[php] UUID Class

<?php

/**
 * UUID class
 *
 * The following class generates VALID RFC 4122 COMPLIANT
 * Universally Unique IDentifiers (UUID) version 3, 4 and 5.
 *
 * UUIDs generated validates using OSSP UUID Tool, and output
 * for named-based UUIDs are exactly the same. This is a pure
 * PHP implementation.
 *
 * @author  Andrew Moore
 * @link    http://www.php.net/manual/en/function.uniqid.php#94959
 */
class UUID
{
    /**
     * Generate v3 UUID
     *
     * Version 3 UUIDs are named based. They require a namespace (another
     * valid UUID) and a value (the name). Given the same namespace and
     * name, the output is always the same.
     *
     * @param   string $namespace
     * @param   string $name
     *
     * @return  string
     */
    public static function v3($namespace, $name)
    {
        if (!self::isValid($namespace)) {
            return false;
        }

        // Get hexadecimal components of namespace
        $nhex = str_replace(array('-', '{', '}'), '', $namespace);

        // Binary Value
        $nstr = '';

        // Convert Namespace UUID to bits
        $len = strlen($nhex);
        for ($i = 0; $i < $len; $i += 2) {
            $nstr .= chr(hexdec($nhex[$i] . $nhex[$i + 1]));
        }

        // Calculate hash value
        $hash = md5($nstr . $name);

        return sprintf('%08s-%04s-%04x-%04x-%12s',

            // 32 bits for "time_low"
            substr($hash, 0, 8),

            // 16 bits for "time_mid"
            substr($hash, 8, 4),

            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 3
            (hexdec(substr($hash, 12, 4)) & 0x0fff) | 0x3000,

            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            (hexdec(substr($hash, 16, 4)) & 0x3fff) | 0x8000,

            // 48 bits for "node"
            substr($hash, 20, 12)
        );
    }

    /**
     * Generate v4 UUID
     *
     * Version 4 UUIDs are pseudo-random.
     *
     * @return  string
     */
    public static function v4()
    {
        return sprintf('%04x%04x-%04x-%04x-%04x-%04x%04x%04x',

            // 32 bits for "time_low"
            mt_rand(0, 0xffff),
            mt_rand(0, 0xffff),

            // 16 bits for "time_mid"
            mt_rand(0, 0xffff),

            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 4
            mt_rand(0, 0x0fff) | 0x4000,

            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            mt_rand(0, 0x3fff) | 0x8000,

            // 48 bits for "node"
            mt_rand(0, 0xffff),
            mt_rand(0, 0xffff),
            mt_rand(0, 0xffff)
        );
    }

    /**
     * Generate v5 UUID
     *
     * Version 5 UUIDs are named based. They require a namespace (another
     * valid UUID) and a value (the name). Given the same namespace and
     * name, the output is always the same.
     *
     * @param   string $namespace
     * @param   string $name
     *
     * @return  string
     */
    public static function v5($namespace, $name)
    {
        if (!self::isValid($namespace)) {
            return false;
        }

        // Get hexadecimal components of namespace
        $nhex = str_replace(array('-', '{', '}'), '', $namespace);

        // Binary Value
        $nstr = '';

        // Convert Namespace UUID to bits
        $len = strlen($nhex);
        for ($i = 0; $i < $len; $i += 2) {
            $nstr .= chr(hexdec($nhex[$i] . $nhex[$i + 1]));
        }

        // Calculate hash value
        $hash = sha1($nstr . $name);

        return sprintf('%08s-%04s-%04x-%04x-%12s',

            // 32 bits for "time_low"
            substr($hash, 0, 8),

            // 16 bits for "time_mid"
            substr($hash, 8, 4),

            // 16 bits for "time_hi_and_version",
            // four most significant bits holds version number 5
            (hexdec(substr($hash, 12, 4)) & 0x0fff) | 0x5000,

            // 16 bits, 8 bits for "clk_seq_hi_res",
            // 8 bits for "clk_seq_low",
            // two most significant bits holds zero and one for variant DCE1.1
            (hexdec(substr($hash, 16, 4)) & 0x3fff) | 0x8000,

            // 48 bits for "node"
            substr($hash, 20, 12)
        );
    }

    /**
     * Check whether speified UUID is valid
     *
     * @param   string $uuid
     *
     * @return  bool
     */
    public static function isValid($uuid)
    {
        return preg_match('/^\{?[0-9a-f]{8}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{4}\-?[0-9a-f]{12}\}?$/i', $uuid) === 1;
    }

    /**
     * Generate v4 UUID with stripped dashes
     *
     * @return  string
     */
    public static function generate()
    {
        return str_replace('-', null, self::v4());
    }
}