Class: YuiCompressor::Yui

Inherits:
Object
  • Object
show all
Defined in:
lib/modules/yui_compressor.rb

Overview

Compress CSS rules using a variety of techniques

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Yui

Returns a new instance of Yui.



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# File 'lib/modules/yui_compressor.rb', line 9

def initialize()
  @preservedTokens = []
  @comments = []
			@input_size = 0
			@output_size = 0
end

Instance Attribute Details

#input_size ⇒ Object (readonly)

Returns the value of attribute input_size.



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# File 'lib/modules/yui_compressor.rb', line 8

def input_size
  @input_size
end

#output_size ⇒ Object (readonly)

Returns the value of attribute output_size.



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# File 'lib/modules/yui_compressor.rb', line 8

def output_size
  @output_size
end

Instance Method Details

#compress(css, line_length = 0) ⇒ Object 



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# File 'lib/modules/yui_compressor.rb', line 16

def compress(css, line_length=0)
			@input_size = css.length

  css = process_comments_and_strings(css)

  # Normalize all whitespace strings to single spaces. Easier to work with that way.
  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.gsub!(/(?:^|\})[^\{:]+\s+:+[^\{]*\{/) do |match|
    match.gsub(':', '___PSEUDOCLASSCOLON___')
  end
  css.gsub!(/\s+([!\{\};:>+\(\)\],])/, '\1')
  css.gsub!(/([!\{\}:;>+\(\[,])\s+/, '\1')
  css.gsub!('___PSEUDOCLASSCOLON___', ':')

  # special case for IE
  css.gsub!(/:first-(line|letter)(\{|,)/, ':first-\1 \2')

  # no space after the end of a preserved comment
  css.gsub!(/\*\/ /, '*/')

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

  # Put the space back in some cases, to support stuff like
  # @media screen and (-webkit-min-device-pixel-ratio:0){
  css.gsub!(/\band\(/i, "and (")

  # remove unnecessary semicolons
  css.gsub!(/;+\}/, '}')

  # Replace 0(%, em, ex, px, in, cm, mm, pt, pc) with just 0.
  css.gsub!(/([\s:])([+-]?0)(?:%|em|ex|px|in|cm|mm|pt|pc)/i, '\1\2')

  # Replace 0 0 0 0; with 0.
  css.gsub!(/:(?:0 )+0(;|\})/, ':0\1')

  # Restore background-position:0 0; if required
  css.gsub!(/background-position:0(;|\})/i, 'background-position:0 0\1')

  # Replace 0.6 with .6, but only when preceded by : or a space.
  css.gsub!(/(:|\s)0+\.(\d+)/, '\1.\2')

  # 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.gsub!(/rgb\s*\(\s*([0-9,\s]+)\s*\)/) do |match|
    '#' << $1.scan(/\d+/).map{|n| n.to_i.to_s(16).rjust(2, '0') }.join
  end

  # 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.
  css.gsub!(/([^"'=\s])(\s?)\s*#([0-9a-f])\3([0-9a-f])\4([0-9a-f])\5/i, '\1\2#\3\4\5')

  # shorter opacity IE filter
  css.gsub!(/progid:DXImageTransform\.Microsoft\.Alpha\(Opacity=/i, "alpha(opacity=")

  # Remove empty rules.
  css.gsub!(/[^\};\{\/]+\{\}/, '')

 if (line_length > 0)
   # 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.
   startIndex = 0
   index = 0
length = css.length
   while (index < length)
     index += 1
     if (css[index - 1,1] === '}' && index - startIndex > line_length)
       css = css.slice(0, index) + "\n" + css.slice(index, length)
       startIndex = index
     end
   end
 end

 # Replace multiple semi-colons in a row by a single one
 # See SF bug #1980989
 css.gsub!(/[;]+/, ';')

  #restore preserved comments and strings
			css = restore_preserved_comments_and_strings(css)

