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/CommandInterface.php

@@ -0,0 +1,77 @@
+<?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;
+
+/**
+ * Defines an abstraction representing a Redis command.
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+interface CommandInterface
+{
+    /**
+     * Gets the ID of a Redis command.
+     *
+     * @return string
+     */
+    public function getId();
+
+    /**
+     * Set the hash for the command.
+     *
+     * @param int $hash Calculated hash.
+     */
+    public function setHash($hash);
+
+    /**
+     * Returns the hash of the command.
+     *
+     * @return int
+     */
+    public function getHash();
+
+    /**
+     * Sets the arguments for the command.
+     *
+     * @param array $arguments List of arguments.
+     */
+    public function setArguments(Array $arguments);
+
+    /**
+     * Sets the raw arguments for the command without processing them.
+     *
+     * @param array $arguments List of arguments.
+     */
+    public function setRawArguments(Array $arguments);
+
+    /**
+     * Gets the arguments of the command.
+     *
+     * @return array
+     */
+    public function getArguments();
+
+    /**
+     * Gets the argument of the command at the specified index.
+     *
+     * @param  int   $index Index of the desired argument.
+     * @return mixed
+     */
+    public function getArgument($index);
+
+    /**
+     * Parses a reply buffer and returns a PHP object.
+     *
+     * @param  string $data Binary string containing the whole reply.
+     * @return mixed
+     */
+    public function parseResponse($data);
+}