Regex match full hyperlink only with certain class - php

Question

I have a string that has some hyperlinks inside. I want to match with regex only certain link from all of them. I can't know if the href or the class comes first, it may be vary.
This is for example a sting:
<div class='wp-pagenavi'>
<span class='pages'>Page 1 of 8</span><span class='current'>1</span>
<a href='http://stv.localhost/channel/political/page/2' class='page'>2</a>
»eee<span class='extend'>...</span><a href='http://stv.localhost/channel/political/page/8' class='last'>lastן »</a>
<a class="cccc">xxx</a>
</div>
I want to select from the aboce string only the one that has the class nextpostslink
So, the match in this example should return this -
»eee
This regex is the most close I could get -
/<a\s?(href=)?('|")(.*)('|") class=('|")nextpostslink('|")>.{1,6}<\/a>/
But it is selecting the links from the start of the string.
I think my problem is in the (.*) , but I can't figure out how to change this to select only the needed link.
I would appreciate your help.

Answer 1

It's much better to use a genuine HTML parser for this. Abandon all attempts to use regular expressions on HTML.
Use PHP's DOMDocument instead:
$dom = new DOMDocument;
$dom->loadHTML($yourHTML);
foreach ($dom->getElementsByTagName('a') as $link) {
$classes = explode(' ', $link->getAttribute('class'));
if (in_array('nextpostslink', $classes)) {
// $link has the class "nextpostslink"
}
}

Answer 2

Not sure if that's what you're but anyway: it's a bad idea to parse html with regex. Use a xpath implementation in order to reach the desired elements. The following xpath expression would give you all the 'a' elements with class "nextpostlink" :
//a[contains(#class,"nextpostslink")]
There are loads of xpath info around, since you didn't mention your programming language here goes a quick xpath tutorial using java: http://www.ibm.com/developerworks/library/x-javaxpathapi/index.html
Edit:
php + xpath + html: http://dev.juokaz.com/php/web-scraping-with-php-and-xpath

Answer 3

This would work in php:
/<a[^>]+href=(\"|')([^\"']*)('|\")[^>]+class=(\"|')[^'\"]*nextpostslink[^'\"]*('|\")[^>]*>(.{1,6})<\/a>/m
This is of course assuming that the class attribute always comes after the href attribute.
This is a code snippet:
$html = <<<EOD
<div class='wp-pagenavi'>
<span class='pages'>Page 1 of 8</span><span class='current'>1</span>
<a href='http://stv.localhost/channel/political/page/2' class='page'>2</a>
»eee<span class='extend'>...</span><a href='http://stv.localhost/channel/political/page/8' class='last'>lastן »</a>
<a class="cccc">xxx</a>
</div>
EOD;
$regexp = "/<a[^>]+href=(\"|')([^\"']*)('|\")[^>]+class=(\"|')[^'\"]*nextpostslink[^'\"]*('|\")[^>]*>(.{1,6})<\/a>/m";
$matches = array();
if(preg_match($regexp, $html, $matches)) {
echo "URL: " . $matches[2] . "\n";
echo "Text: " . $matches[6] . "\n";
}
I would however suggest first matching the link and then getting the url so that the order of the attributes doesn't matter:
<?php
$html = <<<EOD
<div class='wp-pagenavi'>
<span class='pages'>Page 1 of 8</span><span class='current'>1</span>
<a href='http://stv.localhost/channel/political/page/2' class='page'>2</a>
»eee<span class='extend'>...</span><a href='http://stv.localhost/channel/political/page/8' class='last'>lastן »</a>
<a class="cccc">xxx</a>
</div>
EOD;
$regexp = "/(<a[^>]+class=(\"|')[^'\"]*nextpostslink[^'\"]*('|\")[^>]*>(.{1,6})<\/a>)/m";
$matches = array();
if(preg_match($regexp, $html, $matches)) {
$link = $matches[0];
$text = $matches[4];
$regexp = "/href=(\"|')([^'\"]*)(\"|')/";
$matches = array();
if(preg_match($regexp, $html, $matches)) {
$url = $matches[2];
echo "URL: $url\n";
echo "Text: $text\n";
}
}
You could of course extend the regexp by matching one of the both variants (class first vs href first) but it would be very long and I don't think it would be a performance increase.
Just as a proof of concept I created a regexp that doesn't care about the order:
/<a[^>]+(href=(\"|')([^\"']*)('|\")[^>]+class=(\"|')[^'\"]*nextpostslink[^'\"]*(\"|')|class=(\"|')[^'\"]*nextpostslink[^'\"]*(\"|')[^>]+href=(\"|')([^\"']*)('|\"))[^>]*>(.{1,6})<\/a>/m
The text will be in group 12 and the URL will be in either group 3 or group 10 depending on the order.

Answer 4

As the question is to get it by regex, here is how <a\s[^>]*class=["|']nextpostslink["|'][^>]*>(.*)<\/a>.
It doesn't matter in which order are the attributs and it also consider simple or double quotes.
Check the regex online: https://regex101.com/r/DX03KD/1/

Answer 5

I replaced the (.*) with [^'"]+ as follows:
<a\s*(href=)?('|")[^'"]+('|") class=('|")nextpostslink('|")>.{1,6}</a>
Note: I tried this with RegEx Buddy so I didnt need to escape the <>'s or /