举例：后台输入域名：www.onexin.net，前台输出的结果会自动变成http://开头的链接。
email也如此，都被自动识别并添加上了链接。
相关文件：/wp-includes/formatting.php
make_clickable函数
//开启文章识别网址,邮件地址 add_filter( 'the_content', 'make_clickable' );
/**
* Callback to convert URI match to HTML A element.
*
* This function was backported from 2.5.0 to 2.3.2. Regex callback for {@link
* make_clickable()}.
*
* @since 2.3.2
* @access private
*
* @param array $matches Single Regex Match.
* @return string HTML A element with URI address.
*/
function _make_url_clickable_cb($matches) {
$url = $matches[2];
$url = esc_url($url);
if ( empty($url) )
return $matches[0];
return $matches[1] . "<a href=\"$url\" rel=\"nofollow\">$url</a>";
}
/**
* Callback to convert URL match to HTML A element.
*
* This function was backported from 2.5.0 to 2.3.2. Regex callback for {@link
* make_clickable()}.
*
* @since 2.3.2
* @access private
*
* @param array $matches Single Regex Match.
* @return string HTML A element with URL address.
*/
function _make_web_ftp_clickable_cb($matches) {
$ret = '';
$dest = $matches[2];
$dest = 'http://' . $dest;
$dest = esc_url($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";
}
/**
* Callback to convert email address match to HTML A element.
*
* This function was backported from 2.5.0 to 2.3.2. Regex callback for {@link
* make_clickable()}.
*
* @since 2.3.2
* @access private
*
* @param array $matches Single Regex Match.
* @return string HTML A element with email address.
*/
function _make_email_clickable_cb($matches) {
$email = $matches[2] . '@' . $matches[3];
return $matches[1] . "<a href=\"mailto:$email\">$email</a>";
}
/**
* Convert plaintext URI to HTML links.
*
* Converts URI, www and ftp, and email addresses. Finishes by fixing links
* within links.
*
* @since 0.71
*
* @param string $ret Content to convert URIs.
* @return string Content with converted URIs.
*/
function make_clickable($ret) {
$ret = ' ' . $ret;
// in testing, using arrays here was found to be faster
$ret = preg_replace_callback('#(?<=[\s>])(\()?([\w]+?://(?:[\w\\x80-\\xff\#$%&~/=?@\[\](+-]|[.,;:](?![\s<]|(\))?([\s]|$))|(?(1)\)(?![\s<.,;:]|$)|\)))+)#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;
}
转载请注明出处：https://www.onexin.net/url-link-to-the-article-identified-wp/