module CssParser

Constants

VERSION

Public Class Methods

calculate_specificity(selector) click to toggle source

Calculates the specificity of a CSS selector per www.w3.org/TR/CSS21/cascade.html#specificity

Returns an integer.

Example ↑

CssParser.calculate_specificity('#content div p:first-line a:link')
=> 114
# File lib/css_parser.rb, line 112
def self.calculate_specificity(selector)
  a = 0
  b = selector.scan(/\#/).length
  c = selector.scan(NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX_NC).length
  d = selector.scan(ELEMENTS_AND_PSEUDO_ELEMENTS_RX_NC).length

  "#{a}#{b}#{c}#{d}".to_i
rescue
  0
end
convert_uris(css, base_uri) click to toggle source

Make url() links absolute.

Takes a block of CSS and returns it with all relative URIs converted to absolute URIs.

“For CSS style sheets, the base URI is that of the style sheet, not that of the source document.” per www.w3.org/TR/CSS21/syndata.html#uri

Returns a string.

Example ↑

CssParser.convert_uris("body { background: url('../style/yellow.png?abc=123') };",
             "http://example.org/style/basic.css").inspect
=> "body { background: url('http://example.org/style/yellow.png?abc=123') };"
# File lib/css_parser.rb, line 136
def self.convert_uris(css, base_uri)
  base_uri = Addressable::URI.parse(base_uri) unless base_uri.is_a?(Addressable::URI)

  css.gsub(URI_RX) do
    uri = Regexp.last_match(1).to_s.gsub(/["']+/, '')
    # Don't process URLs that are already absolute
    unless uri.match(%r{^[a-z]+://}i)
      begin
        uri = base_uri.join(uri)
      rescue
        nil
      end
    end
    "url('#{uri}')"
  end
end
merge(*rule_sets) click to toggle source

Merge multiple CSS RuleSets by cascading according to the CSS 2.1 cascading rules (www.w3.org/TR/REC-CSS2/cascade.html#cascading-order).

Takes one or more RuleSet objects.

Returns a RuleSet.

Cascading ↑

If a RuleSet object has its specificity defined, that specificity is used in the cascade calculations.

If no specificity is explicitly set and the RuleSet has one selector, the specificity is calculated using that selector.

If no selectors the specificity is treated as 0.

If multiple selectors are present then the greatest specificity is used.

Example #1 ↑

rs1 = RuleSet.new(nil, 'color: black;')
rs2 = RuleSet.new(nil, 'margin: 0px;')

merged = CssParser.merge(rs1, rs2)

puts merged
=> "{ margin: 0px; color: black; }"

Example #2 ↑

rs1 = RuleSet.new(nil, 'background-color: black;')
rs2 = RuleSet.new(nil, 'background-image: none;')

merged = CssParser.merge(rs1, rs2)

puts merged
=> "{ background: none black; }"
# File lib/css_parser.rb, line 55
def self.merge(*rule_sets)
  @folded_declaration_cache = {}

  # in case called like CssParser.merge([rule_set, rule_set])
  rule_sets.flatten! if rule_sets[0].is_a?(Array)

  unless rule_sets.all? { |rs| rs.is_a?(CssParser::RuleSet) }
    raise ArgumentError, 'all parameters must be CssParser::RuleSets.'
  end

  return rule_sets[0] if rule_sets.length == 1

  # Internal storage of CSS properties that we will keep
  properties = {}

  rule_sets.each do |rule_set|
    rule_set.expand_shorthand!

    specificity = rule_set.specificity
    specificity ||= rule_set.selectors.map { |s| calculate_specificity(s) }.compact.max || 0

    rule_set.each_declaration do |property, value, is_important|
      # Add the property to the list to be folded per http://www.w3.org/TR/CSS21/cascade.html#cascading-order
      if not properties.key?(property)
        properties[property] = {value: value, specificity: specificity, is_important: is_important}
      elsif is_important
        if not properties[property][:is_important] or properties[property][:specificity] <= specificity
          properties[property] = {value: value, specificity: specificity, is_important: is_important}
        end
      elsif properties[property][:specificity] < specificity or properties[property][:specificity] == specificity
        unless properties[property][:is_important]
          properties[property] = {value: value, specificity: specificity, is_important: is_important}
        end
      end
    end
  end

  merged = properties.each_with_object(RuleSet.new(nil, nil)) do |(property, details), rule_set|
    value = details[:value].strip
    rule_set[property.strip] = details[:is_important] ? "#{value.gsub(/;\Z/, '')}!important" : value
  end

  merged.create_shorthand!
  merged
end
regex_possible_values(*values) click to toggle source 
# File lib/css_parser/regexps.rb, line 4
def self.regex_possible_values(*values)
  Regexp.new("([\s]*^)?(#{values.join('|')})([\s]*$)?", 'i')
end
sanitize_media_query(raw) click to toggle source 
# File lib/css_parser.rb, line 153
def self.sanitize_media_query(raw)
  mq = raw.to_s.gsub(/\s+/, ' ')
  mq.strip!
  mq = 'all' if mq.empty?
  mq.to_sym
end