Function which searches for a word in a text and highlights all the words which contain it

Question

This function searches for words (from the $words array) inside a text and highlights them.

function highlightWords(Array $words, $text){ // Loop through array of words
    foreach($words as $word){ // Highlight word inside original text
        $text = str_replace($word, '<span class="highlighted">' . $word . '</span>', $text);
    }         
    return $text; // Return modified text
}

Here is the problem:

Lets say the $words = array("car", "drive");

Is there a way for the function to highlight not only the word car, but also words which contain the letters "car" like: cars, carmania, etc.

Thank you!

Answer 1

What you want is a regular expression, preg_replace or peg_replace_callback more in particular (callback in your case would be recommended)

<?php
$searchString = "The car is driving in the carpark, he's not holding to the right lane.\n";

// define your word list
$toHighlight = array("car","lane");

Because you need a regular expression to search your words and you might want or need variation or changes over time, it's bad practice to hard code it into your search words. Hence it's best to walk over the array with array_map and transform the searchword into the proper regular expression (here just enclosing it with / and adding the "accept everything until punctuation" expression)

$searchFor = array_map('addRegEx',$toHighlight);

// add the regEx to each word, this way you can adapt it without having to correct it everywhere
function addRegEx($word){
    return "/" . $word . '[^ ,\,,.,?,\.]*/';
}

Next you wish to replace the word you found with your highlighted version, which means you need a dynamic change: use preg_replace_callback instead of regular preg_replace so that it calls a function for every match it find and uses it to generate the proper result. Here we enclose the found word in its span tags

function highlight($word){
    return "<span class='highlight'>$word[0]</span>";
}

$result = preg_replace_callback($searchFor,'highlight',$searchString);

print $result;

yields

The <span class='highlight'>car</span> is driving in the <span class='highlight'>carpark</span>, he's not holding to the right <span class='highlight'>lane</span>.

So just paste these code fragments after the other to get the working code, obviously. ;)

edit: the complete code below was altered a bit = placed in routines for easy use by original requester. + case insensitivity

complete code:

<?php

$searchString = "The car is driving in the carpark, he's not holding to the right lane.\n";
$toHighlight = array("car","lane");

$result = customHighlights($searchString,$toHighlight);

print $result;

// add the regEx to each word, this way you can adapt it without having to correct it everywhere

function addRegEx($word){
    return "/" . $word . '[^ ,\,,.,?,\.]*/i';
}

function highlight($word){
    return "<span class='highlight'>$word[0]</span>";
}

function customHighlights($searchString,$toHighlight){

// define your word list
$searchFor = array_map('addRegEx',$toHighlight);
$result = preg_replace_callback($searchFor,'highlight',$searchString);
return $result;

}

Answer 2

I haven't tested it, but I think this should do it:-

$text = preg_replace('/\W((^\W)?$word(^\W)?)\W/', '<span class="highlighted">' . $1 . '</span>', $text);

This looks for the string inside a complete bounded word and then puts the span around the whole lot using preg_replace and regular expressions.

Answer 3

function replace($format, $string, array $words)
{
    foreach ($words as $word) {
        $string = \preg_replace(
            sprintf('#\b(?<string>[^\s]*%s[^\s]*)\b#i', \preg_quote($word, '#')),
            \sprintf($format, '$1'), $string);
    }
    return $string;
}


// courtesy of http://slipsum.com/#.T8PmfdVuBcE
$string = "Now that we know who you are, I know who I am. I'm not a mistake! It
all makes sense! In a comic, you know how you can tell who the arch-villain's
going to be? He's the exact opposite of the hero. And most times they're friends,
like you and me! I should've known way back when... You know why, David? Because
of the kids. They called me Mr Glass.";

echo \replace('<span class="red">%s</span>', $string, [
    'mistake',
    'villain',
    'when',
    'Mr Glass',
]);

Sine it's using an sprintf format for the surrounding string, you can change your replacement accordingly.

_{Excuse the 5.4 syntax}