php 根据函数名找到定义位置

function function_dump($funcname) {
try {
    if(is_array($funcname)) {
        $func = new ReflectionMethod($funcname[0], $funcname[1]);
        $funcname = $funcname[1];
    } else {
        $func = new ReflectionFunction($funcname);
    }
} catch (ReflectionException $e) {
    echo $e->getMessage();
return;
}
$start = $func->getStartLine() - 1;
$end =  $func->getEndLine() - 1;
$filename = $func->getFileName();
echo "function $funcname defined by $filename($start - $end)
";
}