/
rule_set.rb
658 lines (532 loc) · 22.5 KB
/
rule_set.rb
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# frozen_string_literal: true
require 'forwardable'
module CssParser
class RuleSet
# Patterns for specificity calculations
RE_ELEMENTS_AND_PSEUDO_ELEMENTS = /((^|[\s+>]+)\w+|:(first-line|first-letter|before|after))/i.freeze
RE_NON_ID_ATTRIBUTES_AND_PSEUDO_CLASSES = /(\.\w+)|(\[\w+)|(:(link|first-child|lang))/i.freeze
BACKGROUND_PROPERTIES = ['background-color', 'background-image', 'background-repeat', 'background-position', 'background-size', 'background-attachment'].freeze
LIST_STYLE_PROPERTIES = ['list-style-type', 'list-style-position', 'list-style-image'].freeze
FONT_STYLE_PROPERTIES = ['font-style', 'font-variant', 'font-weight', 'font-size', 'line-height', 'font-family'].freeze
BORDER_STYLE_PROPERTIES = ['border-width', 'border-style', 'border-color'].freeze
BORDER_PROPERTIES = ['border', 'border-left', 'border-right', 'border-top', 'border-bottom'].freeze
NUMBER_OF_DIMENSIONS = 4
DIMENSIONS = [
['margin', %w[margin-top margin-right margin-bottom margin-left]],
['padding', %w[padding-top padding-right padding-bottom padding-left]],
['border-color', %w[border-top-color border-right-color border-bottom-color border-left-color]],
['border-style', %w[border-top-style border-right-style border-bottom-style border-left-style]],
['border-width', %w[border-top-width border-right-width border-bottom-width border-left-width]]
].freeze
WHITESPACE_REPLACEMENT = '___SPACE___'
class Declarations
class Value
attr_reader :value
attr_accessor :important
def initialize(value, important: nil)
self.value = value
@important = important unless important.nil?
end
def value=(value)
value = value.to_s.sub(/\s*;\s*\Z/, '')
self.important = !value.slice!(CssParser::IMPORTANT_IN_PROPERTY_RX).nil?
value.strip!
raise ArgumentError, 'value is empty' if value.empty?
@value = value.freeze
end
def to_s
important ? "#{value} !important" : value
end
def ==(other)
return false unless other.is_a?(self.class)
value == other.value && important == other.important
end
end
extend Forwardable
def_delegators :declarations, :each
def initialize(declarations = {})
self.declarations = {}
declarations.each { |property, value| add_declaration!(property, value) }
end
# Add a CSS declaration
# @param [#to_s] property that should be added
# @param [Value, #to_s] value of the property
#
# @example
# declarations['color'] = 'blue'
#
# puts declarations['color']
# => #<CssParser::RuleSet::Declarations::Value:0x000000000305c730 @important=false, @order=1, @value="blue">
#
# @example
# declarations['margin'] = '0px auto !important'
#
# puts declarations['margin']
# => #<CssParser::RuleSet::Declarations::Value:0x00000000030c1838 @important=true, @order=2, @value="0px auto">
#
# If the property already exists its value will be over-written.
# If the value is empty - property will be deleted
def []=(property, value)
property = normalize_property(property)
if value.is_a?(Value)
declarations[property] = value
elsif value.to_s.strip.empty?
