titanscssc::callBuiltin PHP Method

    protected function callBuiltin($name, $args, &$returnValue)
    {
        // try a lib function
        $name = $this->normalizeName($name);
        $libName = "lib_" . $name;
        $f = array($this, $libName);
        $prototype = isset(self::${$libName}) ? self::${$libName} : null;
        if (is_callable($f)) {
            $sorted = $this->sortArgs($prototype, $args);
            foreach ($sorted as &$val) {
                $val = $this->reduce($val, true);
            }
            $returnValue = call_user_func($f, $sorted, $this);
        } elseif (isset($this->userFunctions[$name])) {
            // see if we can find a user function
            $fn = $this->userFunctions[$name];
            foreach ($args as &$val) {
                $val = $this->reduce($val[1], true);
            }
            $returnValue = call_user_func($fn, $args, $this);
        }
        if (isset($returnValue)) {
            // coerce a php value into a scss one
            if (is_numeric($returnValue)) {
                $returnValue = array('number', $returnValue, "");
            } elseif (is_bool($returnValue)) {
                $returnValue = $returnValue ? self::$true : self::$false;
            } elseif (!is_array($returnValue)) {
                $returnValue = array('keyword', $returnValue);
            }
            return true;
        }
        return false;
    }