XPath / PHP-与正则表达式匹配的特定标签的返回索引

Question

I'm trying to get the index of a tag which href matches certain regex, but whatever I try is throwing me a warning that says that the expression is invalid. Here's an example.

$dom = new DOMDocument();
$dom->loadHTML($html);
$url_check = testurl.com
$finder = new DomXPath($dom);

$finder->registerNamespace("php", "http://php.net/xpath");
$finder->registerPhpFunctions('preg_match');

//Updated to fix some errors, still invalid expression
$index = $finder->evaluate("count((/ol[@id='rso']/li[not(@id) and @class = 'g' and h3[@class='r']/a[php:function('preg_match','/^(http://|https://|ftp://)?(www(\d+)?.)?($url_check)\/?$/', string(@href) > 0)]])/preceding-sibling::*)");

$html is a string that stores the html of a webpage, which contains something like this

<ol id="wrap">
  <li class="list">
    <h3 class="j">
      <a href="http://xxxxxx.com">Not the one I'm trying to match</a>    
    </h3>
  </li>
  .
  .
  .
  <li class="list">
    <h3 class="j">
      <a href="http://testurl.com">Click here</a>    
    </h3>
  </li>
</ol>

Any suggestion is appreciated, and if you know a better/faster way to do this feel free to share :)

Answer 1

I found at least three problems in your expression :

• preceding-siblings should be singular, not plural
• the count() function has no ending parenthesis
• $url_check = testurl.com has no quotes (should trigger a syntax error).

fixed code :

$index = $finder->evaluate("count(/ol[@id='wrap']/li[@class = 'list']/h3[@class='j']/a[php:function('preg_match','/^(http://|https://|ftp://)?(www(\d+)?.)?($url_check)\/?$/', string(@href) > 0)]/preceding-sibling::li[@class='list'])");

Moreover, the example html code you give us doesn't provide any result for the expression (each <a> element has no siblings whatsoever). So, even with these fixes, the expression still returns 0 for your test case, which is normal