delete property
else
declarations[property] = Value.new(value)
end
end
alias add_declaration! []=
def [](property)
declarations[normalize_property(property)]
end
alias get_value []
def key?(property)
declarations.key?(normalize_property(property))
end
def size
declarations.size
end
# Remove CSS declaration
# @param [#to_s] property property to be removed
#
# @example
# declarations.delete('color')
def delete(property)
declarations.delete(normalize_property(property))
end
alias remove_declaration! delete
# Replace CSS property with multiple declarations
# @param [#to_s] property property name to be replaces
# @param [Hash<String => [String, Value]>] replacements hash with properties to replace with
#
# @example
# declarations = Declarations.new('line-height' => '0.25px', 'font' => 'small-caps', 'font-size' => '12em')
# declarations.replace_declaration!('font', {'line-height' => '1px', 'font-variant' => 'small-caps', 'font-size' => '24px'})
# declarations
# => #<CssParser::RuleSet::Declarations:0x00000000029c3018
# @declarations=
# {"line-height"=>#<CssParser::RuleSet::Declarations::Value:0x00000000038ac458 @important=false, @value="1px">,
# "font-variant"=>#<CssParser::RuleSet::Declarations::Value:0x00000000039b3ec8 @important=false, @value="small-caps">,
# "font-size"=>#<CssParser::RuleSet::Declarations::Value:0x00000000029c2c80 @important=false, @value="12em">}>
def replace_declaration!(property, replacements, preserve_importance: false)
property = normalize_property(property)
raise ArgumentError, "property #{property} does not exist" unless key?(property)
replacement_declarations = self.class.new(replacements)
if preserve_importance
importance = get_value(property).important
replacement_declarations.each { |_key, value| value.important = importance }
end
replacement_keys = declarations.keys
replacement_values = declarations.values
property_index = replacement_keys.index(property)
# We should preserve subsequent declarations of the same properties
# and prior important ones if replacement one is not important
replacements = replacement_declarations.each.with_object({}) do |(key, replacement), result|
existing = declarations[key]
# No existing -> set
unless existing
result[key] = replacement
next
end
# Replacement more important than existing -> replace
if replacement.important && !existing.important
result[key] = replacement
replaced_index = replacement_keys.index(key)
replacement_keys.delete_at(replaced_index)
replacement_values.delete_at(replaced_index)
property_index -= 1 if replaced_index < property_index
next
end
# Existing is more important than replacement -> keep
next if !replacement.important && existing.important
# Existing and replacement importance are the same,
# value which is declared later wins
result[key] = replacement if property_index > replacement_keys.index(key)
end
return if replacements.empty?
replacement_keys.delete_at(property_index)
replacement_keys.insert(property_index, *replacements.keys)
replacement_values.delete_at(property_index)
replacement_values.insert(property_index, *replacements.values)
self.declarations = replacement_keys.zip(replacement_values).to_h
end
def to_s(options = {})
str = declarations.reduce(String.new) do |memo, (prop, value)|
importance = options[:force_important] || value.important ? ' !important' : ''
memo << "#{prop}: #{value.value}#{importance}; "
end
# TODO: Clean-up regexp doesn't seem to work
str.gsub!(/^[\s^({)]+|[\n\r\f\t]*|\s+$/mx, '')
str.strip!
str
end
def ==(other)
return false unless other.is_a?(self.class)
declarations == other.declarations && declarations.keys == other.declarations.keys
end
protected
attr_reader :declarations
private
attr_writer :declarations
def normalize_property(property)
property = property.to_s.downcase
property.strip!
property
end
end
extend Forwardable
# Array of selector strings.
attr_reader :selectors
# Integer with the specificity to use for this RuleSet.
attr_accessor :specificity
# @!method add_declaration!
# @see CssParser::RuleSet::Declarations#add_declaration!
# @!method delete
# @see CssParser::RuleSet::Declarations#delete
def_delegators :declarations, :add_declaration!, :delete
alias []= add_declaration!
alias remove_declaration! delete
def initialize(selectors, block, specificity = nil)
@selectors = []
@specificity = specificity
parse_selectors!(selectors) if selectors
parse_declarations!(block)
end
# Get the value of a property
def get_value(property)
return '' unless (value = declarations[property])
"#{value};"
end
alias [] get_value
# Iterate through selectors.
#
# Options
# - +force_important+ -- boolean
#
# ==== Example
# ruleset.each_selector do |sel, dec, spec|
# ...
# end
def each_selector(options = {}) # :yields: selector, declarations, specificity
decs = declarations.to_s(options)
if @specificity
@selectors.each { |sel| yield sel.strip, decs, @specificity }
else
@selectors.each { |sel| yield sel.strip, decs, CssParser.calculate_specificity(sel) }
end
end
# Iterate through declarations.
def each_declaration # :yields: property, value, is_important
declarations.each do |property_name, value|
yield property_name, value.value, value.important
end
end
# Return all declarations as a string.
def declarations_to_s(options = {})
declarations.to_s(options)
end
# Return the CSS rule set as a string.
def to_s
"#{@selectors.join(',')} { #{declarations} }"
end
# Split shorthand declarations (e.g. +margin+ or +font+) into their constituent parts.
def expand_shorthand!
