正则表达式匹配HTML标记不包含其他标记

Question

I am writing a regex find/replace that will insert a <span> into every <a href> in a file where a <span> does not already exist. It will allow other tags to be in the <a href> like <img>, <b>, etc.

Currently I have this regex:
Find: (<a[^>]+?style=".*?color:#(\w{6}).*?".*?>)(.+?)(<\/a>)
Replace: '$1<span style="color:#$2;">$3</span>$4'

It works great except if i run it over the same file, it will insert a <span> inside of a <span> and it gets messy.

Target Example:

We want it to ignore this:
<a href="http://mywebiste.com/link1.html" target="_blank" style="color:#bfbcba; text-decoration:underline;"><span style="color:#bfbcba;">Howdy</span></a>

But not this:
<a href="http://mywebiste.com/link1.html" target="_blank" style="color:#bfbcba; text-decoration:underline;">Howdy</a>

Or this:
<a href="http://mywebiste.com/link1.html" target="_blank" style="color:#bfbcba; text-decoration:underline;"><img src="myimg.gif" />Howdy</a>

--EDIT--

Using the PHP DOM library as suggested in the comments, this is what I have so far:

$doc = new DOMDocument();
$doc->loadHTML($input);
$tags = $doc->getElementsByTagName('a');
foreach ($tags as $tag) {
    $spancount = $tag->getElementsByTagName("span")->length;
    if($spancount == 0){
        $element = $doc->createElement('span');
        $tag->appendChild($element);
    }
}

echo $doc->saveHTML();`

Currently it will detect if there is a span inside an anchor and if there is, it will append a span to the inside of the anchor, however, i have yet to figure out how to get the original contents of the anchor inside the span.

Answer 1

Don't use regex for this, it's not ideal for HTML.

Use a DOM library and getElementsByTagName('a') then iterate through each anchor and see if it contains a sub span element with getElementsByTagName('span'), using the length property. If it doesn't, appendChild or assign the firstChild of the anchor node to your new span created with document.createElement('span').

EDIT: As for grabbing the inner html of the anchor, if there are lots of nodes inside, try using this:

<?php
function innerHTML($node){
  $doc = new DOMDocument();
  foreach ($node->childNodes as $child)
    $doc->appendChild($doc->importNode($child, true));

  return $doc->saveHTML();
}

$html = innerHTML( $anchorRef );

This may also help you out: Change innerHTML of a php DOMElement