wip: underscore function related utils

Author: adhocore

src/Underscore.php

@@ -2,6 +2,54 @@
 
 namespace Ahc\Underscore;
 
-final class Underscore extends UnderscoreCollection
+final class Underscore extends UnderscoreArray
 {
+    public function bind(\Closure $fn, $ctx)
+    {
+        \Closure::bind($fn, \is_object($ctx) ? $ctx : null);
+    }
+
+    public function memoize(callable $fn)
+    {
+        static $memo = [];
+
+        $hash = \md5(\json_encode(\array_slice(\func_get_args(), 1)));
+
+        if (isset($memo[$hash])) {
+            return $memo[$hash];
+        }
+
+        return $memo[$hash] = \call_user_func_array($fn, $args);
+    }
+
+    public function delay(callable $fn, $wait)
+    {
+        usleep(1000 * $wait);
+
+        return \call_user_func_array($fn, \array_slice(\func_get_args(), 2));
+    }
+
+    public function throttle($fn, $wait)
+    {
+        $previous = 0;
+        $result   = null;
+
+        return function () use ($fn, &$previous, &$result, &$wait) {
+            $now  = $this->now();
+            $args = \func_get_args();
+
+            if (!$previous) {
+                $previous = $now;
+            }
+
+            $remaining = $wait - ($now - $previous);
+
+            if ($remaining <= 0 || $remaining > $wait) {
+                $previous = $now;
+                $result   = \call_user_func_array($fn, $args);
+            }
+
+            return $result;
+        };
+    }
 }