I'm a bit out of my depth here, but I'm trying to let users write links, not entirely unlike how StackOverflow formats links.
Ideally, when a user enters [text to link here][23] in a text area, they will end up with text to link here when that information is written from the database to the page.
My part I'm failing is how to extract text to link and 23 from the matched pattern
This is the pattern I'm using, but a preg_replace using this will only allow me to replace the entire string, not operate on it. I might be mistaken in my use of preg_replace.
You can operate with preg_replace_callback, but even that is unnecessary:
preg_replace('/\[(.+?)\]\[(\d+)?\]/', '\1', $st);
This seems to be the trick you're looking for: ([[a-zA-Z0-9- ]+])([[0-9]+])
The parenthesis ( and ) are used for grouping...
Related
I like how StackOverflow allows you to search for tags by specifying [tagname] in the search field. How could I go about writing a parser that would help me separate out tags from normal text. I can think of the manual way which would be to use some combination of substring and/or regex to get the position of opening and closing square brackets, and then extract out those strings, but I'm curious if there's a better way (and my regex skill is subpar at best)
// example
$query = 'How to use [jQuery] [selector] selectors';
$tags = getTags($query); // $tags == 'jQuery, selector'
$text = getText($query); // $text == 'How to use selectors'
Regular Expressions are probably the way to go. The more you can specify about how the tags are set the easier it will be to capture the right ones (In the expression below I limit it to either letters \w or numbers \d. The function uses a capture group (enclosed in parens) to pull out the relevant tags.
function getTags($query) {
preg_match_all("/\[([\w\d]+)\]/", $query, $matches);
return $matches;
}
Regex would probably work best, just don't try to parse HTML.
https://www.debuggex.com/
Is a really good site for visually seeing what your regex string is doing. I would recommend reading up on the PHP regex functions, and learn some more, there is a cheatsheat at the bottom of the site.
.*[(tag)].*
Would work to get the tags, using a captured group. The preg_match_all function is really good for working with multiple results, just make sure to read the official documentation to get it working how you need it.
For parsing more complex, or irregular things (like html, which is extremely difficult to do reliably), it is better to do it manually. Regex has worked for all my non HTML parsing needs in the past.
I know there are other posts with a similar name but I've looked through them and they haven't helped me resolve this.
I'm trying to get my head around regex and preg_match. I am going through a body of text and each time a link exists I want it to be extracted. I'm currently using the following:
$reg_exUrl = "/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/\S*)?/";
which works fine until it finds one that has <br after it. Then I get the url plus the <br which means it doesn't work correctly. How can I have it so that it stops at the < without including it?
Also, I have been looking everywhere for a clear explanation of using regex and I'm still confused by it. Has anyone any good guides on it for future reference?
\S* is too broad. In particular, I could inject into your code with a URL like:
http://hax.hax/"><script>alert('HAAAAAAAX!');</script>
You should only allow characters that are allowed in URLs:
[-A-Za-z0-9._~:/?#[]#!$&'()*+,;=]*
Some of these characters are only allowed in specific places (such as ?) so if you want better validation you will need more cleverness
Instead of \S exclude the open tag char from the class:
$reg_exUrl = "/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/[^<]*)?/";
You might even want to be more restrictive by only allowing characters valid in URLs:
$reg_exUrl = "/(http|https|ftp|ftps)\:\/\/[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(\/[a-zA-Z_\-\.%\?&]*)?/";
(or some more characters)
You could use this one as presented on the:
http://regex101.com/r/zV1uI7
On the bottom of the site you got it explained step by step.
I have a custom markup parsing function that has been working very well for many years. I recently discovered a bug that I hadn't noticed before and I haven't been able to fix it. If anyone can help me with this that'd be awesome. So I have a custom built forum and text based MMORPG and every input is sanitized and parsed for bbcode like markup. It'll also parse out URL's and make them into legit links that go to an exit page with a disclaimer that you're leaving the site... So the issue that I'm having is that when I user posts multiple URL's in a text box (let's say \n delimited) it'll only convert every other URL into a link. Here's the parser for URL's:
$markup = preg_replace("/(^|[^=\"\/])\b((\w+:\/\/|www\.)[^\s<]+)" . "((\W+|\b)([\s<]|$))/ei", '"$1".shortURL("$2")."$4"', $markup);
As you can see it calls a PHP function, but that's not the issue here. Then entire text block is passed into this preg_replace at the same time rather than line by line or any other means.
If there's a simpler way of writing this preg_replace, please let me know
If you can figure out why this is only parsing every other URL, that's my ultimate goal here
Example INPUT:
http://skylnk.co/tRRTnb
http://skylnk.co/hkIJBT
http://skylnk.co/vUMGQo
http://skylnk.co/USOLfW
http://skylnk.co/BPlaJl
http://skylnk.co/tqcPbL
http://skylnk.co/jJTjRs
http://skylnk.co/itmhJs
http://skylnk.co/llUBAR
http://skylnk.co/XDJZxD
Example OUTPUT:
http://skylnk.co/tRRTnb
<br>http://skylnk.co/hkIJBT
<br>http://skylnk.co/vUMGQo
<br>http://skylnk.co/USOLfW
<br>http://skylnk.co/BPlaJl
<br>http://skylnk.co/tqcPbL
<br>http://skylnk.co/jJTjRs
<br>http://skylnk.co/itmhJs
<br>http://skylnk.co/llUBAR
<br>http://skylnk.co/XDJZxD
<br>
e flag in preg_replace is deprecated. You can use preg_replace_callback to access the same functionality.
i flag is useless here, since \w already matches both upper case and lower case, and there is no backreference in your pattern.
