I'm not familair with regular expressions. I'm trying to understand it, but it's difficult.
I've got a regular expression which will wrap any URL in an anchor tag. However, it's also wrapping URLs which are already in an anchor tag. I would like to prevent that, so I found a regular expression which does this for me.
?![^<]*</a>
However, I have no idea how I would add this to my existing regular expression. This is my current regular expression:
preg_replace('!(((ht)tp(s)?://)[-a-zA-Zа-яА-Я()0-9#:%_+.~#?&;//=]+)!i', '$1', $text); ?>
So, how can I skip an URL that is already wrapped in an anchor tag?
I'm gonna join the choir and say: Don't use regex for this - use a html parser.
This said - the regex you found isn't really a regex in itself. It's part of a negative look-ahead that kind of checks you aren't in an anchor. (It should really be (?![^<]*</a>).) It checks that following text up to the next < (or the end) isn't followed by </>.
Appending this to the en of your original RE will sometimes do the trick. I won't spend time thinking of situations it'll fail - but it probably will.
Along with some simplifications your regex should look like this:
(https?:\/\/[-\wа-яА-Я()#:%+.~#?&;\/=]+)(?![^<]*<\/a>)
This probably will work for you mostly, but probably will fail at times as well.
Regards
Related
I am making a preg_replace on html page. My pattern is aimed to add surrounding tag to some words in html. However, sometimes my regular expression modifies html tags. For example, when I try to replace this text:
yasar
So that yasar reads <span class="selected-word">yasar</span> , my regular expression also replaces yasar in alt attribute of anchor tag. Current preg_replace() I am using looks like this:
preg_replace("/(asf|gfd|oyws)/", '<span class=something>${1}</span>',$target);
How can I make a regular expression, so that it doesn't match anything inside a html tag?
You can use an assertion for that, as you just have to ensure that the searched words occur somewhen after an >, or before any <. The latter test is easier to accomplish as lookahead assertions can be variable length:
/(asf|foo|barr)(?=[^>]*(<|$))/
See also http://www.regular-expressions.info/lookaround.html for a nice explanation of that assertion syntax.
Yasar, resurrecting this question because it had another solution that wasn't mentioned.
Instead of just checking that the next tag character is an opening tag, this solution skips all <full tags>.
With all the disclaimers about using regex to parse html, here is the regex:
<[^>]*>(*SKIP)(*F)|word1|word2|word3
Here is a demo. In code, it looks like this:
$target = "word1 <a skip this word2 >word2 again</a> word3";
$regex = "~<[^>]*>(*SKIP)(*F)|word1|word2|word3~";
$repl= '<span class="">\0</span>';
$new=preg_replace($regex,$repl,$target);
echo htmlentities($new);
Here is an online demo of this code.
Reference
How to match pattern except in situations s1, s2, s3
How to match a pattern unless...
This might be the kind of thing that you're after: http://snipplr.com/view/3618/
In general, I'd advise against such. A better alternative is to strip out all HTML tags and instead rely on BBcode, such as:
[b]bold text[b] [i]italic text[i]
However I appreciate that this might not work well with what you're trying to do.
Another option may be HTML Purifier, see: http://htmlpurifier.org/
From top of my mind, this should be working:
echo preg_replace("/<(.*)>(.*)<\/(.*)>/i","<$1><span class=\"some-class\">$2</span></$3>",$target);
But, I don't know how safe this would be. I am just presenting a possibility :)
I am using this regular expression to filter .pdffiles from the webpage:
$regex='|<a.*?href="(.*pdf?)"|';
It does the job if the link is like this:
www.xyz.com/trgrrtr/ghtty.pdf
but if the links are something like this, it is unable to filter:
www.xyz.com/trgrrtr/ghtty.pdf?code=KksRHhdVXAoECBFCVFpeXBsBUgYMDQpxd3J2d3F2fDtzfnFuLiErNXNpIG5kYm16aGhpcmxoa05QV1VKUVFFUxQ%3D
What regular expression I should use to filter out this link from a webpage?
First of all, you need to escape the ? otherwise it just makes the f in front of it optional. Then you could do something like this:
$regex = '|<a.*?href="([^"]*\.pdf\?[^"]*)"|';
The use of the negated character class makes sure that you cannot leave the attribute. (.* could consume the attribute-ending " as well, and go on until " matches another double quote further down the string.)
But I really recommend that you use a DOM parser to find the link-elements first. PHP has a built-in one and there is a very nice and convenient 3rd-party alternative.
The blog post An Improved Liberal, Accurate Regex Pattern for Matching URLs may help.
