Module: CssCompressor

Defined in:

lib/cssminify/cssmin.rb

Overview

cssmin.rb - 1.0.1 Author: Matthias Siegel - github.com/matthiassiegel/cssmin This is a Ruby port of the CSS minification tool distributed with YUICompressor, based on the original Java code and the Javascript port by Stoyan Stefanov. Permission is hereby granted to use the Ruby version under the same conditions as YUICompressor (original YUICompressor note below).

YUI Compressor developer.yahoo.com/yui/compressor/ Author: Julien Lecomte - www.julienlecomte.net/ Author: Isaac Schlueter - foohack.com/ Author: Stoyan Stefanov - phpied.com/ Copyright © 2011 Yahoo! Inc. All rights reserved. The copyrights embodied in the content of this file are licensed by Yahoo! Inc. under the BSD (revised) open source license.

Class Method Summary

• .compress(css, linebreakpos = 5000) ⇒ Object

Class Method Details

.compress(css, linebreakpos = 5000) ⇒ Object

# File 'lib/cssminify/cssmin.rb', line 23

def self.compress(css, linebreakpos = 5000)
  
  #
  # Support for various input types
  #
  if css.respond_to?(:read)
    css = css.read
  elsif css.respond_to?(:path)
    css = File.read(css.path)
  end
  
  @@preservedTokens = []
  comments = []
  startIndex = 0
  
  #
  # Extract data urls
  #
  css = extractDataUrls(css)
  
  #
  # Collect all comment blocks...
  #
  while (startIndex = css.index(/\/\*/, startIndex)) != nil
    endIndex = css.index(/\*\//, startIndex + 2)
    endIndex = css.length if endIndex.nil?
    
    comments << css[(startIndex + 2)...endIndex]
    
    css = css[0...(startIndex + 2)] + '___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_' + (comments.length - 1).to_s + '___' + css[endIndex..-1]
    startIndex += 2
  end
  
  #
  # Preserve strings so their content doesn't get accidentally minified
  #
  css = css.gsub(/("([^\\"]|\\.|\\)*")|('([^\\']|\\.|\\)*')/) { |match| 
    quote = match[0, 1]
    match = match[1...-1]
    
    #
    # Maybe the string contains a comment-like substring?
    # One, maybe more? put'em back then
    #
    unless match.index('___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_').nil?
      comments.each_index { |i| match = match.gsub(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{i}___/, comments[i]) }
    end
    
    #
    # Minify alpha opacity in filter strings
    #
    match = match.gsub(/progid:DXImageTransform\.Microsoft\.Alpha\(Opacity=/i, 'alpha(opacity=')
    
    @@preservedTokens << match
    
    quote + "___YUICSSMIN_PRESERVED_TOKEN_" + (@@preservedTokens.length - 1).to_s + "___" + quote
  }
  
  #
  # Strings are safe, now wrestle the comments
  #
  for i in 0...comments.length
    token = comments[i]
    placeholder = /___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{i}___/
    
    #
    # ! in the first position of the comment means preserve
    # so push to the preserved tokens keeping the !
    #
    if token[0] === '!'
      @@preservedTokens << token
      css = css.gsub(placeholder, "___YUICSSMIN_PRESERVED_TOKEN_" + (@@preservedTokens.length - 1).to_s + "___")
      next
    end
    
    #
    # \ in the last position looks like hack for Mac/IE5
    # shorten that to /*\*/ and the next one to /**/
    #
    if token[(token.length - 1)..-1] === '\\'
      @@preservedTokens << '\\'
      css = css.gsub(placeholder, "___YUICSSMIN_PRESERVED_TOKEN_" + (@@preservedTokens.length - 1).to_s + "___")
      
      i += 1  # Attn: advancing the loop
      
      @@preservedTokens << ''
      css = css.gsub(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{i}___/, "___YUICSSMIN_PRESERVED_TOKEN_" + (@@preservedTokens.length - 1).to_s + "___")
      next
    end
    
    #
    # Keep empty comments after child selectors (IE7 hack)
    # E.g. html >/**/ body
    #
    if token.length == 0
      startIndex = css.index(placeholder)
      
      if startIndex and startIndex > 2
        if css[startIndex - 3] === '>'
          @@preservedTokens << ''
          css = css.gsub(placeholder, "___YUICSSMIN_PRESERVED_TOKEN_" + (@@preservedTokens.length - 1).to_s + "___")
        end
      end
    end
    
    #
    # In all other cases kill the comment
    #
    css = css.gsub(/\/\*___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{i}___\*\//, '')
  end
  
  #
  # Shorten all whitespace strings to single spaces
  #
  css = css.gsub(/\s+/, ' ')
  
  #
  # 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 = css.gsub(/(^|\})(([^\{:])+:)+([^\{]*\{)/) { |m| m.gsub(/:/, '___YUICSSMIN_PSEUDOCLASSCOLON___') }
  css = css.gsub(/\s+([!{};:>+\(\)\],])/) { $1.to_s }
  css = css.gsub(/___YUICSSMIN_PSEUDOCLASSCOLON___/, ':')
  
  #
  # Retain space for special IE6 cases
  #
  css = css.gsub(/:first-(line|letter)(\{|,)/i) { ":first-#{$1.to_s.downcase} #{$2.to_s}" }
  
