Module: CssParser

Defined in:
lib/css_parser.rb,
lib/css_parser/parser.rb,
lib/css_parser/regexps.rb,
lib/css_parser/rule_set.rb

Defined Under Namespace

Classes: CircularReferenceError, Parser, RemoteFileError, RuleSet

Constant Summary collapse

VERSION = 
'1.1.0'
RE_NL =

:stopdoc: Base types

Regexp.new('(\n|\r\n|\r|\f)')
RE_NON_ASCII =
^0-177 
Regexp.new('([\x00-\xFF])', Regexp::IGNORECASE, 'n')
RE_UNICODE = 
Regexp.new('(\\\\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])*)', Regexp::IGNORECASE | Regexp::EXTENDED | Regexp::MULTILINE, 'n')
RE_ESCAPE = 
Regexp.union(RE_UNICODE, '|(\\\\[^\n\r\f0-9a-f])')
RE_IDENT = 
Regexp.new("[\-]?([_a-z]|#{RE_NON_ASCII}|#{RE_ESCAPE})([_a-z0-9\-]|#{RE_NON_ASCII}|#{RE_ESCAPE})*", Regexp::IGNORECASE, 'n')
RE_STRING1 =

General strings

Regexp.new('(\"(.[^\n\r\f\\"]*|\\\\' + RE_NL.to_s + '|' + RE_ESCAPE.to_s + ')*\")')
RE_STRING2 = 
Regexp.new('(\'(.[^\n\r\f\\\']*|\\\\' + RE_NL.to_s + '|' + RE_ESCAPE.to_s + ')*\')')
RE_STRING = 
Regexp.union(RE_STRING1, RE_STRING2)
RE_URI = 
Regexp.new('(url\([\s]*([\s]*' + RE_STRING.to_s + '[\s]*)[\s]*\))|(url\([\s]*([!#$%&*\-~]|' + RE_NON_ASCII.to_s + '|' + RE_ESCAPE.to_s + ')*[\s]*)\)', Regexp::IGNORECASE | Regexp::EXTENDED  | Regexp::MULTILINE, 'n')
URI_RX = 
/url\(("([^"]*)"|'([^']*)'|([^)]*))\)/im
RE_AT_IMPORT_RULE =

Initial parsing

/\@import[\s]+(url\()?["']+(.[^'"]*)["']\)?([\w\s\,]*);?/i
IMPORTANT_IN_PROPERTY_RX =

RE_AT_IMPORT_RULE = Regexp.new(‘@import*(’ + RE_STRING.to_s + ‘)([ws,]*)?’, Regexp::IGNORECASE) – should handle url() even though it is not allowed ++

/[\s]*\!important[\s]*/i
STRIP_CSS_COMMENTS_RX = 
/\/\*.*?\*\//m
STRIP_HTML_COMMENTS_RX = 
/\<\!\-\-|\-\-\>/m
BOX_MODEL_UNITS_RX =

Special units

/(auto|inherit|0|([\-]*([0-9]+|[0-9]*\.[0-9]+)(e[mx]+|px|[cm]+m|p[tc+]|in|\%)))([\s;]|\Z)/imx
RE_LENGTH_OR_PERCENTAGE = 
Regexp.new('([\-]*(([0-9]*\.[0-9]+)|[0-9]+)(e[mx]+|px|[cm]+m|p[tc+]|in|\%))', Regexp::IGNORECASE)
RE_BACKGROUND_POSITION = 
Regexp.new("((#{RE_LENGTH_OR_PERCENTAGE})|left|center|right|top|bottom)", Regexp::IGNORECASE | Regexp::EXTENDED)
FONT_UNITS_RX = 
/(([x]+\-)*small|medium|large[r]*|auto|inherit|([0-9]+|[0-9]*\.[0-9]+)(e[mx]+|px|[cm]+m|p[tc+]|in|\%)*)/i
ELEMENTS_AND_PSEUDO_ELEMENTS_RX =

Patterns for specificity calculations

/((^|[\s\+\>]+)[\w]+|\:(first\-line|first\-letter|before|after))/i
NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX = 
/(\.[\w]+)|(\[[\w]+)|(\:(link|first\-child|lang))/i
RE_COLOUR_RGB =

Colours

Regexp.new('(rgb[\s]*\([\s-]*[\d]+(\.[\d]+)?[%\s]*,[\s-]*[\d]+(\.[\d]+)?[%\s]*,[\s-]*[\d]+(\.[\d]+)?[%\s]*\))', Regexp::IGNORECASE)
RE_COLOUR_HEX = 
/(#([0-9a-f]{6}|[0-9a-f]{3})([\s;]|$))/i
RE_COLOUR_NAMED = 
/([\s]*^)?(aqua|black|blue|fuchsia|gray|green|lime|maroon|navy|olive|orange|purple|red|silver|teal|white|yellow|transparent)([\s]*$)?/i
RE_COLOUR = 
Regexp.union(RE_COLOUR_RGB, RE_COLOUR_HEX, RE_COLOUR_NAMED)

Class Method Summary collapse

Class Method Details

.calculate_specificity(selector) ⇒ Object

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

– Thanks to Rafael Salazar and Nick Fitzsimons on the css-discuss list for their help. ++



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# File 'lib/css_parser.rb', line 106

def CssParser.calculate_specificity(selector)
  a = 0
  b = selector.scan(/\#/).length
  c = selector.scan(NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES_RX).length
  d = selector.scan(ELEMENTS_AND_PSEUDO_ELEMENTS_RX).length

  (a.to_s + b.to_s + c.to_s + d.to_s).to_i
rescue
  return 0
end

.convert_uris(css, base_uri) ⇒ Object

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') };"



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# File 'lib/css_parser.rb', line 130

def self.convert_uris(css, base_uri)
  out = ''
  base_uri = URI.parse(base_uri) unless base_uri.kind_of?(URI)

  out = css.gsub(URI_RX) do |s|
    uri = $1.to_s
    uri.gsub!(/["']+/, '')
    # Don't process URLs that are already absolute
    unless uri =~ /^[a-z]+\:\/\//i
      begin
        uri = base_uri.merge(uri) 
      rescue; end
    end
    "url('" + uri.to_s + "')"
  end
  out
end

.merge(*rule_sets) ⇒ Object

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 or multiple selectors are present, the specificity is treated as 0.

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; }"

– TODO: declaration_hashes should be able to contain a RuleSet

this should be a Class method



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# File 'lib/css_parser.rb', line 46

def CssParser.merge(*rule_sets)
  @folded_declaration_cache = {}

  # in case called like CssParser.merge([rule_set, rule_set])
  rule_sets.flatten! if rule_sets[0].kind_of?(Array)
  
  unless rule_sets.all? {|rs| rs.kind_of?(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
    unless specificity
      if rule_set.selectors.length == 1
        specificity = calculate_specificity(rule_set.selectors[0])
      else
        specificity = 0
      end
    end

    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.has_key?(property) or
             is_important or # step 2
             properties[property][:specificity] < specificity or # step 3
             properties[property][:specificity] == specificity # step 4    
        properties[property] = {:value => value, :specificity => specificity, :is_important => is_important}            
      end
    end
  end

  merged = RuleSet.new(nil, nil)

  # TODO: what about important
  properties.each do |property, details|
    merged[property.strip] = details[:value].strip
  end

  merged.create_shorthand!
  merged
end