I am making a preg_replace on html page. My pattern is aimed to add surrounding tag to some words in html. However, sometimes my regular expression modifies html tags. For example, when I try to replace this text:
yasar
So that yasar reads <span class="selected-word">yasar</span> , my regular expression also replaces yasar in alt attribute of anchor tag. Current preg_replace() I am using looks like this:
preg_replace("/(asf|gfd|oyws)/", '<span class=something>${1}</span>',$target);
How can I make a regular expression, so that it doesn't match anything inside a html tag?
You can use an assertion for that, as you just have to ensure that the searched words occur somewhen after an >, or before any <. The latter test is easier to accomplish as lookahead assertions can be variable length:
/(asf|foo|barr)(?=[^>]*(<|$))/
See also http://www.regular-expressions.info/lookaround.html for a nice explanation of that assertion syntax.
Yasar, resurrecting this question because it had another solution that wasn't mentioned.
Instead of just checking that the next tag character is an opening tag, this solution skips all <full tags>.
With all the disclaimers about using regex to parse html, here is the regex:
<[^>]*>(*SKIP)(*F)|word1|word2|word3
Here is a demo. In code, it looks like this:
$target = "word1 <a skip this word2 >word2 again</a> word3";
$regex = "~<[^>]*>(*SKIP)(*F)|word1|word2|word3~";
$repl= '<span class="">\0</span>';
$new=preg_replace($regex,$repl,$target);
echo htmlentities($new);
Here is an online demo of this code.
Reference
How to match pattern except in situations s1, s2, s3
How to match a pattern unless...
This might be the kind of thing that you're after: http://snipplr.com/view/3618/
In general, I'd advise against such. A better alternative is to strip out all HTML tags and instead rely on BBcode, such as:
[b]bold text[b] [i]italic text[i]
However I appreciate that this might not work well with what you're trying to do.
Another option may be HTML Purifier, see: http://htmlpurifier.org/
From top of my mind, this should be working:
echo preg_replace("/<(.*)>(.*)<\/(.*)>/i","<$1><span class=\"some-class\">$2</span></$3>",$target);
But, I don't know how safe this would be. I am just presenting a possibility :)
I'm trying to write a regular expression for matching the following HTML.
<span class="hidden_text">Some text here.</span>
I'm struggling to write out the condition to match it and have tried the following, but in some cases it selects everything after the span as well.
$condition = "/<span class=\"hidden_text\">(.*)<\/span>/";
If anyone could highlight what I'm doing wrong that would be great.
You need to use a non-greedy selection by adding ? after .* :
$condition = "/<span class=\"hidden_text\">(.*?)<\/span>/";
Note : If you need to match generic HTML, you should use a XML parser like DOM.
You shouldn’t try to use regular expressions on a non-regular language like HTML. Better use a proper HTML parser to parse the document.
See the following questions for further information on how to do that with PHP:
How to parse HTML with PHP?
Best methods to parse HTML
$condition = "/<span class=\"hidden_text\">(?<=^|>)[^><]+?(?=<|$)<\/span>/";
I got it. ;)
Chances are that you have multiple spans, and the regexp you're using will default to greedy mode
It's a lot easier using PHP's DOM Parser to extract content from HTML
I think this is what they call a teachable moment. :P Let us now compare and contrast the regex in your self-answer:
"/<span class=\"hidden_text\">(?<=^|>)[^><]+?(?=<|$)<\/span>/"
...and this one:
'~<span class="hidden_text">[^><]++</span>~'
PHP's double-quoted strings are subject to interpolation of embedded variables ($my_var) and evaluation of source code wrapped in braces ({return "foo"}). If you aren't using those features, it's best to use single-quoted strings to avoid surprises. As a bonus, you don't have to escape those double-quotes any more.
PHP allows you to use almost any ASCII punctuation character for the regex delimiters. By replacing your slashes with ~ I eliminated the need to escape the slash in the closing tag.
The lookbehind - (?<=^|>) - was not doing anything useful. It would only ever be evaluated immediately after the opening tag had been matched, so the previous character was always >.
[^><]+? is good (assuming you don't want to allow other tags in the content), but the quantifier doesn't need to be reluctant. [^><]+ can't possibly overrun the closing </span> tag, so there's point sneaking up on it. In fact, go ahead and kick the door in with a possessive quantifier: [^><]++.
Like the lookbehind before it, (?=<|$) was only taking up space. If [^><]+ consumes everything it can and the next character not <, you don't need a lookahead to tell you the match is going to fail.
Note that I'm just critiquing your regex, not fixing it; your regex and mine would probably yield the same results every time. There are many ways both of them can go wrong, even if the HTML you're working with is perfectly valid. Matching HTML with regexes is like trying to catch a greased pig.
