如何将翻译解析添加到rain.tpl？

I'm not good with regular expressions and I met huge problems with changing rain.tpl class. Whole class is available here (I don't want to copy-paste whole file here).

The thing is that I'd like to parse {_(word)} into <?= __('word') ?> because it's a lot easier to use than {function="__('word')"}.

I tried to change it myself but I can't put proper regular expressions into methods and output are more and more errors.

EDIT:
The part of parsing function responsible for parsing {function="__('word')"} etc looks like this:

//function
elseif( preg_match( '/\{function="(\w*)(.*?)"\}/', $html, $code ) ){

    //tag
    $tag = $code[ 0 ];

    //function
    $function = $code[ 1 ];

    // check if there's any function disabled by black_list
    $this->function_check( $tag );

    if( empty( $code[ 2 ] ) )
        $parsed_function = $function . "()";
    else
        // parse the function
        $parsed_function = $function . $this->var_replace( $code[ 2 ], $tag_left_delimiter = null, $tag_right_delimiter = null, $php_left_delimiter = null, $php_right_delimiter = null, $loop_level );

    //if code
    $compiled_code .=   "<?php echo $parsed_function; ?>";
}

And the functions that calls the parsing (there are some regular expressions too) look like it:

protected function compileTemplate( $template_code, $tpl_basedir ){

    //tag list
    $tag_regexp = array( 'loop'         => '(\{loop(?: name){0,1}="\${0,1}[^"]*"\})',
                         'loop_close'   => '(\{\/loop\})',
                         'if'           => '(\{if(?: condition){0,1}="[^"]*"\})',
                         'elseif'       => '(\{elseif(?: condition){0,1}="[^"]*"\})',
                         'else'         => '(\{else\})',
                         'if_close'     => '(\{\/if\})',
                         'function'     => '(\{function="[^"]*"\})',
                         'noparse'      => '(\{noparse\})',
                         'noparse_close'=> '(\{\/noparse\})',
                         'ignore'       => '(\{ignore\}|\{\*)',
                         'ignore_close' => '(\{\/ignore\}|\*\})',
                         'include'      => '(\{include="[^"]*"(?: cache="[^"]*")?\})',
                         'template_info'=> '(\{\$template_info\})',
                         'function'     => '(\{function="(\w*?)(?:.*?)"\})'
                        );

    $tag_regexp = "/" . join( "|", $tag_regexp ) . "/";

    //split the code with the tags regexp
    $template_code = preg_split ( $tag_regexp, $template_code, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );

    //path replace (src of img, background and href of link)
    $template_code = $this->path_replace( $template_code, $tpl_basedir );

    //compile the code
    $compiled_code = $this->compileCode( $template_code );

    //return the compiled code
    return $compiled_code;

}

Hope it's enough for you to help me without downloading and reading the whole class file. Hope someone knows this template and can help me :)

By the time of waiting I managed to find the solution by myself. Here it is:

1. I added the line 'translation' => '(\{_\([^)]*(\w*)\)\})', to the array $tag_regexp
2. I added the new elseif:

//translation
            elseif( preg_match( '/\{_\((\w*)\)\}/', $html, $code ) ){

                //function
                $word = $code[ 1 ];

                //if code
                $compiled_code .=   "<?= __('$word'); ?>";
            }

Maybe it will help someone :)