  #
  # No space after the end of a preserved comment
  #
  css = css.gsub(/\*\/\s+/, '*/')
  
  #
  # If there is a @charset, then only allow one, and push to the top of the file.
  #
  css = css.gsub(/^(.*)(@charset "[^"]*";)/i) { $2.to_s + $1.to_s }
  css = css.gsub(/^(\s*@charset [^;]+;\s*)+/i) { $1.to_s }
  
  #
  # Put the space back in some cases, to support stuff like
  # @media screen and (-webkit-min-device-pixel-ratio:0){
  #
  css = css.gsub(/\band\(/i, 'and (')
  
  #
  # Remove the spaces after the things that should not have spaces after them.
  #
  css = css.gsub(/([!{}:;>+\(\[,])\s+/) { $1.to_s }
  
  #
  # Remove unnecessary semicolons
  #
  css = css.gsub(/;+\}/, '}')
  
  #
  # Replace 0(px,em,%) with 0
  #
  css = css.gsub(/(^|[^0-9])(?:0?\.)?0(?:px|em|%|in|cm|mm|pc|pt|ex|deg|g?rad|m?s|k?hz)/i) { $1.to_s + '0' }
  
  #
  # Replace 0 0 0 0; with 0
  #
  css = css.gsub(/:0 0 0 0(;|\})/) { ':0' + $1.to_s }
  css = css.gsub(/:0 0 0(;|\})/) { ':0' + $1.to_s }
  css = css.gsub(/:0 0(;|\})/) { ':0' + $1.to_s }
  
  #
  # Replace background-position:0; with background-position:0 0;
  # Same for transform-origin
  #
  css = css.gsub(/(background-position|transform-origin|webkit-transform-origin|moz-transform-origin|o-transform-origin|ms-transform-origin):0(;|\})/i) { "#{$1.to_s.downcase}:0 0#{$2.to_s}" }
  
  #
  # Replace 0.6 to .6, but only when preceded by : or a white-space
  #
  css = css.gsub(/(:|\s)0+\.(\d+)/) { "#{$1.to_s}.#{$2.to_s}" }
  
  #
  # 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 = css.gsub(/rgb\s*\(\s*([0-9,\s]+)\s*\)(\d+%)?/i) {
    rgbcolors = $1.to_s.split(',')
    i = 0
    
    while i < rgbcolors.length
      rgbcolors[i] = rgbcolors[i].to_i.to_s(16)
      
      if rgbcolors[i].length === 1
        rgbcolors[i] = '0' + rgbcolors[i]
      end
      
      i += 1
    end
    
    unless $2.to_s.empty?
      rgbcolors << (' ' + $2.to_s)
    end
    
    '#' + rgbcolors.join('')
  }
  
  #
  # 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 {} )
  # We also want to avoid compressing invalid values (e.g. #AABBCCD to #ABCD)
  #
  rest = css
  new_css = ''
  
  while m = rest.match(/(\=\s*?["']?)?#([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])(:?\}|[^0-9a-f{][^{]*?\})/i) do
    #
    # Normal color value
    #
    if m[1].nil?
      #
      # Color value that can be shortened
      #
      if m[2].to_s.downcase == m[3].to_s.downcase && m[4].to_s.downcase == m[5].to_s.downcase && m[6].to_s.downcase == m[7].to_s.downcase
        color = '#' + m[2].to_s.downcase + m[4].to_s.downcase + m[6].to_s.downcase
        shift = 7
        
      #
      # Color value that can't be shortened
      #
      else
        color = '#' + m[2].to_s.downcase + m[3].to_s.downcase + m[4].to_s.downcase + m[5].to_s.downcase + m[6].to_s.downcase + m[7].to_s.downcase
        shift = 7
      end
      
    #
    # Filter property that needs to stay the way it is
    #
    else
      color = m[1].to_s + '#' + m[2].to_s + m[3].to_s + m[4].to_s + m[5].to_s + m[6].to_s + m[7].to_s
      shift = color.length
    end
    
    new_css += m.pre_match + color
    rest.slice!(rest.index(m.pre_match || 0), m.pre_match.length + shift)
  
  end
  css = new_css + rest
  
  #
  # border: none -> border:0
  #
  css = css.gsub(/(border|border-top|border-right|border-bottom|border-left|outline|background):none(;|\})/i) { "#{$1.to_s.downcase}:0#{$2.to_s}" }
  
  #
  # Shorter opacity IE filter
  #
  css = css.gsub(/progid:DXImageTransform\.Microsoft\.Alpha\(Opacity=/i, 'alpha(opacity=')
  
  #
  # Remove empty rules.
  #
  css = css.gsub(/[^\};\{\/]+\{\}/, '')
  
  #
  # Some source control tools don't like it when files containing lines longer
  # than, say 8000 characters, are checked in. The linebreak option is used in
  # that case to split long lines after a specific column.
  #
  if linebreakpos
    startIndex = 0
    i = 0
    while i < css.length
      i = i + 1
      if css[i - 1] === '}' && i - startIndex > linebreakpos
        css = css.slice(0, i) + "\n" + css.slice(i, css.length - i)
        startIndex = i
      end
    end
  end
  
  #
  # Replace multiple semi-colons in a row by a single one
  #
  css = css.gsub(/;;+/, ';')
  
  #
  # Restore preserved comments and strings
  #
  for i in 0...@@preservedTokens.length do
    css = css.gsub(/___YUICSSMIN_PRESERVED_TOKEN_#{i}___/) { @@preservedTokens[i] }
  end
  
  #
  # Remove leading and trailing whitespace
  #
  css = css.chomp.strip
end