From 060508a260a5c650f10f2ed38944f78c9406692a Mon Sep 17 00:00:00 2001
From: Graeme Yeates <yeatesgraeme@gmail.com>
Date: Thu, 17 Nov 2016 09:08:54 -0500
Subject: Implement array specific filter function

---
 lib/internal/filter.js | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/lib/internal/filter.js b/lib/internal/filter.js
index 34cd722..5af788c 100644
--- a/lib/internal/filter.js
+++ b/lib/internal/filter.js
@@ -1,12 +1,28 @@
 import arrayMap from 'lodash/_arrayMap';
+import isArrayLike from 'lodash/isArrayLike';
 import property from 'lodash/_baseProperty';
 import noop from 'lodash/noop';
-import once from './once';
 
-export default function _filter(eachfn, arr, iteratee, callback) {
-    callback = once(callback || noop);
-    var results = [];
+function filterArray(eachfn, arr, iteratee, callback) {
+    var truthValues = new Array(arr.length);
     eachfn(arr, function (x, index, callback) {
+        iteratee(x, function (err, v) {
+            truthValues[index] = !!v;
+            callback(err);
+        });
+    }, function (err) {
+        if (err) return callback(err);
+        var results = [];
+        for (var i = 0; i < arr.length; i++) {
+            if (truthValues[i]) results.push(arr[i]);
+        }
+        callback(null, results);
+    });
+}
+
+function filterGeneric(eachfn, coll, iteratee, callback) {
+    var results = [];
+    eachfn(coll, function (x, index, callback) {
         iteratee(x, function (err, v) {
             if (err) {
                 callback(err);
@@ -27,3 +43,8 @@ export default function _filter(eachfn, arr, iteratee, callback) {
         }
     });
 }
+
+export default function _filter(eachfn, coll, iteratee, callback) {
+    var filter = isArrayLike(coll) ? filterArray : filterGeneric;
+    filter(eachfn, coll, iteratee, callback || noop);
+}
-- 
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