上原代码：

$sf_content = preg_replace_callback(
    "/(<script\s+.*?>.*?<\/script>)|(<a\s+.*?>.*?<\/a>)|(<img\s+.*?[\/]?>)|(\[attach\](\d+)\[\/attach\])/is",
    function($r) {
        return SF_inlink::base64_trans("encode", "<t_m_p>", (isset($r[1])?$r[1]:'').(isset($r[2])?$r[2]:'').(isset($r[3])?$r[3]:'').(isset($r[4])?$r[4]:''), "</t_m_p>");
    },
    $sf_content
);

错误原因就是这个$r导致的~囧，在PHP5.2中 未定义变量 导致这个使用preg_replace_callback出现的【unexpected T_FUNCTION 】错误

修改后的代码：

public static function replacea($matches) {
    return SF_inlink::base64_trans("encode", "<t_m_p>", (isset($matches[1])?$matches[1]:'').(isset($matches[2])?$matches[2]:'').(isset($matches[3])?$matches[3]:'').(isset($matches[4])?$matches[4]:''), "</t_m_p>");
}
public static function replaceb($matches) {
    return SF_inlink::base64_trans("decode", "", $matches[1], "");
}
public static function keywordaction($sf_content,$sf_tagstyle,$tag,$sf_onemaxnum){
    global $_G;
    $_G['SF_inlink_k_tmp'] = array();
    $matches = array();
    $sf_content = preg_replace_callback(
        "/(<script\s+.*?>.*?<\/script>)|(<a\s+.*?>.*?<\/a>)|(<img\s+.*?[\/]?>)|(\[attach\](\d+)\[\/attach\])/is", 
        array('SF_inlink', 'replacea'), 
        $sf_content
    );
    if(isset($sf_tagstyle)){
        $sf_content=preg_replace("/(".$tag->Name.")(?=[^<>]*<)/iU",'<a style="'.$sf_tagstyle.'" href="'.$tag->Url.'">${1}</a>',$sf_content,$sf_onemaxnum);
    }else{
        $sf_content=preg_replace("/(".$tag->Name.")(?=[^<>]*<)/iU",'<a href="'.$tag->Url.'">${1}</a>',$sf_content,$sf_onemaxnum);
    }
    $sf_content = preg_replace_callback(
        "/<t_m_p>(.*?)<\/t_m_p>/is", 
        array('SF_inlink', 'replaceb'),  
        $sf_content
    );
    return $sf_content;
}

此错误在PHP官方解释中也有说明

If you want to call non-static function inside your class, you can do something like this。 
For PHP 5.2 use second argument like array($this, 'replace')。
For PHP 5.3 use second argument like "self::replace"。