Merge pull request #9 from nathan7/fix-delegation

Fix delegation

Author: ForbesLindesay

index.js

@@ -6,8 +6,8 @@ function Promise(fn) {
   if (!(this instanceof Promise)) return new Promise(fn)
   if (typeof fn !== 'function') throw new TypeError('not a function')
   var state = null
+    , delegating = false
     , value = null
-    , resolved = false
     , deferreds = []
 
   this.then = function(onFulfilled, onRejected) {
@@ -40,10 +40,17 @@ function Promise(fn) {
   }
 
   function resolve(newValue) {
+    if (delegating)
+      return
+    resolve_(newValue)
+  }
+
+  function resolve_(newValue) {
     if (state !== null)
       return
     if (isPromise(newValue)) {
-      newValue.then(resolve, reject)
+      delegating = true
+      newValue.then(resolve_, reject_)
       return
     }
     state = true
@@ -52,6 +59,12 @@ function Promise(fn) {
   }
 
   function reject(newValue) {
+    if (delegating)
+      return
+    reject_(newValue)
+  }
+
+  function reject_(newValue) {
     if (state !== null)
       return
     state = false
@@ -65,14 +78,6 @@ function Promise(fn) {
     deferreds = null
   }
 
-  function ifUnResolved(fn) {
-    return function (value) {
-      if (resolved) return
-      resolved = true
-      return fn(value)
-    }
-  }
-
-  try { fn(ifUnResolved(resolve), ifUnResolved(reject)) }
-  catch(e) { ifUnResolved(reject)(e) }
+  try { fn(resolve, reject) }
+  catch(e) { reject(e) }
 }