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/Helpers.php

@@ -0,0 +1,73 @@
+<?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;
+
+/**
+ * Defines a few helper methods.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ * @deprecated Deprecated since v0.8.3.
+ */
+class Helpers
+{
+    /**
+     * Offers a generic and reusable method to handle exceptions generated by
+     * a connection object.
+     *
+     * @deprecated Deprecated since v0.8.3 - moved in Predis\CommunicationException::handle()
+     * @param CommunicationException $exception Exception.
+     */
+    public static function onCommunicationException(CommunicationException $exception)
+    {
+        if ($exception->shouldResetConnection()) {
+            $connection = $exception->getConnection();
+
+            if ($connection->isConnected()) {
+                $connection->disconnect();
+            }
+        }
+
+        throw $exception;
+    }
+
+    /**
+     * Normalizes the arguments array passed to a Redis command.
+     *
+     * @deprecated Deprecated since v0.8.3 - moved in Predis\Command\AbstractCommand::normalizeArguments()
+     * @param  array $arguments Arguments for a command.
+     * @return array
+     */
+    public static function filterArrayArguments(Array $arguments)
+    {
+        if (count($arguments) === 1 && is_array($arguments[0])) {
+            return $arguments[0];
+        }
+
+        return $arguments;
+    }
+
+    /**
+     * Normalizes the arguments array passed to a variadic Redis command.
+     *
+     * @deprecated Deprecated since v0.8.3 - moved in Predis\Command\AbstractCommand::normalizeVariadic()
+     * @param  array $arguments Arguments for a command.
+     * @return array
+     */
+    public static function filterVariadicValues(Array $arguments)
+    {
+        if (count($arguments) === 2 && is_array($arguments[1])) {
+            return array_merge(array($arguments[0]), $arguments[1]);
+        }
+
+        return $arguments;
+    }
+}