1 files changed, 37 insertions, 0 deletions
diff --git a/lib/memoize.js b/lib/memoize.js
new file mode 100644
index 0000000..30b989c
--- /dev/null
+++ b/lib/memoize.js
@@ -0,0 +1,37 @@
+'use strict';
+
+import identity from 'lodash/identity';
+import rest from 'lodash/rest';
+import has from 'lodash/has';
+
+import setImmediate from './internal/setImmediate';
+
+export default function memoize(fn, hasher) {
+    var memo = Object.create(null);
+    var queues = Object.create(null);
+    hasher = hasher || identity;
+    var memoized = rest(function memoized(args) {
+        var callback = args.pop();
+        var key = hasher.apply(null, args);
+        if (has(memo, key)) {
+            setImmediate(function() {
+                callback.apply(null, memo[key]);
+            });
+        } else if (has(queues, key)) {
+            queues[key].push(callback);
+        } else {
+            queues[key] = [callback];
+            fn.apply(null, args.concat([rest(function(args) {
+                memo[key] = args;
+                var q = queues[key];
+                delete queues[key];
+                for (var i = 0, l = q.length; i < l; i++) {
+                    q[i].apply(null, args);
+                }
+            })]));
+        }
+    });
+    memoized.memo = memo;
+    memoized.unmemoized = fn;
+    return memoized;
+}