php自动转换URL，跳转至超链接

在WordPress中，如果你想自动转换URL，跳转至超链接页面，你可以利用内置的函数make_clickable()执行此操作。如果你想基于WordPress之外操作该程序，那么你可以参考wp-includes/formatting.php源代码。

function _make_url_clickable_cb($matches) {
$ret = '';
$url = $matches[2];

if ( empty($url) )
return $matches[0];
// removed trailing [.,;:] from URL
if ( in_array(substr($url, -1), array('.', ',', ';', ':')) === true ) {
$ret = substr($url, -1);
$url = substr($url, 0, strlen($url)-1);
}
return $matches[1] . "<a href=\"$url\" rel=\"nofollow\">$url</a>" . $ret;
}

function _make_web_ftp_clickable_cb($matches) {
$ret = '';
$dest = $matches[2];
$dest = 'http://' . $dest;

if ( empty($dest) )
return $matches[0];
// removed trailing [,;:] from URL
if ( in_array(substr($dest, -1), array('.', ',', ';', ':')) === true ) {
$ret = substr($dest, -1);
$dest = substr($dest, 0, strlen($dest)-1);
}
return $matches[1] . "<a href=\"$dest\" rel=\"nofollow\">$dest</a>" . $ret;
}

function _make_email_clickable_cb($matches) {
$email = $matches[2] . '@' . $matches[3];
return $matches[1] . "<a href=\"mailto:$email\">$email</a>";
}

function make_clickable($ret) {
$ret = ' ' . $ret;
// in testing, using arrays here was found to be faster
$ret = preg_replace_callback('#([\s>])([\w]+?://[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_url_clickable_cb', $ret);
$ret = preg_replace_callback('#([\s>])((www|ftp)\.[\w\\x80-\\xff\#$%&~/.\-;:=,?@\[\]+]*)#is', '_make_web_ftp_clickable_cb', $ret);
$ret = preg_replace_callback('#([\s>])([.0-9a-z_+-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,})#i', '_make_email_clickable_cb', $ret);

// this one is not in an array because we need it to run last, for cleanup of accidental links within links
$ret = preg_replace("#(<a( [^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i", "$1$3</a>", $ret);
$ret = trim($ret);
return $ret;
}