# border must be expanded before dimensions
expand_border_shorthand!
expand_dimensions_shorthand!
expand_font_shorthand!
expand_background_shorthand!
expand_list_style_shorthand!
end
# Convert shorthand background declarations (e.g. <tt>background: url("chess.png") gray 50% repeat fixed;</tt>)
# into their constituent parts.
#
# See http://www.w3.org/TR/CSS21/colors.html#propdef-background
def expand_background_shorthand! # :nodoc:
return unless (declaration = declarations['background'])
value = declaration.value.dup
replacement =
if value.match(CssParser::RE_INHERIT)
BACKGROUND_PROPERTIES.map { |key| [key, 'inherit'] }.to_h
else
{
'background-image' => value.slice!(CssParser::RE_IMAGE),
'background-attachment' => value.slice!(CssParser::RE_SCROLL_FIXED),
'background-repeat' => value.slice!(CssParser::RE_REPEAT),
'background-color' => value.slice!(CssParser::RE_COLOUR),
'background-size' => extract_background_size_from(value),
'background-position' => value.slice!(CssParser::RE_BACKGROUND_POSITION)
}
end
declarations.replace_declaration!('background', replacement, preserve_importance: true)
end
def extract_background_size_from(value)
size = value.slice!(CssParser::RE_BACKGROUND_SIZE)
size.sub(%r{^\s*/\s*}, '') if size
end
# Split shorthand border declarations (e.g. <tt>border: 1px red;</tt>)
# Additional splitting happens in expand_dimensions_shorthand!
def expand_border_shorthand! # :nodoc:
BORDER_PROPERTIES.each do |k|
next unless (declaration = declarations[k])
value = declaration.value.dup
replacement = {
"#{k}-width" => value.slice!(CssParser::RE_BORDER_UNITS),
"#{k}-color" => value.slice!(CssParser::RE_COLOUR),
"#{k}-style" => value.slice!(CssParser::RE_BORDER_STYLE)
}
declarations.replace_declaration!(k, replacement, preserve_importance: true)
end
end
# Split shorthand dimensional declarations (e.g. <tt>margin: 0px auto;</tt>)
# into their constituent parts. Handles margin, padding, border-color, border-style and border-width.
def expand_dimensions_shorthand! # :nodoc:
DIMENSIONS.each do |property, (top, right, bottom, left)|
next unless (declaration = declarations[property])
value = declaration.value.dup
# RGB and HSL values in borders are the only units that can have spaces (within params).
# We cheat a bit here by stripping spaces after commas in RGB and HSL values so that we
# can split easily on spaces.
#
# TODO: rgba, hsl, hsla
value.gsub!(RE_COLOUR) { |c| c.gsub(/(\s*,\s*)/, ',') }
value.gsub!(RE_FUNCTIONS) { |c| c.gsub(/\s+/, WHITESPACE_REPLACEMENT) }
matches = value.strip.split(/\s+/)
case matches.length
when 1
values = matches.to_a * 4
when 2
values = matches.to_a * 2
when 3
values = matches.to_a
values << matches[1] # left = right
when 4
values = matches.to_a
else
raise ArgumentError, "Cannot parse #{value}"
end
t, r, b, l = values
replacement = {top => t, right => r, bottom => b, left => l}.each_with_object({}) do |(key, replacement_value), memo|
memo[key] = replacement_value.gsub(WHITESPACE_REPLACEMENT, ' ')
end
declarations.replace_declaration!(property, replacement, preserve_importance: true)
