Retwis ported to modern Redis data types.

The example (and related documentation at redis.io) was not updated for
5 years. Redis had no sorted sets and hashes when the original code was
written (!). An update was really needed.

We also use a modern PHP client now: Predis. A copy is shipped within
this repository to make life easier to newcomers trying Redis for the
first time via this example.

Predis/Command/ZSetRangeByScore.php

@@ -0,0 +1,67 @@
+<?php
+
+/*
+ * This file is part of the Predis package.
+ *
+ * (c) Daniele Alessandri <suppakilla@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Predis\Command;
+
+/**
+ * @link http://redis.io/commands/zrangebyscore
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+class ZSetRangeByScore extends ZSetRange
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function getId()
+    {
+        return 'ZRANGEBYSCORE';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function prepareOptions($options)
+    {
+        $opts = array_change_key_case($options, CASE_UPPER);
+        $finalizedOpts = array();
+
+        if (isset($opts['LIMIT']) && is_array($opts['LIMIT'])) {
+            $limit = array_change_key_case($opts['LIMIT'], CASE_UPPER);
+
+            $finalizedOpts[] = 'LIMIT';
+            $finalizedOpts[] = isset($limit['OFFSET']) ? $limit['OFFSET'] : $limit[0];
+            $finalizedOpts[] = isset($limit['COUNT']) ? $limit['COUNT'] : $limit[1];
+        }
+
+        return array_merge($finalizedOpts, parent::prepareOptions($options));
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function withScores()
+    {
+        $arguments = $this->getArguments();
+
+        for ($i = 3; $i < count($arguments); $i++) {
+            switch (strtoupper($arguments[$i])) {
+                case 'WITHSCORES':
+                    return true;
+
+                case 'LIMIT':
+                    $i += 2;
+                    break;
+            }
+        }
+
+        return false;
+    }
+}