--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Implab/Deferred`1.cs	Fri Jan 26 11:19:38 2018 +0300
@@ -0,0 +1,48 @@
+using System;
+using System.Diagnostics;
+
+namespace Implab {
+    public class Deferred<T> : IResolvable<T> {
+        readonly AbstractPromise<T> m_promise;
+        readonly IDispatcher m_dispatcher;
+
+        internal Deferred(AbstractPromise<T> promise, IDispatcher dispatcher) {
+            Debug.Assert(promise != null);
+            m_promise = promise;
+            m_dispatcher = dispatcher;
+        }
+
+        public IPromise<T> Promise {
+            get { return m_promise; }
+        }
+
+        public void Reject(Exception error) {
+            m_promise.Reject(error);
+        }
+
+        public void Resolve(T value) {
+            m_promise.Resolve(value);
+        }
+
+        public void Resolve(IPromise<T> thenable) {
+            if (thenable == null)
+                Reject(new Exception("The promise or task are expected"));
+            if (thenable == m_promise)
+                Reject(new Exception("The promise cannot be resolved with oneself"));
+
+            else if (m_dispatcher != null)
+                // dispatch (see ecma-262/6.0: 25.4.1.3.2 Promise Resolve Functions)
+                m_dispatcher.Enqueue(() => Chain(thenable));
+            else
+                Chain(thenable);
+        }
+
+        void Chain(IPromise<T> thenable) {
+            try {
+                thenable.Then(this);
+            } catch (Exception err) {
+                Reject(err);
+            }
+        }
+    }
+}
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