preg_replace out CSS comments? - php

Question

I'm writing a quick preg_replace to strip comments from CSS. CSS comments usually have this syntax:
/* Development Classes*/
/* Un-comment me for easy testing
(will make it simpler to see errors) */
So I'm trying to kill everything between /* and */, like so:
$pattern = "#/\*[^(\*/)]*\*/#";
$replace = "";
$v = preg_replace($pattern, $replace, $v);
No dice! It seems to be choking on the forward slashes, because I can get it to remove the text of comments if I take the /s out of the pattern. I tried some simpler patterns to see if I could just lose the slashes, but they return the original string unchanged:
$pattern = "#/#";
$pattern = "/\//";
Any ideas on why I can't seem to match those slashes? Thanks!

Answer 1

Here's a solution:
$regex = array(
"`^([\t\s]+)`ism"=>'',
"`^\/\*(.+?)\*\/`ism"=>"",
"`([\n\A;]+)\/\*(.+?)\*\/`ism"=>"$1",
"`([\n\A;\s]+)//(.+?)[\n\r]`ism"=>"$1\n",
"`(^[\r\n]*|[\r\n]+)[\s\t]*[\r\n]+`ism"=>"\n"
);
$buffer = preg_replace(array_keys($regex),$regex,$buffer);
Taken from the Script/Stylesheet Pre-Processor in Samstyle PHP Framework
See: http://code.google.com/p/samstyle-php-framework/source/browse/trunk/sp.php
csstest.php:
<?php
$buffer = file_get_contents('test.css');
$regex = array(
"`^([\t\s]+)`ism"=>'',
"`^\/\*(.+?)\*\/`ism"=>"",
"`([\n\A;]+)\/\*(.+?)\*\/`ism"=>"$1",
"`([\n\A;\s]+)//(.+?)[\n\r]`ism"=>"$1\n",
"`(^[\r\n]*|[\r\n]+)[\s\t]*[\r\n]+`ism"=>"\n"
);
$buffer = preg_replace(array_keys($regex),$regex,$buffer);
echo $buffer;
?>
test.css:
/* testing to remove this */
.test{}
Output of csstest.php:
.test{}

Answer 2

I don't believe you can use grouping within a negated character class like you have there. What you're going to want to use is called Assertions, of which there are two types. "look-ahead" and "look-behind".
The pattern you're looking for in English is basically, "forward slash, literal wildcard, anything that isn't followed by a forward slash or anything other than a literal wildcard that is followed by a forward slash or a forward slash that isn't preceded by a literal wildcard zero or more times, literal wild card, forward slash"
<?php
$str = '/* one */ onemore
/*
* a
* b
**/
stuff // single line
/**/';
preg_match_all('#/\*(?:.(?!/)|[^\*](?=/)|(?<!\*)/)*\*/#s', $str, $matches);
print_r($matches);
?>

Answer 3

I had the same issue.
To solve it, I first simplified the code by replacing "/ASTERIX" and "ASTERIX/" with different identifiers and then used those as the start and end markers.
$code = str_replace("/*","_COMSTART",$code);
$code = str_replace("*/","COMEND_",$code);
$code = preg_replace("/_COMSTART.*?COMEND_/s","",$code);
The /s flag tells the search to go onto new lines

Answer 4

There's a number of suggestions out there, but this one seems to work for me:
$v=preg_replace('!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $v);
so
"/* abc */.test { color:white; } /* XYZ */.test2 { padding:1px; /* DEF */} /* QWERTY */"
gives
.test { color:white; } .test2 { padding:1px; }
see https://onlinephp.io/c/2ae1c for working test

Answer 5

Just for fun(and small project of course) I made a non-regexp version of a such code (I hope it's faster):
function removeCommentFromCss( $textContent )
{
$clearText = "";
$charsInCss = strlen( $textContent );
$searchForStart = true;
for( $index = 0; $index < $charsInCss; $index++ )
{
if ( $searchForStart )
{
if ( $textContent[ $index ] == "/" && (( $index + 1 ) < $charsInCss ) && $textContent[ $index + 1 ] == "*" )
{
$searchForStart = false;
continue;
}
else
{
$clearText .= $textContent[ $index ];
}
}
else
{
if ( $textContent[ $index ] == "*" && (( $index + 1 ) < $charsInCss ) && $textContent[ $index + 1 ] == "/" )
{
$searchForStart = true;
$index++;
continue;
}
}
}
return $clearText;
}