File Coverage

blib/lib/CSS/Compressor.pm

Criterion	Covered	Total	%
statement	73	73	100.0
branch	4	4	100.0
condition	19	26	73.0
subroutine	5	5	100.0
pod	1	1	100.0
total	102	109	93.5

package CSS::Compressor;

use strict;
use warnings;

use Exporter qw( import );

our @EXPORT_OK = qw( css_compress );

our $VERSION = '0.03';

our $MARKER;

# take package name, replace double colons with underscore and use that as
# marker for search and replace operations
BEGIN {
    $MARKER = uc __PACKAGE__;
    $MARKER =~ tr!:!_!s;
}

# build optimized regular expression variables ( foo -> [Ff][Oo][Oo] )
my (
    $RE_BACKGROUND_POSITION,
    $RE_TRANSFORM_ORIGIN_MOZ,
    $RE_TRANSFORM_ORIGIN_MS,
    $RE_TRANSFORM_ORIGIN_O,
    $RE_TRANSFORM_ORIGIN_WEBKIT,
    $RE_TRANSFORM_ORIGIN,
    $RE_BORDER,
    $RE_BORDER_TOP,
    $RE_BORDER_RIGHT,
    $RE_BORDER_BOTTOM,
    $RE_BORDER_LEFT,
    $RE_OUTLINE,
    $RE_BACKGROUND,
    $RE_ALPHA_FILTER,
) = map +(
    join '' => map m![a-zA-Z]!
       ? '['.ucfirst($_).lc($_).']'
       : '\\'.$_,
       split m//
) => qw[
    background-position
       moz-transform-origin
        ms-transform-origin
         o-transform-origin
    webkit-transform-origin
           transform-origin
    border
    border-top
    border-right
    border-bottom
    border-right
    outline
    background
    progid:DXImageTransform.Microsoft.Alpha(Opacity=
];

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
#  compress
#
#  IN: 1 uncompressed CSS
# OUT: 1 compressed CSS

sub css_compress {
    my ( $css ) = @_;
    my @comments,
    my @tokens;

    # collect all comment blocks...
    $css =~ s! /\* (.*?) \*/
             ! '/*___'.$MARKER.'_PRESERVE_CANDIDATE_COMMENT_'.
               ( -1 + push @comments => $1 ).'___*/'
             !sogex;

    # preserve urls to prevent breaking inline SVG for example
    $css =~ s! ( url \( (?: [^()] | (?1) )* \) ) !
        '___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => $1).'___'
        !gxe;

    # preserve strings so their content doesn't get accidentally minified
    $css =~ s! " ( [^"\\]*(?:\\.[^"\\]*)* ) " !
        $_ = $1,

        # maybe the string contains a comment-like substring?
        # one, maybe more? put'em back then
        s/___${MARKER}_PRESERVE_CANDIDATE_COMMENT_([0-9]+)___/$comments[$1]/go,

        # minify alpha opacity in filter strings
        s/$RE_ALPHA_FILTER/alpha(opacity=/go,

        '"___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => $_).'___"'
       !sgxe;
    $css =~ s! ' ( [^'\\]*(?:\\.[^'\\]*)* ) ' !
        $_ = $1,

        s/___${MARKER}_PRESERVE_CANDIDATE_COMMENT_([0-9]+)___/$comments[$1]/go,

        s/$RE_ALPHA_FILTER/alpha(opacity=/go,

        '\'___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => $_).'___\''
       !sgxe;

    # strings are safe, now wrestle the comments

    # ! in the first position of the comment means preserve
    # so push to the preserved tokens while stripping the !
    0 == index $_->[1] => '!'
      and -1 == index $_->[1] => '! @noflip'
      and
        $css =~ s!___${MARKER}_PRESERVE_CANDIDATE_COMMENT_$_->[0]___!
                 '___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => $_->[1]).'___'!e

    # keep empty comments after child selectors (IE7 hack)
    # e.g. html >/**/ body
    or 0 == length $_->[1]
      and
        $css =~ s!>/\*___${MARKER}_PRESERVE_CANDIDATE_COMMENT_$_->[0]___!
                 '>/*___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => '').'___'!e

