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/AbstractCommand.php

@@ -0,0 +1,158 @@
+<?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;
+
+/**
+ * Base class for Redis commands.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+abstract class AbstractCommand implements CommandInterface
+{
+    private $hash;
+    private $arguments = array();
+
+    /**
+     * Returns a filtered array of the arguments.
+     *
+     * @param  array $arguments List of arguments.
+     * @return array
+     */
+    protected function filterArguments(Array $arguments)
+    {
+        return $arguments;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setArguments(Array $arguments)
+    {
+        $this->arguments = $this->filterArguments($arguments);
+        unset($this->hash);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setRawArguments(Array $arguments)
+    {
+        $this->arguments = $arguments;
+        unset($this->hash);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getArguments()
+    {
+        return $this->arguments;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getArgument($index)
+    {
+        if (isset($this->arguments[$index])) {
+            return $this->arguments[$index];
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setHash($hash)
+    {
+        $this->hash = $hash;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getHash()
+    {
+        if (isset($this->hash)) {
+            return $this->hash;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function parseResponse($data)
+    {
+        return $data;
+    }
+
+    /**
+     * Helper function used to reduce a list of arguments to a string.
+     *
+     * @param  string $accumulator Temporary string.
+     * @param  string $argument    Current argument.
+     * @return string
+     */
+    protected function toStringArgumentReducer($accumulator, $argument)
+    {
+        if (strlen($argument) > 32) {
+            $argument = substr($argument, 0, 32) . '[...]';
+        }
+
+        $accumulator .= " $argument";
+
+        return $accumulator;
+    }
+
+    /**
+     * Returns a partial string representation of the command with its arguments.
+     *
+     * @return string
+     */
+    public function __toString()
+    {
+        return array_reduce(
+            $this->getArguments(),
+            array($this, 'toStringArgumentReducer'),
+            $this->getId()
+        );
+    }
+
+    /**
+     * Normalizes the arguments array passed to a Redis command.
+     *
+     * @param  array $arguments Arguments for a command.
+     * @return array
+     */
+    public static function normalizeArguments(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.
+     *
+     * @param  array $arguments Arguments for a command.
+     * @return array
+     */
+    public static function normalizeVariadic(Array $arguments)
+    {
+        if (count($arguments) === 2 && is_array($arguments[1])) {
+            return array_merge(array($arguments[0]), $arguments[1]);
+        }
+
+        return $arguments;
+    }
+}