README
1NAME
2
3 CSS::Minifier::XS - XS based CSS minifier
4
5SYNOPSIS
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7 use CSS::Minifier::XS qw(minify);
8 my $css = '...';
9 my $minified = minify($css);
10
11DESCRIPTION
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13 CSS::Minifier::XS is a CSS "minifier"; its designed to remove
14 unnecessary whitespace and comments from CSS files, while also not
15 breaking the CSS.
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17 CSS::Minifier::XS is similar in function to CSS::Minifier, but is
18 substantially faster as its written in XS and not just pure Perl.
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20METHODS
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22 minify($css)
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24 Minifies the given $css, returning the minified CSS back to the
25 caller.
26
27HOW IT WORKS
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29 CSS::Minifier::XS minifies the CSS by removing unnecessary whitespace
30 from CSS documents. Comment blocks are also removed, except when (a)
31 they contain the word "copyright" in them, or (b) they're needed to
32 implement the "Mac/IE Comment Hack".
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34 Internally, the minification is done by taking multiple passes through
35 the CSS document:
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37 Pass 1: Tokenize
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39 First, we go through and parse the CSS document into a series of tokens
40 internally. The tokenizing process does not check to make sure that
41 you've got syntactically valid CSS, it just breaks up the text into a
42 stream of tokens suitable for processing by the subsequent stages.
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44 Pass 2: Collapse
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46 We then march through the token list and collapse certain tokens down
47 to their smallest possible representation. If they're still included in
48 the final results we only want to include them at their shortest.
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50 Whitespace
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52 Runs of multiple whitespace characters are reduced down to a single
53 whitespace character. If the whitespace contains any "end of line"
54 (EOL) characters, then the end result is the first EOL character
55 encountered. Otherwise, the result is the first whitespace character
56 in the run.
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58 Comments
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60 Comments implementing the "Mac/IE Comment Hack" are collapsed down to
61 the smallest possible comment that would still implement the hack
62 ("/*\*/" to start the hack, and "/**/" to end it).
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64 Zero Units
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66 Zero Units (e.g. 0px) are reduced down to just "0", as the CSS
67 specification indicates that the unit is not required when its a zero
68 value.
69
70 Pass 3: Pruning
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72 We then go back through the token list and prune and remove unnecessary
73 tokens.
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75 Whitespace
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77 Wherever possible, whitespace is removed; before+after comment
78 blocks, and before+after various symbols/sigils.
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80 Comments
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82 Comments that either (a) are needed to implement the "Mac/IE Comment
83 Hack", or that (b) contain the word "copyright" in them are
84 preserved. All other comments are removed.
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86 Symbols/Sigils
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88 Semi-colons that are immediately followed by a closing brace (e.g.
89 ";}") are removed; semi-colons are needed to separate multiple
90 declarations, but aren't required at the end of a group.
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92 Everything else
93
94 We keep everything else; identifiers, quoted literal strings,
95 symbols/sigils, etc.
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97 Pass 4: Re-assembly
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99 Lastly, we go back through the token list and re-assemble it all back
100 into a single CSS string, which is then returned back to the caller.
101
102AUTHOR
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104 Graham TerMarsch (cpan@howlingfrog.com)
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106COPYRIGHT
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108 Copyright (C) 2007-, Graham TerMarsch. All Rights Reserved.
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110 This is free software; you can redistribute it and/or modify it under
111 the same license as Perl itself.
112
113SEE ALSO
114
115 CSS::Minifier.
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