end
end
# Convert shorthand font declarations (e.g. <tt>font: 300 italic 11px/14px verdana, helvetica, sans-serif;</tt>)
# into their constituent parts.
def expand_font_shorthand! # :nodoc:
return unless (declaration = declarations['font'])
# reset properties to 'normal' per http://www.w3.org/TR/CSS21/fonts.html#font-shorthand
font_props = {
'font-style' => 'normal',
'font-variant' => 'normal',
'font-weight' => 'normal',
'font-size' => 'normal',
'line-height' => 'normal'
}
value = declaration.value.dup
value.gsub!(%r{/\s+}, '/') # handle spaces between font size and height shorthand (e.g. 14px/ 16px)
in_fonts = false
matches = value.scan(/"(?:.*[^"])"|'(?:.*[^'])'|(?:\w[^ ,]+)/)
matches.each do |m|
m.strip!
m.gsub!(/;$/, '')
if in_fonts
if font_props.key?('font-family')
font_props['font-family'] += ", #{m}"
else
font_props['font-family'] = m
end
elsif m =~ /normal|inherit/i
['font-style', 'font-weight', 'font-variant'].each do |font_prop|
font_props[font_prop] ||= m
end
elsif m =~ /italic|oblique/i
font_props['font-style'] = m
elsif m =~ /small-caps/i
font_props['font-variant'] = m
elsif m =~ /[1-9]00$|bold|bolder|lighter/i
font_props['font-weight'] = m
elsif m =~ CssParser::FONT_UNITS_RX
if m.include?('/')
font_props['font-size'], font_props['line-height'] = m.split('/', 2)
else
font_props['font-size'] = m
end
in_fonts = true
end
end
declarations.replace_declaration!('font', font_props, preserve_importance: true)
end
# Convert shorthand list-style declarations (e.g. <tt>list-style: lower-alpha outside;</tt>)
# into their constituent parts.
#
# See http://www.w3.org/TR/CSS21/generate.html#lists
def expand_list_style_shorthand! # :nodoc:
return unless (declaration = declarations['list-style'])
value = declaration.value.dup
replacement =
if value =~ CssParser::RE_INHERIT
LIST_STYLE_PROPERTIES.map { |key| [key, 'inherit'] }.to_h
else
{
'list-style-type' => value.slice!(CssParser::RE_LIST_STYLE_TYPE),
'list-style-position' => value.slice!(CssParser::RE_INSIDE_OUTSIDE),
'list-style-image' => value.slice!(CssParser::URI_RX_OR_NONE)
}
end
declarations.replace_declaration!('list-style', replacement, preserve_importance: true)
end
# Create shorthand declarations (e.g. +margin+ or +font+) whenever possible.
def create_shorthand!
create_background_shorthand!
create_dimensions_shorthand!
# border must be shortened after dimensions
create_border_shorthand!
create_font_shorthand!
create_list_style_shorthand!
end
# Combine several properties into a shorthand one
def create_shorthand_properties!(properties, shorthand_property) # :nodoc:
values = []
properties_to_delete = []
properties.each do |property|
next unless (declaration = declarations[property])
next if declaration.important
values << declaration.value
properties_to_delete << property
end
return if values.length <= 1
properties_to_delete.each do |property|
declarations.delete(property)
end
declarations[shorthand_property] = values.join(' ')
end
# Looks for long format CSS background properties (e.g. <tt>background-color</tt>) and
# converts them into a shorthand CSS <tt>background</tt> property.
#
# Leaves properties declared !important alone.
def create_background_shorthand! # :nodoc:
# When we have a background-size property we must separate it and distinguish it from
# background-position by preceding it with a backslash. In this case we also need to
# have a background-position property, so we set it if it's missing.
# http://www.w3schools.com/cssref/css3_pr_background.asp
if (declaration = declarations['background-size']) && !declaration.important
declarations['background-position'] ||= '0% 0%'
declaration.value = "/ #{declaration.value}"
end
create_shorthand_properties! BACKGROUND_PROPERTIES, 'background'
end
# Combine border-color, border-style and border-width into border
# Should be run after create_dimensions_shorthand!
#
# TODO: this is extremely similar to create_background_shorthand! and should be combined
def create_border_shorthand! # :nodoc:
values = []
BORDER_STYLE_PROPERTIES.each do |property|
next unless (declaration = declarations[property])
next if declaration.important
# can't merge if any value contains a space (i.e. has multiple values)
# we temporarily remove any spaces after commas for the check (inside rgba, etc...)
return nil if declaration.value.gsub(/,\s/, ',').strip =~ /\s/
values << declaration.value
declarations.delete(property)
end
return if values.empty?
