PHP Regex Key phrase matching

Question

I have a text field where the user will enter comma separated keywords or key phrases, and the server will then use these values to check multiple bodies of text for matches.

So basically what I need is to match an exact phrase, case insensitive, with possible spaces in a body of text.

I can match keywords easily, by generating the following regex:

Example keywords: peanut, butter, jelly

Regex generated: /peanut|butter|jelly/i

However having spaces does not work. Even if I replace the spaces in the given values with \s

Example: peanut butter, jelly sandwich, delicious

Regex: /peanut\sbutter|jelly\ssandwich|delicious/i

What would be a correct regex to match the phrases exactly ? Case insensitive and using PHP's preg_match ?

Thanks.

EDIT

This is what I am doing:

$keywordsArray = array_map( 'trim', explode( ',', $keywords ) );
$keywordsArrayEscaped = array_map( 'preg_quote', $keywordsArray );
$keywordsRegex = '/' . implode( '|', $keywordsArrayEscaped ) . '/i';

The above generates the expressions as described above ( Without the replacement of spaces to \s, since it didn't work. )

Following that I simple do preg_match( $keywordsRegex, $text );

I don't see thee issue. Spaces work for in preg_match for me. Provide some code. — John
– John, Commented Jul 23, 2013 at 16:26
where are the target text you're trying to check come from? are they encoded like  ? — Paul Chen
– Paul Chen, Commented Jul 23, 2013 at 16:28
show us your code. impossible to help unless you do, because we don't know what's actually going on in your specific situation. preg_match can handle both spaces and \s just fine, so that's not the problem. — user428517
– user428517, Commented Jul 23, 2013 at 16:30
Yea, but I am walking the array and trimming the values. So it's pretty much the same thing. — Zyyk Savvins
– Zyyk Savvins, Commented Jul 23, 2013 at 16:30

Adi Inbar · Accepted Answer · 2013-07-23 16:31:33Z

3

I don't see why it wouldn't work with spaces or \s. It should. But to answer the question you asked in general terms, the way to match exact phrases in a regex is to surround them with \Q and \E:

/\Q<phrase 1>\E|\Q<phrase 2>\E|\Q<phrase 3>\E/

That's normally used for text that contains escapes or regex metacharacters. You really shouldn't need that for spaces.

answered Jul 23, 2013 at 16:31

Adi Inbar

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Comments

John · Accepted Answer · 2013-07-23 16:40:19Z

0

The only issue I could really find with your code is that you aren't filling in the third field for the results;

preg_match($keywordsRegex, $text, $results);

var_dump($results);

answered Jul 23, 2013 at 16:40

John

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1 Comment

Zyyk Savvins Over a year ago

Because I'm only concerned with whether or not it matched.

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