Question

I need a regex (to work in PHP) to replace American English words in HTML with British English words. So color would be replaced by colour, meters by metres and so on [I know that meters is also a British English word, but for the copy we’ll be using it will always be referring to units of distance rather than measuring devices]. The pattern would need to work accurately in the following (slightly contrived) examples (although as I have no control over the actual input these could exist):

<span style="color:red">This is the color red</span>

[should not replace color in the HTML tag but should replace it in the sentence]

<p>Color: red</p>

[should replace word]

<p>Tony Brammeter lives 2000 meters from his sister</p>

[should replace meters for the word but not in the name]

I know there are edge cases where replacement wouldn’t be useful (if his name was Tony Meter for example), but these are rare enough that we can deal with them when they come up.

Answer 1

Html/xml should not be processed with regular expressions, it is really hard to generate one that will match anything. But you can use the builtin dom extension and process your string recursively:

# Warning: untested code!
function process($node, $replaceRules) {
    foreach ($node->children as $childNode) {
        if ($childNode instanceof DOMTextNode) {
            $text = pre_replace(
                array_keys(replaceRules),
                array_values($replaceRules),
                $childNode->wholeText
            );
            $node->replaceChild($childNode, new DOMTextNode($text));
        } else {
            process($childNode, $replaceRules);
        }
    }
}
$replaceRules = array(
    '/\bcolor\b/i' => 'colour',
    '/\bmeter\b/i' => 'metre',
);
$doc = new DOMDocument();
$doc->loadHtml($htmlString);
process($doc, $replaceRules);
$htmlString = $doc->saveHTML();