Add support for ES2015 iteratorses6-iterators

2 files changed, 33 insertions, 19 deletions

diff --git a/.jshintrc b/.jshintrc
index 76be34a..72e53aa 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -19,6 +19,7 @@
     "sub": true,
     "browser": true,
     "node": true,
+    "esnext": true,
     "globals": {
         "self": true,
         "define": true,
diff --git a/lib/async.js b/lib/async.js
index a7743f5..b2c86ad 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -19,6 +19,7 @@
         return !v;
     }
 
+
     // global on the server, window in the browser
     var previous_async;
 
@@ -33,6 +34,8 @@
         previous_async = root.async;
     }
 
+    var iteratorSymbol = typeof Symbol == 'function' && Symbol.iterator;
+
     async.noConflict = function () {
         root.async = previous_async;
         return async;
@@ -131,22 +134,32 @@
         return keys;
     };
 
-    function _keyIterator(coll) {
+    function _iterator(coll) {
         var i = -1;
         var len;
         var keys;
+
         if (_isArrayLike(coll)) {
             len = coll.length;
             return function next() {
                 i++;
-                return i < len ? i : null;
+                return i < len ? [coll[i], i] : null;
             };
-        } else {
+        }
+        else if (iteratorSymbol && coll[iteratorSymbol]) {
+            var iterator = coll[iteratorSymbol]();
+            return function next() {
+                var item = iterator.next();
+                if (item.done) return null;
+                return _isArray(item.value) ? item.value : [item.value];
+            };
+        }
+        else {
             keys = _keys(coll);
             len = keys.length;
             return function next() {
                 i++;
-                return i < len ? keys[i] : null;
+                return i < len ? [coll[keys[i]], keys[i]] : null;
             };
         }
     }
@@ -225,12 +238,12 @@
         callback = _once(callback || noop);
         object = object || [];
 
-        var iter = _keyIterator(object);
-        var key, completed = 0;
+        var iter = _iterator(object);
+        var item, completed = 0;
 
-        while ((key = iter()) != null) {
+        while ((item = iter()) != null) {
             completed += 1;
-            iterator(object[key], key, only_once(done));
+            iterator(item[0], item[1], only_once(done));
         }
 
         if (completed === 0) callback(null);
@@ -242,7 +255,7 @@
             }
             // Check key is null in case iterator isn't exhausted
             // and done resolved synchronously.
-            else if (key === null && completed <= 0) {
+            else if (item === null && completed <= 0) {
                 callback(null);
             }
         }
@@ -252,20 +265,20 @@
     async.eachOfSeries = function (obj, iterator, callback) {
         callback = _once(callback || noop);
         obj = obj || [];
-        var nextKey = _keyIterator(obj);
-        var key = nextKey();
+        var iter = _iterator(obj);
+        var item = iter();
         function iterate() {
             var sync = true;
-            if (key === null) {
+            if (item === null) {
                 return callback(null);
             }
-            iterator(obj[key], key, only_once(function (err) {
+            iterator(item[0], item[1], only_once(function (err) {
                 if (err) {
                     callback(err);
                 }
                 else {
-                    key = nextKey();
-                    if (key === null) {
+                    item = iter();
+                    if (item === null) {
                         return callback(null);
                     } else {
                         if (sync) {
@@ -293,7 +306,7 @@
         return function (obj, iterator, callback) {
             callback = _once(callback || noop);
             obj = obj || [];
-            var nextKey = _keyIterator(obj);
+            var iter = _iterator(obj);
             if (limit <= 0) {
                 return callback(null);
             }
@@ -307,8 +320,8 @@
                 }
 
                 while (running < limit && !errored) {
-                    var key = nextKey();
-                    if (key === null) {
+                    var item = iter();
+                    if (item === null) {
                         done = true;
                         if (running <= 0) {
                             callback(null);
@@ -316,7 +329,7 @@
                         return;
                     }
                     running += 1;
-                    iterator(obj[key], key, only_once(function (err) {
+                    iterator(item[0], item[1], only_once(function (err) {
                         running -= 1;
                         if (err) {
                             callback(err);