Replace several words in string using associative array keeping original case intact

Question

I want to match an array against a text string where words matching with the array keys will be replaced by a span tag with a title with the matching array value.

I can

Answer 1

You can achieve it with some common PHP functions.

1. Create an array of patterns from your keys to search in a case-insensitive manner with preg_replace_callback.

2. Pass the $glossary to the anonymous function in preg_replace_callback and get the value (the <span> title) by the lowercased current match value, and once found, replace the lowercase wordX with the match.

This is PHP code:

$pttrns = array_map(function ($val) {return "/" . preg_quote($val) . "/i"; },
                  array_keys($glossary));                                    // Step 1
$res = preg_replace_callback($pttrns, function ($m) use($glossary){          // Step 2
    return str_replace(strtolower($m[0]), $m[0],              
                                     $glossary[strtolower($m[0])]);         // Step 3
}, $text);

Answer 2

You can run this replace in loop:

$txt = 'Hi! How are you doing? Have some stars: * * *!';
$glossary = array(
    'Hi!'   => 'title 1',
    'stars' => 'title 2',
    '*'     => 'title 3'
);
$result = $txt;
foreach ($glossary as $keyword => $title) {
    $pattern = '#(?<=^|\W)('.preg_quote($keyword).')(?=$|\W)#i';
    $result  = preg_replace($pattern, "<span title='{$title}'>$1</span>", $result);
}
echo $result;