Question

I’m trying to wrap words and words sequence from a given list with preg_replace. It almost works, but there are some use cases it doesn’t and I can’t figure it how.

For instance I do this:

    // sort by descending length
    usort($this->_keywords, function($a,$b){return(strlen($a)<strlen($b));});

    // wrapper is -%string%-
    foreach ($this->_keywords as $keyword) {
        $value = preg_replace('/((?!-)' . $keyword . '(?!-))/i', str_replace('%string%', '\1', $this->_wrapper), $value);
    }

From this keyword list:

• lorem
• ipsum
• sit amet
• null
• sed
• sed enim

I’d like to result in:

-Lorem- -ipsum- dolor -sit amet-,
consectetur adipiscing elit. Phasellus
rhoncus venenatis orci sed porta. Sed
non dolor eros. Suspendisse a massa
-sit amet- nulla egestas facilisis. Cras
fringilla, leo ac ullamcorper semper,
urna eros pretium lectus, nec rhoncus
ligula risus eu velit. Nulla eu
dapibus magna. Sed vehicula tristique
lacinia. Maecenas tincidunt metus at
urna consequat nec congue libero
iaculis. Nulla facilisi. Phasellus -sed-
sem ut risus mattis accumsan eu -sed
enim-. Pellentesque habitant morbi
tristique senectus et netus et
malesuada fames ac turpis egestas.
Suspendisse id est velit, eu cursus
quam. Vivamus lacinia euismod pretium.

Any ideas?

Answer 1

I finally resolved my problems by using the \b metacharacters which correspond to a word boundary.

public function filter($value)
{
    usort($this->_keywords, function($a,$b){return(strlen($a)<strlen($b));});

    foreach ($this->_keywords as $keyword) {
        $value = preg_replace(
            '/((?<!-)('.$keyword.'\b)(?!\-))/i',
            str_replace('%string%', '\2', $this->_wrapper) . '\3',
            $value
        );
    }

    return $value;
}