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https://github.com/bleargh45/css-minifier-xs

XS based CSS minifier
https://github.com/bleargh45/css-minifier-xs

css-minifier minification minifier minify-css perl xs

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XS based CSS minifier

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README 

        
# NAME



CSS::Minifier::XS - XS based CSS minifier



# SYNOPSIS



```perl

use CSS::Minifier::XS qw(minify);

my $css      = '...';

my $minified = minify($css);

```



# DESCRIPTION



`CSS::Minifier::XS` is a CSS "minifier"; its designed to remove unnecessary

whitespace and comments from CSS files, while also **not** breaking the CSS.



`CSS::Minifier::XS` is similar in function to `CSS::Minifier`, but is

substantially faster as its written in XS and not just pure Perl.



# METHODS



- minify($css)



    Minifies the given `$css`, returning the minified CSS back to the caller.



# HOW IT WORKS



`CSS::Minifier::XS` minifies the CSS by removing unnecessary whitespace from

CSS documents.  Comment blocks are also removed, _except_ when (a) they

contain the word "copyright" in them, or (b) they're needed to implement the

"Mac/IE Comment Hack".



Internally, the minification is done by taking multiple passes through the CSS

document:



## Pass 1: Tokenize



First, we go through and parse the CSS document into a series of tokens

internally.  The tokenizing process **does not** check to make sure that you've

got syntactically valid CSS, it just breaks up the text into a stream of tokens

suitable for processing by the subsequent stages.



## Pass 2: Collapse



We then march through the token list and collapse certain tokens down to their

smallest possible representation.  _If_ they're still included in the final

results we only want to include them at their shortest.



- Whitespace



    Runs of multiple whitespace characters are reduced down to a single whitespace

    character.  If the whitespace contains any "end of line" (EOL) characters, then

    the end result is the _first_ EOL character encountered.  Otherwise, the

    result is the first whitespace character in the run.



- Comments



    Comments implementing the "Mac/IE Comment Hack" are collapsed down to the

    smallest possible comment that would still implement the hack ("/\*\\\*/" to start

    the hack, and "/\*\*/" to end it).



- Zero Units



    Zero Units (e.g. `0px`) are reduced down to just "0", as the CSS specification

    indicates that the unit is not required when its a zero value.



## Pass 3: Pruning



We then go back through the token list and prune and remove unnecessary

tokens.



- Whitespace



    Wherever possible, whitespace is removed; before+after comment blocks, and

    before+after various symbols/sigils.



- Comments



    Comments that either (a) are needed to implement the "Mac/IE Comment Hack", or

    that (b) contain the word "copyright" in them are preserved.  **All** other

    comments are removed.



- Symbols/Sigils



    Semi-colons that are immediately followed by a closing brace (e.g. ";}") are

    removed; semi-colons are needed to separate multiple declarations, but aren't

    required at the end of a group.



- Everything else



    We keep everything else; identifiers, quoted literal strings, symbols/sigils,

    etc.



## Pass 4: Re-assembly



Lastly, we go back through the token list and re-assemble it all back into a

single CSS string, which is then returned back to the caller.



# AUTHOR



Graham TerMarsch ([email protected])



# COPYRIGHT



Copyright (C) 2007-, Graham TerMarsch.  All Rights Reserved.



This is free software; you can redistribute it and/or modify it under the same

license as Perl itself.



# SEE ALSO



`CSS::Minifier`.