PHP Regex to remove specific CSS Comment

问题:

I want to write the regular expression in php matching condition below:

   /* 
    Remove this comment line 1
    Remove this comment line 2
   */
   .class1
   {
      background:#CCC url(images/bg.png);
   }

   .class2
   {
      color: #FFF;
      background:#666 url(images/bg.png); /* DON'T remove this comment */
   }

   /* Remove this comment */
   .class3
   {
      margin:2px;
      color:#999;
      background:#FFF; /* DON'T Remove this comment */
   }

    ...etc
    ...etc

Please any one give me a regular expression in php. Thanks.

回答1:

If the rule is that you want to remove all comments where there is no other code on the line then something like this should work:

/^(\s*\/\*.*?\*\/\s*)$/m

The 'm' option makes ^ and $ match the beginning and end of a line. Do you expect the comments to run for more than one line?

EDIT:

I'm pretty sure this fits the bill:

/(^|\n)\s*\/\*.*?\*\/\s*/s

Do you understand what it's doing?

回答2:

Not working for multiline comments like

/*
 * Lorem ipsum
 */

This one do the job

$regex = "!/\*[^*]*\*+([^/][^*]*\*+)*/!";
$newstr = preg_replace($regex,"",$str);
echo $newstr;

http://codepad.org/xRb2Gdhy

Found here : http://www.catswhocode.com/blog/3-ways-to-compress-css-files-using-php

回答3:

Codepad: http://codepad.org/aMvQuJSZ

Support multiline:

/* Remove this comment 
multi-lane style 1*/

/* Remove this comment 
multi-lane style 2
*/

/* Remove this comment */

Regex Explanation:

^            Start of line
\s*          only contains whitespace
\/\*         continue with /*
[^(\*\/)]*   unlimited number of character except */ includes newline
\*\/         continue with */
m            pattern modifier (makes ^ start of line, $ end of line

Example php code:

$regex = "/^\s*\/\*[^(\*\/)]*\*\//m";
$newstr = preg_replace($regex,"",$str);
echo $newstr;