如何用带有小写标签的链接替换标签搜索结果？

Question

There is a text, for example:

> This is a Car

And a dynamic list of tags. For example:

c, car

Expected result is to get this after processing:

This is a <a href='car.ly?search=car'>Car</a>

So:

1. It should replace tags with links to search results to these tags
2. Longer tags should have prority over shorter tags
3. It should not replace tags inside "to phrase", for example "c" in "car.ly" etc.
4. search term should be lower case, and title letter case of the tag the same as the original
5. It should ommit tags and styling features in input text (it can contain HTML)

I have tested several solutions and no success with it. What is the proper way to handle this case? How to replace tags with a links to search results properly?

Answer 1

As far as I understand your question, I think you may want to use preg_replace_callback():

// A test string & some tags
$str = 'This is a Car c ar';
$tags = [ 'c', 'AR', 'car' ];

// sort tags by length
usort($tags, function ($a, $b) { return strlen($b)-strlen($a); });

// Then, replace tags one per one
foreach ($tags as $t) {

    // Will replace tag between whitespaces or start/end of string
    $str = preg_replace_callback('/(?<=\s|^)' . $t . '(?=\s|$)/i', function ($matches) {
        return '<a href="' . strtolower($matches[0]) . '.ly?search=' . strtolower($matches[0]) . '">' . $matches[0] . '</a>';
    }, $str);
}

Output:

<!-- echo $str; -->
This is a <a href="car.ly?search=car">Car</a> <a href="c.ly?search=c">c</a> <a href="ar.ly?search=ar">ar</a>