I have a load of user-submitted content. It is HTML, and may contain URLs. Some of them will be <a>'s already (if the user is good) but sometimes users are lazy and just type www.something.com or at best http://www.something.com.
I can't find a decent regex to capture URLs but ignore ones that are immediately to the right of either a double quote or '>'. Anyone got one?
Jan Goyvaerts, creator of RegexBuddy, has written a response to Jeff Atwood's blog that addresses the issues Jeff had and provides a nice solution.
\b(?:(?:https?|ftp|file)://|www\.|ftp\.)[-A-Z0-9+&##/%=~_|$?!:,.]*[A-Z0-9+&##/%=~_|$]
In order to ignore matches that occur right next to a " or >, you could add (?<![">]) to the start of the regex, so you get
(?<![">])\b(?:(?:https?|ftp|file)://|www\.|ftp\.)[-A-Z0-9+&##/%=~_|$?!:,.]*[A-Z0-9+&##/%=~_|$]
This will match full addresses (http://...) and addresses that start with www. or ftp. - you're out of luck with addresses like ars.userfriendly.org...
This thread is old as the hills, but I came across it while working on my own problem: That is, convert any urls into links, but leave alone any that are already within anchor tags. After a while, this is what has popped out:
(?!(?!.*?<a)[^<]*<\/a>)(?:(?:https?|ftp|file)://|www\.|ftp\.)[-A-Z0-9+&#/%=~_|$?!:,.]*[A-Z0-9+&#/%=~_|$]
With the following input:
http://www.google.com
http://google.com
www.google.com
<p>http://www.google.com<p>
this is a normal sentence. let's hope it's ok.
www.google.com
This is the output of a preg_replace:
http://www.google.com
http://google.com
www.google.com
<p>http://www.google.com<p>
this is a normal sentence. let's hope it's ok.
www.google.com
Just wanted to contribute back to save somebody some time.
I made a slight modification to the Regex contained in the original answer:
(?<![.*">])\b(?:(?:https?|ftp|file)://|[a-z]\.)[-A-Z0-9+&#/%=~_|$?!:,.]*[A-Z0-9+&#/%=~_|$]
which allows for more subdomains, and also runs a more full check on tags. To apply this to PHP's preg replace, you can use:
$convertedText = preg_replace( '#(?<![.*">])\b(?:(?:https?|ftp|file)://|[a-z]\.)[-A-Z0-9+&#/%=~_|$?!:,.]*[A-Z0-9+&#/%=~_|$]#i', '\0', $originalText );
Note, I removed # from the regex, in order to use it as a delimiter for preg_replace. It's pretty rare that # would be used in a URL anyway.
Obviously, you can modify the replacement text, and remove target="_blank", or add rel="nofollow" etc.
Hope that helps.
To skip existing ones just use a look-behind - add (?<!href=") to the beginning of your regular expression, so it would look something like this:
/(?<!href=")http://\S*/
Obviously this isn't a complete solution for finding all types of URLs, but this should solve your problem of messing with existing ones.
if (preg_match('/\b(?<!=")(https?|ftp|file):\/\/[-A-Z0-9+&##\/%?=~_|!:,.;]*[A-Z0-9+&##\/%=~_|](?!.*".*>)(?!.*<\/a>)/i', $subject)) {
# Successful match
} else {
# Match attempt failed
}
Shameless plug: You can look here (regular expression replace a word by a link) for inspiration.
The question asked to replace some word with a certain link, unless there already was a link. So the problem you have is more or less the same thing.
All you need is a regex that matches a URL (in place of the word). The simplest assumption would be like this: An URL (optionally) starts with "http://", "ftp://" or "mailto:" and lasts as long as there are no white-space characters, line breaks, tag brackets or quotes).
Beware, long regex ahead. Apply case-insensitively.
(href\s*=\s*['"]?)?((?:http://|ftp://|mailto:)?[^.,<>"'\s\r\n\t]+(?:\.(?![.<>"'\s\r\n])[^.,!<>"'\s\r\n\t]+)+)
Be warned - this will also match URLs that are technically invalid, and it will recognize things.formatted.like.this as an URL. It depends on your data if it is too insensitive. I can fine-tune the regex if you have examples where it returns false positives.
The regex will produce two match groups. Group 2 will contain the matched thing, which is most likely an URL. Group 1 will either contain an empty string or an 'href="'. You can use it as an indicator that this match occurred inside a href parameter of an existing link and you don't have to do touch that one.
Once you confirm that this does the right thing for you most of the time (with user supplied data, you can never be sure), you can do the rest in two steps, as I proposed it in the other question:
Make a link around every URL there is (unless there is something in match group 1!) This will produce double nested <a> tags for things that have a link already.
Scan for incorrectly nested <a> tags, removing the innermost one