Auth_Yadis_ParseHTML::getMetaTags PHP Method

    function getMetaTags($html_string)
    {
        $html_string = preg_replace($this->_removed_re, "", $html_string);
        $key_tags = array($this->tagPattern('html', false, false), $this->tagPattern('head', false, false), $this->tagPattern('head', true, false), $this->tagPattern('html', true, false), $this->tagPattern(array('body', 'frameset', 'frame', 'p', 'div', 'table', 'span', 'a'), 'maybe', 'maybe'));
        $key_tags_pos = array();
        foreach ($key_tags as $pat) {
            $matches = array();
            preg_match($pat, $html_string, $matches, PREG_OFFSET_CAPTURE);
            if ($matches) {
                $key_tags_pos[] = $matches[0][1];
            } else {
                $key_tags_pos[] = null;
            }
        }
        // no opening head tag
        if (is_null($key_tags_pos[1])) {
            return array();
        }
        // the effective </head> is the min of the following
        if (is_null($key_tags_pos[2])) {
            $key_tags_pos[2] = strlen($html_string);
        }
        foreach (array($key_tags_pos[3], $key_tags_pos[4]) as $pos) {
            if (!is_null($pos) && $pos < $key_tags_pos[2]) {
                $key_tags_pos[2] = $pos;
            }
        }
        // closing head tag comes before opening head tag
        if ($key_tags_pos[1] > $key_tags_pos[2]) {
            return array();
        }
        // if there is an opening html tag, make sure the opening head tag
        // comes after it
        if (!is_null($key_tags_pos[0]) && $key_tags_pos[1] < $key_tags_pos[0]) {
            return array();
        }
        $html_string = substr($html_string, $key_tags_pos[1], $key_tags_pos[2] - $key_tags_pos[1]);
        $link_data = array();
        $link_matches = array();
        if (!preg_match_all($this->tagPattern('meta', false, 'maybe'), $html_string, $link_matches)) {
            return array();
        }
        foreach ($link_matches[0] as $link) {
            $attr_matches = array();
            preg_match_all($this->_attr_find, $link, $attr_matches);
            $link_attrs = array();
            foreach ($attr_matches[0] as $index => $full_match) {
                $name = $attr_matches[1][$index];
                $value = $this->replaceEntities($this->removeQuotes($attr_matches[2][$index]));
                $link_attrs[strtolower($name)] = $value;
            }
            $link_data[] = $link_attrs;
        }
        return $link_data;
    }