Class: Csscss::RedundancyAnalyzer

Inherits:
Object
  • Object
show all
Defined in:
lib/csscss/redundancy_analyzer.rb

Instance Method Summary collapse

Constructor Details

#initialize(raw_css) ⇒ RedundancyAnalyzer 



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# File 'lib/csscss/redundancy_analyzer.rb', line 4

def initialize(raw_css)
  @raw_css = raw_css
end

Instance Method Details

#redundancies(opts = {}) ⇒ Object 



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# File 'lib/csscss/redundancy_analyzer.rb', line 8

def redundancies(opts = {})
  minimum            = opts[:minimum]
  ignored_properties = opts[:ignored_properties] || []
  ignored_selectors  = opts[:ignored_selectors] || []
  match_shorthand    = opts.fetch(:match_shorthand, true)

  rule_sets = Parser::Css.parse(@raw_css)
  matches = {}
  parents = {}
  rule_sets.each do |rule_set|
    next if ignored_selectors.include?(rule_set.selectors.selectors)
    sel = rule_set.selectors

    rule_set.declarations.each do |dec|
      next if ignored_properties.include?(dec.property)

      if match_shorthand && parser = shorthand_parser(dec.property)
        if new_decs = parser.parse(dec.property, dec.value)
          if dec.property == "border"
            %w(border-top border-right border-bottom border-left).each do |property|
              border_dec = Declaration.new(property, dec.value)
              parents[border_dec] ||= []
              (parents[border_dec] << dec).uniq!
              border_dec.parents = parents[border_dec]

              matches[border_dec] ||= []
              matches[border_dec] << sel
              matches[border_dec].uniq!
            end
          end

          new_decs.each do |new_dec|
            # replace any non-derivatives with derivatives
            existing = matches.delete(new_dec) || []
            existing << sel
            parents[new_dec] ||= []
            (parents[new_dec] << dec).uniq!
            new_dec.parents = parents[new_dec]
            matches[new_dec] = existing
            matches[new_dec].uniq!
          end
        end
      end

      matches[dec] ||= []
      matches[dec] << sel
      matches[dec].uniq!
    end
  end

  inverted_matches = {}
  matches.each do |declaration, selector_groups|
    if selector_groups.size > 1
      selector_groups.combination(2).each do |two_selectors|
        inverted_matches[two_selectors] ||= []
        inverted_matches[two_selectors] << declaration
      end
    end
  end

  # trims any derivative declarations alongside shorthand
  inverted_matches.each do |selectors, declarations|
    redundant_derivatives = declarations.select do |dec|
      dec.derivative? && declarations.detect {|dec2| dec2 > dec }
    end
    unless redundant_derivatives.empty?
      inverted_matches[selectors] = declarations - redundant_derivatives
    end

    # border needs to be reduced even more
    %w(width style color).each do |property|
      decs = inverted_matches[selectors].select do |dec|
        dec.derivative? && dec.property =~ /border-\w+-#{property}/
      end
      if decs.size == 4 && decs.map(&:value).uniq.size == 1
        inverted_matches[selectors] -= decs
        inverted_matches[selectors] << Declaration.new("border-#{property}", decs.first.value)
      end
    end
  end

  if minimum
    inverted_matches.delete_if do |key, declarations|
      declarations.size < minimum
    end
  end

  # combines selector keys by common declarations
  final_inverted_matches = inverted_matches.dup
  inverted_matches.to_a.each_with_index do |(selector_group1, declarations1), index|
    keys = [selector_group1]
    inverted_matches.to_a[(index + 1)..-1].each do |selector_group2, declarations2|
      if declarations1 == declarations2 && final_inverted_matches[selector_group2]
        keys << selector_group2
        final_inverted_matches.delete(selector_group2)
      end
    end

    if keys.size > 1
      final_inverted_matches.delete(selector_group1)
      key = keys.flatten.sort.uniq
      final_inverted_matches[key] = declarations1
    end
  end

  # sort hash by number of matches
  sorted_array = final_inverted_matches.sort {|(_, v1), (_, v2)| v2.size <=> v1.size }
  {}.tap do |sorted_hash|
    sorted_array.each do |key, value|
      sorted_hash[key.sort] = value.sort
    end
  end
end