.listen(
       (T data) {
         result.add(data);
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._complete(result);
+        future._setValue(result);
       },
       cancelOnError: true);
     return future;
   }
 
   /** Collects the data of this stream in a [Set]. */
   Future<Set<T>> toSet() {
     Set<T> result = new Set<T>();
-    _Future<Set<T>> future = new _Future<Set<T>>();
+    _FutureImpl<Set<T>> future = new _FutureImpl<Set<T>>();
     this.listen(
       (T data) {
         result.add(data);
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._complete(result);
+        future._setValue(result);
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Discards all data on the stream, but signals when it's done or an error
    * occured.
    *
    * When subscribing using [drain], cancelOnError will be true. This means
@@ skipping 71 matching lines @@
    * If an error event occurs before the first data event, the resulting future
    * is completed with that error.
    *
    * If this stream is empty (a done event occurs before the first data event),
    * the resulting future completes with a [StateError].
    *
    * Except for the type of the error, this method is equivalent to
    * [:this.elementAt(0):].
    */
   Future<T> get first {
-    _Future<T> future = new _Future<T>();
+    _FutureImpl<T> future = new _FutureImpl<T>();
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         subscription.cancel();
-        future._complete(value);
+        future._setValue(value);
         return;
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._completeError(new StateError("No elements"));
+        future._setError(new StateError("No elements"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Returns the last element of the stream.
    *
    * If an error event occurs before the first data event, the resulting future
    * is completed with that error.
    *
    * If this stream is empty (a done event occurs before the first data event),
    * the resulting future completes with a [StateError].
    */
   Future<T> get last {
-    _Future<T> future = new _Future<T>();
+    _FutureImpl<T> future = new _FutureImpl<T>();
     T result = null;
     bool foundResult = false;
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         foundResult = true;
         result = value;
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
         if (foundResult) {
-          future._complete(result);
+          future._setValue(result);
           return;
         }
-        future._completeError(new StateError("No elements"));
+        future._setError(new StateError("No elements"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Returns the single element.
    *
    * If [this] is empty or has more than one element throws a [StateError].
    */
   Future<T> get single {
-    _Future<T> future = new _Future<T>();
+    _FutureImpl<T> future = new _FutureImpl<T>();
     T result = null;
     bool foundResult = false;
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         if (foundResult) {
           subscription.cancel();
           // This is the second element we get.
           Error error = new StateError("More than one element");
-          future._completeError(error);
+          future._setError(error);
           return;
         }
         foundResult = true;
         result = value;
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
         if (foundResult) {
-          future._complete(result);
+          future._setValue(result);
           return;
         }
-        future._completeError(new StateError("No elements"));
+        future._setError(new StateError("No elements"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Finds the first element of this stream matching [test].
    *
    * Returns a future that is filled with the first element of this stream
    * that [test] returns true for.
    *
    * If no such element is found before this stream is done, and a
    * [defaultValue] function is provided, the result of calling [defaultValue]
    * becomes the value of the future.
    *
    * If an error occurs, or if this stream ends without finding a match and
    * with no [defaultValue] function provided, the future will receive an
    * error.
    */
   Future<dynamic> firstWhere(bool test(T element), {Object defaultValue()}) {
-    _Future<dynamic> future = new _Future();
+    _FutureImpl<dynamic> future = new _FutureImpl();
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         _runUserCode(
           () => test(value),
           (bool isMatch) {
             if (isMatch) {
               subscription.cancel();
-              future._complete(value);
+              future._setValue(value);
             }
           },
           _cancelAndError(subscription, future)
         );
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
         if (defaultValue != null) {
-          _runUserCode(defaultValue, future._complete, future._completeError);
+          _runUserCode(defaultValue, future._setValue, future._setError);
           return;
         }
-        future._completeError(new StateError("firstMatch ended without match"));
+        future._setError(new StateError("firstMatch ended without match"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Finds the last element in this stream matching [test].
    *
    * As [firstWhere], except that the last matching element is found.
    * That means that the result cannot be provided before this stream
    * is done.
    */
   Future<dynamic> lastWhere(bool test(T element), {Object defaultValue()}) {
-    _Future<dynamic> future = new _Future();
+    _FutureImpl<dynamic> future = new _FutureImpl();
     T result = null;
     bool foundResult = false;
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         _runUserCode(
           () => true == test(value),
           (bool isMatch) {
             if (isMatch) {
               foundResult = true;
               result = value;
             }
           },
           _cancelAndError(subscription, future)
         );
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
         if (foundResult) {
-          future._complete(result);
+          future._setValue(result);
           return;
         }
         if (defaultValue != null) {
-          _runUserCode(defaultValue, future._complete, future._completeError);
+          _runUserCode(defaultValue, future._setValue, future._setError);
           return;
         }
-        future._completeError(new StateError("lastMatch ended without match"));
+        future._setError(new StateError("lastMatch ended without match"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Finds the single element in this stream matching [test].
    *
    * Like [lastMatch], except that it is an error if more than one
    * matching element occurs in the stream.
    */
   Future<T> singleWhere(bool test(T element)) {
-    _Future<T> future = new _Future<T>();
+    _FutureImpl<T> future = new _FutureImpl<T>();
     T result = null;
     bool foundResult = false;
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         _runUserCode(
           () => true == test(value),
           (bool isMatch) {
             if (isMatch) {
               if (foundResult) {
                 subscription.cancel();
-                future._completeError(
+                future._setError(
                     new StateError('Multiple matches for "single"'));
                 return;
               }
               foundResult = true;
               result = value;
             }
           },
           _cancelAndError(subscription, future)
         );
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
         if (foundResult) {
-          future._complete(result);
+          future._setValue(result);
           return;
         }
-        future._completeError(new StateError("single ended without match"));
+        future._setError(new StateError("single ended without match"));
       },
       cancelOnError: true);
     return future;
   }
 
   /**
    * Returns the value of the [index]th data event of this stream.
    *
    * Stops listening to the stream after a value has been found.
    *
    * If an error event occurs before the value is found, the future completes
    * with this error.
    *
    * If a done event occurs before the value is found, the future completes
    * with a [RangeError].
    */
   Future<T> elementAt(int index) {
     if (index is! int || index < 0) throw new ArgumentError(index);
-    _Future<T> future = new _Future<T>();
+    _FutureImpl<T> future = new _FutureImpl<T>();
     StreamSubscription subscription;
     subscription = this.listen(
       (T value) {
         if (index == 0) {
           subscription.cancel();
-          future._complete(value);
+          future._setValue(value);
           return;
         }
         index -= 1;
       },
-      onError: future._completeError,
+      onError: future._setError,
       onDone: () {
-        future._completeError(new RangeError.value(index));
+        future._setError(new RangeError.value(index));
       },
       cancelOnError: true);
     return future;
   }
 }
 
 /**
  * A control object for the subscription on a [Stream].
  *
  * When you subscribe on a [Stream] using [Stream.listen],
@@ skipping 401 matching lines @@
    *
    * If a [moveNext] call has been made, it will complete with `false` as value,
    * as will all further calls to [moveNext].
    *
    * If you need to stop listening for values before the stream iterator is
    * automatically closed, you must call [cancel] to ensure that the stream
    * is properly closed.
    */
   void cancel();
 }