  # top and tail whitespace
  css.strip!

			@output_size = css.length
  css
end

#process_comments_and_strings(css_text) ⇒ Object 



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# File 'lib/modules/yui_compressor.rb', line 113

def process_comments_and_strings(css_text)
  css = css_text.clone

  startIndex = 0
  endIndex = 0
  i = 0
  max = 0
  token = ''
  totallen = css.length
  placeholder = ''

  # collect all comment blocks
  while (startIndex = css.index(/\/\*/, startIndex))
    endIndex = css.index(/\*\//, startIndex + 2)
    unless endIndex
      endIndex = totallen
    end
    token = css.slice(startIndex+2..endIndex-1)
    @comments.push(token)
    css = css.slice(0..startIndex+1).to_s + "___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + (@comments.length - 1).to_s + "___" + css.slice(endIndex, totallen).to_s
    startIndex += 2
  end

  # preserve strings so their content doesn't get accidentally minified
  css.gsub!(/("([^\\"]|\\.|\\)*")|('([^\\']|\\.|\\)*')/) do |match|
    quote = match[0,1]
    string = match.slice(1..-2)

    # maybe the string contains a comment-like substring?
    # one, maybe more? put'em back then
    if string =~ /___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_/
      @comments.each_index do |index|
        string.gsub!(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{index.to_s}___/, @comments[index])
      end
    end

    # minify alpha opacity in filter strings
    string.gsub!(/progid:DXImageTransform\.Microsoft\.Alpha\(Opacity=/i, "alpha(opacity=")
    @preservedTokens.push(string)

    quote + "___YUICSSMIN_PRESERVED_TOKEN_" + (@preservedTokens.length - 1).to_s + "___" + quote
  end

  # used to jump one index in loop
  ie5_hack = false
  # strings are safe, now wrestle the comments
  @comments.each_index do |index|
    if ie5_hack
      ie5_hack = false
      next
    end

    token = @comments[index]
    placeholder = "___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_" + index.to_s + "___"

    # ! in the first position of the comment means preserve
    # so push to the preserved tokens keeping the !
    if (token[0,1] === "!")
      @preservedTokens.push(token)
      css.gsub!( /#{placeholder}/i,  "___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[-1,1] === "\\")
      @preservedTokens.push("\\")
      css.gsub!( /#{placeholder}/,  "___YUICSSMIN_PRESERVED_TOKEN_" + (@preservedTokens.length - 1).to_s + "___")
      # keep the next comment but remove its content
      @preservedTokens.push("")
      css.gsub!(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{index+1}___/,  "___YUICSSMIN_PRESERVED_TOKEN_" + (@preservedTokens.length - 1).to_s + "___")
      ie5_hack = true
      next
    end

    # keep empty comments after child selectors (IE7 hack)
    # e.g. html >/**/ body
    if ((token.length === 0) && (startIndex = css.index( /#{placeholder}/)))
      if (startIndex > 2)
        if (css[startIndex - 3,1] === '>')
          @preservedTokens.push("")
          css.gsub!(/#{placeholder}/,  "___YUICSSMIN_PRESERVED_TOKEN_" + (@preservedTokens.length - 1).to_s + "___")
        end
      end
    end

    # in all other cases kill the comment
    css.gsub!( /\/\*#{placeholder}\*\//, "")
  end

  css
end

#restore_preserved_comments_and_strings(clean_css) ⇒ Object 



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# File 'lib/modules/yui_compressor.rb', line 206

def restore_preserved_comments_and_strings(clean_css)
	css = clean_css.clone
    css_length = css.length
    @preservedTokens.each_index do |index|
      # slice these back into place rather than regex, because
      # complex nested strings cause the replacement to fail
      placeholder = "___YUICSSMIN_PRESERVED_TOKEN_#{index}___"
      startIndex = css.index(placeholder, 0)
		next unless startIndex # skip if nil
      endIndex = startIndex + placeholder.length

      css = css.slice(0..startIndex-1).to_s + @preservedTokens[index] + css.slice(endIndex, css_length).to_s
    end

	css
end