I set m flag, which makes the ^ and $ matches the beginning and the end of a line, rather than the beginning and the end of the entire string. This should fix your weird problem of matching every other line.
I also make some of the groups non-capturing (?:pattern) - since the bigger capturing groups have captured the text already.
The code below is not tested. I only tested the regex on regex tester.
preg_replace_callback(
"/(^|[^=\"\/])\b((?:\w+:\/\/|www\.)[^\s<]+)((?:\W+|\b)(?:[\s<]|$))/m",
function ($m) {
return "$m[1]".shortURL($m[2])."$m[3]";
},
$markup
);
Ok, so here's my issue:
I have a link, say: http://www.blablabla.com/watch?v=1lyu1KKwC74&feature=list_other&playnext=1&list=AL94UKMTqg-9CfMhPFKXPXcvJ_j65v7UuV
And the link is between two tags say like this:
<br>http://www.blablabla.com/watch?v=1lyu1KKwC74&feature=list_other&playnext=1&list=AL94UKMTqg-9CfMhPFKXPXcvJ_j65v7UuV<br></p>
Using this regex with preg_replace:
'#(^|[^\/]|[^>])('.addcslashes($link,'.?+').')([^\w\/]|[^<]$)#i'
As such:
preg_replace('#(^|[^\/]|[^>])('.addcslashes($link,'.?+').')([^\w\/]|[^<]$)#i', "***",$strText);
The resulted string is :
<br***p>
Which is wrong!!
It should have been
<br>***<br></p>
How can I get the desired result? I have blasted my head out trying to solve this one out.
I would like to mention that str_replace replaces even the link within another valid link, so it's not a good method, I need an exact match between two boundaries, even if the boundary is text or another HTML tag.
Assuming you don't want to use a DOM parser for some reason, I believe doing what you intended is as simple as the following:
preg_replace('#(^|[^\/]|[^>])('.addcslashes($link,'.?+').')([^\w\/]|[^<]$)#i', "$1***$3",$strText);
This uses $1 and $3 to put back the delimiting text you matched in your regular expression.
As others have pointed out, using a DOM parser is more reliable.
Does this do what you want?
I'm trying to put together a plug-in for vBulletin to filter out links to filesharing sites. But, as I'm sure you often hear, I'm a newb to php let alone regexes.
Basically, I'm trying to put together a regex and use a preg_replace to find any urls that are from these domains and replace the entire link with a message that they aren't allowed. I'd want it to find the link whether it's hyperlinked, posted as plain text, or enclosed in [CODE] bb tags.
As for regex, I would need it to find URLS with the following, I think:
Starts with http or an anchor tag. I believe that the URLS in [CODE] tags could be processed the same as the plain text URLS and it's fine if the replacement ends up inside the [CODE] tag afterward.
Could contain any number of any characters before the domain/word
Has the domain somewhere in the middle
Could contain any number of any characters after the domain
Ends with a number of extentions such as (html|htm|rar|zip|001) or in a closing anchor tag.
I have a feeling that it's numbers 2 and 4 that are tripping me up (if not much more). I found a similar question on here and tried to pick apart the code a bit (even though I didn't really understand it). I now have this which I thought might work, but it doesn't:
<?php
$filterthese = array('domain1', 'domain2', 'domain3');
$replacement = 'LINKS HAVE BEEN FILTERED MESSAGE';
$regex = array('!^http+([a-z0-9-]+\.)*$filterthese+([a-z0-9-]+\.)*(html|htm|rar|zip|001)$!',
'!^<a+([a-z0-9-]+\.)*$filterthese+([a-z0-9-]+\.)*</a>$!');
$this->post['message'] = preg_replace($regex, $replacement, $this->post['message']);
?>
I have a feeling that I'm way off base here, and I admit that I don't fully understand php let alone regexes. I'm open to any suggestions on how to do this better, how to just make it work, or links to RTM (though I've read up a bit and I'm going to continue).
Thanks.
You can use parse_url on the URLs and look into the hashmap it returns. That allows you to filter for domains or even finer-grained control.
I think you can avoid the overhead of this in using the filter_var built-in function.
You may use this feature since PHP 5.2.0.
$good_url = filter_var( filter_var( $raw_url, FILTER_SANITIZE_URL), FILTER_VALIDATE_URL);
Hmm, my first guess: You put $filterthese directly inside a single-quoted string. That single quotes don't allow for variable substitution. Also, the $filterthese is an array, that should first be joined:
var $filterthese = implode("|", $filterthese);
Maybe I'm way off, because I don't know anything about vBulletin plugins and their embedded magic, but that points seem worth a check to me.
Edit: OK, on re-checking your provided source, I think the regexp line should read like this:
$regex = '!(?#
possible "a" tag [start]: )(<a[^>]+href=["\']?)?(?#
offending link: )https?://(?#
possible subdomains: )(([a-z0-9-]+\.)*\.)?(?#
domains to block: )('.implode("|", $filterthese).')(?#
possible path: )(/[^ "\'>]*)?(?#
possible "a" tag [end]: )(["\']?[^>]*>)?!';