    # \ in the last position looks like hack for Mac/IE5
    # shorten that to /*\*/ and the next one to /**/
    or '\\' eq substr $_->[1] => -1
      and
        $css =~ s!___${MARKER}_PRESERVE_CANDIDATE_COMMENT_$_->[0]___!
                 '___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => '\\').'___'!e &&
            # attention: inline modification
            ++$_->[0] &&
        $css =~ s!___${MARKER}_PRESERVE_CANDIDATE_COMMENT_$_->[0]___!
                 '___'.$MARKER.'_PRESERVED_TOKEN_'.(-1+push @tokens => '').'___'!e

        for map +[ $_, $comments[$_] ], 0..$#comments;

    # in all other cases kill the comment
    $css =~ s!/\*___${MARKER}_PRESERVE_CANDIDATE_COMMENT_([0-9]+)___\*/!!g;

    # Normalize all whitespace strings to single spaces. Easier to work with that way.
    $css =~ s!\s+! !g;


    # From here on all white space is just space - no more multi line matches!


    # Remove the spaces before the things that should not have spaces before them.
    # But, be careful not to turn "p :link {...}" into "p:link{...}"
    # Swap out any pseudo-class colons with the token, and then swap back.
    $css =~ s! ( \} [^{:]+ (?:: [^{:]+)+ \{ ) !
              $_ = $1,
              s/:/___${MARKER}_PSEUDOCLASSCOLON___/go,
              s/\\([\\\$])/\\$1/g,
              $_
             !gxe;
    $css =~ s! ( ^  [^{:]+ (?:: [^{:]+)+ \{ ) !
              $_ = $1,
              s/:/___${MARKER}_PSEUDOCLASSCOLON___/go,
              s/\\([\\\$])/\\$1/g,
              $_
             !xe;

    # Similarly, don't strip spaces around addition within calc(10px + 10px) -
    # swap out any calc()-related plus symbol to a token, and then swap back.
    # Recursive regular expression is needed to match nested brackets, for
    # example: `calc(10px + var(--foo))`.
    $css =~ s!calc(\((?:[^()]|(?1))*\))!
              $_ = $1,
              s/\+/___${MARKER}_CALCADDITIONSYMBOL___/go,
              "calc$_"
             !gxe;

    # Remove spaces before the things that should not have spaces before them.
    $css =~ s/ +([!{};:>+()\],])/$1/g;

    # bring back the colon
    $css =~ s!___${MARKER}_PSEUDOCLASSCOLON___!:!go;

    # retain space for special IE6 cases
    $css =~ s!:first\-(line|letter)([{,])!:first-$1 $2!g;

    # no space after the end of a preserved comment
    $css =~ s!\*/ !*/!g;

    # If there is a @charset, then only allow one, and push to the top of the file.
    $css =~ s!^(.*)(\@charset "[^"]*";)!$2$1!g;
    $css =~ s!^( *\@charset [^;]+; *)+!$1!g;

    # Put the space back in some cases, to support stuff like
    # @media screen and (-webkit-min-device-pixel-ratio:0){
    # @supports((display: flex) or (display: -webkit-flex))
    $css =~ s! \b and \( !and (!gx;
    $css =~ s! \b or \( !or (!gx;