declarations['border'] = values.join(' ')
end
# Looks for long format CSS dimensional properties (margin, padding, border-color, border-style and border-width)
# and converts them into shorthand CSS properties.
def create_dimensions_shorthand! # :nodoc:
return if declarations.size < NUMBER_OF_DIMENSIONS
DIMENSIONS.each do |property, dimensions|
values = [:top, :right, :bottom, :left].each_with_index.with_object({}) do |(side, index), result|
next unless (declaration = declarations[dimensions[index]])
result[side] = declaration.value
end
# All four dimensions must be present
next if values.size != dimensions.size
new_value = values.values_at(*compute_dimensions_shorthand(values)).join(' ').strip
declarations[property] = new_value unless new_value.empty?
# Delete the longhand values
dimensions.each { |d| declarations.delete(d) }
end
end
# Looks for long format CSS font properties (e.g. <tt>font-weight</tt>) and
# tries to convert them into a shorthand CSS <tt>font</tt> property. All
# font properties must be present in order to create a shorthand declaration.
def create_font_shorthand! # :nodoc:
return unless FONT_STYLE_PROPERTIES.all? { |prop| declarations.key?(prop) }
new_value = String.new
['font-style', 'font-variant', 'font-weight'].each do |property|
unless declarations[property].value == 'normal'
new_value << declarations[property].value << ' '
end
end
new_value << declarations['font-size'].value
unless declarations['line-height'].value == 'normal'
new_value << '/' << declarations['line-height'].value
end
new_value << ' ' << declarations['font-family'].value
declarations['font'] = new_value.gsub(/\s+/, ' ')
FONT_STYLE_PROPERTIES.each { |prop| declarations.delete(prop) }
end
# Looks for long format CSS list-style properties (e.g. <tt>list-style-type</tt>) and
# converts them into a shorthand CSS <tt>list-style</tt> property.
#
# Leaves properties declared !important alone.
def create_list_style_shorthand! # :nodoc:
create_shorthand_properties! LIST_STYLE_PROPERTIES, 'list-style'
end
private
attr_accessor :declarations
def compute_dimensions_shorthand(values)
# All four sides are equal, returning single value
return [:top] if values.values.uniq.count == 1
# `/* top | right | bottom | left */`
return [:top, :right, :bottom, :left] if values[:left] != values[:right]
# Vertical are the same & horizontal are the same, `/* vertical | horizontal */`
return [:top, :left] if values[:top] == values[:bottom]
[:top, :left, :bottom]
end
def parse_declarations!(block) # :nodoc:
self.declarations = Declarations.new
return unless block
continuation = nil
block.split(/[;$]+/m).each do |decs|
decs = (continuation ? continuation + decs : decs)
if decs =~ /\([^)]*\Z/ # if it has an unmatched parenthesis
continuation = "#{decs};"
elsif (matches = decs.match(/\s*(.[^:]*)\s*:\s*(.+?)(?:;?\s*\Z)/i))
# skip end_of_declaration
property = matches[1]
value = matches[2]
add_declaration!(property, value)
continuation = nil
end
end
end
#--
# TODO: way too simplistic
#++
def parse_selectors!(selectors) # :nodoc:
@selectors = selectors.split(',').map do |s|
s.gsub!(/\s+/, ' ')
s.strip!
s
end
end
end
class OffsetAwareRuleSet < RuleSet
# File offset range
attr_reader :offset
# the local or remote location
attr_accessor :filename
def initialize(filename, offset, selectors, block, specificity = nil)
super(selectors, block, specificity)
@offset = offset
@filename = filename
end
end
end