regex for a link

Question

I have a text with 'a' tags there. I have to add some new tags and attributes.

It looks like this:

'Some test <a href="site">here</a>. Yet <a href="site2">another</a> test.'

Now I have to get:

'Some test <noindex><a rel="nofollow" href="site">here</a></noindex>.'
'Yet <noindex><a rel="nofollow" href="site2">another</a></noindex> test.'

Any fast ways to do that with php? Thanks.

You can't parse [X]HTML with regex. But you can do regular expression replaces in PHP with well structured markup. It's a valid question. — David Snabel-Caunt, Sep 20 '11 at 22:10

Jacob Eggers · Accepted Answer · 2011-09-20T22:34:35.637

2

Something like this would cover most real world cases:

$text = 'Some test <a href="site">here</a>. Yet <a href="site2">another</a> test.';

$regex = '%(<a\s)(.*?</a>)%i';
$replacement = '<noindex>$1rel="nofollow" $2</noindex>';

preg_replace($regex, $replacement, $text);

edited Sep 20 '11 at 22:34

answered Sep 20 '11 at 22:17

Jacob Eggers

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score 1 · Answer 2 · answered Sep 20 '11 at 22:18

Bearing in mind that HTML parsing with regular expression is a bad idea (you should use something like DOMDocument instead), this should do it:

$str = 'Some test <a href="site">here</a>. Yet <a href="site2">another</a> test.';
echo preg_replace('/<a(.+?)<\/a>/', '<noindex><a$1</a></noindex>', $str);
// Some test <noindex><a href="site">here</a></noindex>. Yet <noindex><a href="site2">another</a></noindex> test.

score 1 · Answer 3 · answered Sep 20 '11 at 22:43

Just wanted to give the DOMDocument (docs) version, since the conventional wisdom says "Don't use RegEx on HTML!!". Well, that's a fine thing to say, but then what!? Well, here you go:

    // create a new DOMDocument
    $doc = new DOMDocument();

    // load the string into the DOM
    $doc->loadHTML('Some test <a href="site">here</a>. Yet <a href="site2">another</a> test.');

    // since we are working with HTML fragments here, remove <!DOCTYPE 
    $doc->removeChild($doc->firstChild);            

    // likewise remove <html><body></body></html> 
    $doc->replaceChild($doc->firstChild->firstChild->firstChild, $doc->firstChild);

    //Loop through each <a> tag in the dom and wrap it with <noindex>
    foreach($doc->getElementsByTagName('a') as $link) {
        $parent = $link->parentNode;
        $ni = $doc->createElement('noindex');
        $ni->appendChild($link->cloneNode(true));
        $parent->replaceChild($ni, $link);
    } 

   echo $doc->saveHTML();

Check it out here: http://codepad.org/ANi93sBj

score 0 · Answer 4 · answered Sep 20 '11 at 22:17

0

$string = preg_replace('~<a.*?href=(.*?)>(.*?)</a>~msi', '<noindex><a rel="nofollow" href=$1>$2</a></noindex>', $html);

answered Sep 20 '11 at 22:17

genesis

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regex for a link

4 Answers4