    # Remove the spaces after the things that should not have spaces after them.
    $css =~ s/([!{},;:>+(\[]) +/$1/g;

    # Swap back the plus sign from calc() addition.
    $css =~ s!___${MARKER}_CALCADDITIONSYMBOL___!+!go;

    # Replace 0.6 to .6, but only when preceded by :
    $css =~ s!:0+\.([0-9]+)!:.$1!g;

    # remove unnecessary semicolons
    $css =~ s!;+\}!}!g;

    # Replace 0(px,em,%) with 0
    $css =~ s!([ :]0)(?:px|em|%|in|cm|mm|pc|pt|ex)!$1!g;

    # Replace 0 0 0 0; with 0.
    $css =~ s!:0(?: 0){0,3}(;|})!:0$1!g;

    # Replace background-position:0; with background-position:0 0;
    # same for transform-origin
    $css =~ s! $RE_BACKGROUND_POSITION     :0 ( [;}] ) !background-position:0 0$1!gox;
    $css =~ s! $RE_TRANSFORM_ORIGIN_MOZ    :0 ( [;}] ) !moz-transform-origin:0 0$1!gox;
    $css =~ s! $RE_TRANSFORM_ORIGIN_MS     :0 ( [;}] ) !ms-transform-origin:0 0$1!gox;
    $css =~ s! $RE_TRANSFORM_ORIGIN_O      :0 ( [;}] ) !o-transform-origin:0 0$1!gox;
    $css =~ s! $RE_TRANSFORM_ORIGIN_WEBKIT :0 ( [;}] ) !webkit-transform-origin:0 0$1!gox;
    $css =~ s! $RE_TRANSFORM_ORIGIN        :0 ( [;}] ) !transform-origin:0 0$1!gox;

    # Replace 0.6 to .6, but only when preceded by : or a white-space
    $css =~ s! 0+\.([0-9]+)! .$1!g;

    # Shorten colors from rgb(51,102,153) to #336699
    # This makes it more likely that it'll get further compressed in the next step.
    $css =~ s!rgb *\( *([0-9, ]+) *\)!
               sprintf('#%02x%02x%02x',
                 split(m/ *, */, $1, 3) )
             !ge;

    # Shorten colors from #AABBCC to #ABC. Note that we want to make sure
    # the color is not preceded by either ", " or =. Indeed, the property
    #     filter: chroma(color="#FFFFFF");
    # would become
    #     filter: chroma(color="#FFF");
    # which makes the filter break in IE.
    # We also want to make sure we're only compressing #AABBCC patterns inside
    # { }, not id selectors ( #FAABAC {} ).
    # Further we want to avoid compressing invalid values (e.g. #AABBCCD to #ABCD).
    $css =~ s!
        (=[ ]*?["']?)?
        \#
        ([0-9a-fA-F]) # a
        ([0-9a-fA-F]) # a
        ([0-9a-fA-F]) # b
        ([0-9a-fA-F]) # b
        ([0-9a-fA-F]) # c
        ([0-9a-fA-F]) # c
        \b
        ([^{.])
      !
        ( $1 || '' ) ne ''
          # keep as compression will break filters
          ? $1.'#'.$2.$3.$4.$5.$6.$7.$8
          # not a filter, safe to compress
          : '#'.lc(
                lc $2.$4.$6 eq lc $3.$5.$7
                 ? $2.$4.$6
                 : $2.$3.$4.$5.$6.$7
             ).$8
      !gex;

    # border: none -> border:0
    $css =~ s! $RE_BORDER        :none ( [;}] ) !border:0$1!gox;
    $css =~ s! $RE_BORDER_TOP    :none ( [;}] ) !border-top:0$1!gox;
    $css =~ s! $RE_BORDER_RIGHT  :none ( [;}] ) !border-right:0$1!gox;
    $css =~ s! $RE_BORDER_BOTTOM :none ( [;}] ) !border-bottom:0$1!gox;
    $css =~ s! $RE_BORDER_LEFT   :none ( [;}] ) !border-left:0$1!gox;
    $css =~ s! $RE_OUTLINE       :none ( [;}] ) !outline:0$1!gox;
    $css =~ s! $RE_BACKGROUND    :none ( [;}] ) !background:0$1!gox;

    # shorter opacity IE filter
    $css =~ s!$RE_ALPHA_FILTER!alpha(opacity=!go;

    # Remove empty rules.
    $css =~ s![^{}/;]+\{\}!!g;

    # Replace multiple semi-colons in a row by a single one
    # See SF bug #1980989
    $css =~ s!;;+!;!g;

    # restore preserved comments and strings
    $css =~ s!___${MARKER}_PRESERVED_TOKEN_([0-9]+)___!$tokens[$1]!go;

    # Trim the final string (for any leading or trailing white spaces)
    $css =~ s!\A +!!;
    $css =~ s! +\z!!;

    $css;
}

1;

__END__