Class: YuiCompressor::Yui

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

Overview

Compress CSS rules using a variety of techniques

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Yui

Instantiate compressor



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

def initialize
  @preserved_tokens = []
  @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/conductor/yui_compressor.rb', line 9

def input_size
  @input_size
end

#output_size ⇒ Object (readonly)

Returns the value of attribute output_size.



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

def output_size
  @output_size
end

Instance Method Details

#compress(css, line_length = 0) ⇒ Object

YUI Compress string

Parameters:

  • css (String) —

    The css

  • line_length (Integer) (defaults to: 0) —

    The line length



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# File 'lib/conductor/yui_compressor.rb', line 29

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!(%r{\*/ }, "*/")

  # 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|(?:(?:webkit|moz|o|ms)-)?transform-origin):0(;|\})/i) do
    "#{::Regexp.last_match(1).downcase}:0 0#{::Regexp.last_match(2)}"
  end

  # 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|
    "#".dup << ::Regexp.last_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')

  # border: none -> border:0
  css.gsub!(/(border|border-(top|right|bottom)|outline|background):none(;|\})/i) do
    "#{::Regexp.last_match(1).downcase}:0#{::Regexp.last_match(2)}"
  end

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

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

  if line_length.positive?
    # 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.
    start_index = 0
    idx = 0
    length = css.length
    while idx < length
      idx += 1
      if css[idx - 1, 1] == "}" && idx - start_index > line_length
        css = "#{css.slice(0, idx)}\n#{css.slice(idx, length)}"
        start_index = idx
      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) ⇒ String

Replace comments and strings with placeholders

Parameters:

  • css_text (String) —

    The css text

Returns:

  • (String) —

    css text with strings replaced



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# File 'lib/conductor/yui_compressor.rb', line 139

def process_comments_and_strings(css_text)
  css = css_text.dup.clean_encode

  start_index = 0
  token = ""
  totallen = css.length
  placeholder = ""

  # collect all comment blocks
  while (start_index = css.index(%r{/\*}, start_index))
    end_index = css.index(%r{\*/}, start_index + 2)
    end_index ||= totallen
    token = css.slice(start_index + 2..end_index - 1)
    @comments.push(token)
    css =  "#{css.slice(0..start_index + 1)}___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{@comments.length - 1}___#{css.slice(end_index, totallen)}"
    start_index += 2
  end

  # preserve strings so their content doesn't get accidentally minified
  css = 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 |idx|
        string.gsub!(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{idx}___/, @comments[idx])
      end
    end

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

    "#{quote}___YUICSSMIN_PRESERVED_TOKEN_#{@preserved_tokens.length - 1}___#{quote}"
  end

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

    token = @comments[idx]
    placeholder = "___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{idx}___"

    # ! in the first position of the comment means preserve
    # so push to the preserved tokens keeping the !
    if token[0, 1] == "!"
      @preserved_tokens.push(token)
      css.gsub!(/#{placeholder}/i, "___YUICSSMIN_PRESERVED_TOKEN_#{@preserved_tokens.length - 1}___")
      next
    end

    # # \ in the last position looks like hack for Mac/IE5
    # # shorten that to /*\*/ and the next one to /**/
    # if token[-1, 1] == "\\"
    #   @preserved_tokens.push("\\")
    #   css.gsub!(/#{placeholder}/, "___YUICSSMIN_PRESERVED_TOKEN_#{@preserved_tokens.length - 1}___")
    #   # keep the next comment but remove its content
    #   @preserved_tokens.push("")
    #   css.gsub!(/___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_#{idx + 1}___/,
    #             "___YUICSSMIN_PRESERVED_TOKEN_#{@preserved_tokens.length - 1}___")
    #   ie5_hack = true
    #   next
    # end

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

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

  css
end

#restore_preserved_comments_and_strings(clean_css) ⇒ String

Restore saved comments and strings

Parameters:

  • clean_css (String) —

    The processed css

Returns:



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# File 'lib/conductor/yui_compressor.rb', line 232

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

    end_index = start_index + placeholder.length

    css = css.slice(0..start_index - 1).to_s + @preserved_tokens[idx] + css.slice(end_index, css_length).to_s
  end

  css
end