predis/lib/Predis/Commands/ScriptedCommand.php

<?php

namespace Predis\Commands;

abstract class ScriptedCommand extends ServerEval {
    public abstract function getScript();

    public abstract function keysCount();

    protected function filterArguments(Array $arguments) {
        if (($keys = $this->keysCount()) === -1) {
            $keys = count($arguments);
        }
        return array_merge(array($this->getScript(), $keys), $arguments);
    }
}