Module: MiniCSS::Sel

Defined in:
lib/minicss/sel.rb

Constant Summary collapse

PLACEHOLDER_CHAR = 
""
ESCAPE_SENTINEL = 
"\uE000"
STRING_SENTINEL = 
"\uE001"
TOKENS = 
{
  attribute: /\[\s*(?:(?<namespace>\*|[-\w\p{^ASCII}]*)\|)?(?<name>[-\w\p{^ASCII}]+)\s*(?:(?<operator>\W?=)\s*(?<value>.+?)\s*(\s(?<caseSensitive>[iIsS]))?\s*)?\]/u,
  id: /#(?<name>[-\w\p{^ASCII}]+)/u,
  class: /\.(?<name>[-\w\p{^ASCII}]+)/u,
  comma: /\s*,\s*/u,
  combinator: /\s*[\s>+~]\s*/u,
  pseudo_element: /::(?<name>[-\w\p{^ASCII}]+)(?:\((?<argument>¶*)\))?/u,
  pseudo_class: /:(?<name>[-\w\p{^ASCII}]+)(?:\((?<argument>¶*)\))?/u,
  universal: /(?:(?<namespace>\*|[-\w\p{^ASCII}]*)\|)?\*/u,
  type: /(?:(?<namespace>\*|[-\w\p{^ASCII}]*)\|)?(?<name>[-\w\p{^ASCII}]+)/u
}.freeze
ARGUMENT_PATTERNS = 
{
  pseudo_element: Regexp.new(
    TOKENS[:pseudo_element].source.sub("(?<argument>¶*)", "(?<argument>.*)"),
    TOKENS[:pseudo_element].options
  ),
  pseudo_class: Regexp.new(
    TOKENS[:pseudo_class].source.sub("(?<argument>¶*)", "(?<argument>.*)"),
    TOKENS[:pseudo_class].options
  )
}.freeze
TRIM_TOKENS = 
Set.new(%i[combinator comma]).freeze
RECURSIVE_PSEUDO_CLASSES = 
Set.new(
  %w[not is where has matches -moz-any -webkit-any nth-child nth-last-child]
).freeze
NTH_CHILD_REGEXP = 
/(?<index>[\dn+-]+)\s+of\s+(?<subtree>.+)/u
RECURSIVE_PSEUDO_CLASSES_ARGS = 
{
  "nth-child" => NTH_CHILD_REGEXP,
  "nth-last-child" => NTH_CHILD_REGEXP
}.freeze
STRING_PATTERN = 
/(['"])([^\\\n]*?)\1/u
ESCAPE_PATTERN = 
/\\./u
NTH_CHILD_ITEMS = 
%w[nth-child nth-last-child].freeze

Class Method Summary collapse

Class Method Details

.flatten(node, parent = nil) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 254

def flatten(node, parent = nil, &)
  return enum_for(:flatten, node, parent) unless block_given?

  case node[:type]
  when :list
    node[:list].each { |child| flatten(child, node, &) }
  when :complex
    flatten(node[:left], node, &)
    flatten(node[:right], node, &)
  when :relative
    flatten(node[:right], node, &)
  when :compound
    node[:list].each { |token| yield(token, node) }
  else
    yield(node, parent)
  end
end

.get_argument_pattern_by_type(type) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 50

def get_argument_pattern_by_type(type)
  ARGUMENT_PATTERNS[type] || TOKENS[type]
end

.gobble_parens(text, offset) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 54

def gobble_parens(text, offset)
  nesting = 0
  result = +""
  while offset < text.length
    char = text[offset]
    case char
    when "("
      nesting += 1
    when ")"
      nesting -= 1
    end
    result << char
    offset += 1
    return result if nesting.zero?
  end
  result
end

.nest_tokens(tokens, list: true) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 199

def nest_tokens(tokens, list: true)
  if list && tokens.any? { |t| t[:type] == :comma }
    selectors = []
    temp = []

    tokens.each_with_index do |token, index|
      if token[:type] == :comma
        raise ArgumentError, "Incorrect comma at #{index}" if temp.empty?

        selectors << nest_tokens(temp, list: false)
        temp = []
      else
        temp << token
      end
    end

    raise ArgumentError, "Trailing comma" if temp.empty?

    selectors << nest_tokens(temp, list: false)
    return { type: :list, list: selectors }
  end

  (tokens.length - 1).downto(0) do |i|
    token = tokens[i]
    next unless token[:type] == :combinator

    left = tokens[0...i]
    right = tokens[(i + 1)..] || []

    if left.empty?
      return {
        type: :relative,
        combinator: token[:content],
        right: nest_tokens(right)
      }
    end

    return {
      type: :complex,
      combinator: token[:content],
      left: nest_tokens(left),
      right: nest_tokens(right)
    }
  end

  case tokens.length
  when 0
    raise ArgumentError, "Could not build AST."
  when 1
    tokens.first
  else
    { type: :compound, list: tokens.dup }
  end
end

.parse(selector, recursive: true, list: true) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 282

def parse(selector, recursive: true, list: true)
  tokens = tokenize(selector)
  return nil if tokens.empty?

  ast = nest_tokens(tokens, list: list)
  return ast unless recursive

  flatten(ast).each do |token, _|
    next unless token[:type] == :pseudo_class

    argument = token[:argument]
    next unless argument
    next unless RECURSIVE_PSEUDO_CLASSES.include?(token[:name])

    child_arg = RECURSIVE_PSEUDO_CLASSES_ARGS[token[:name]]
    if child_arg
      match = child_arg.match(argument)
      next unless match

      match.named_captures.each do |key, value|
        token[key.to_sym] = value
      end
      argument = match[:subtree]
    end

    next if argument.nil? || argument.empty?

    token[:subtree] = parse(argument, recursive: true, list: true)
  end

  ast
end

.specificity(selector) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 343

def specificity(selector)
  ast = selector
  ast = parse(selector, recursive: true) if selector.is_a?(String)
  return [] unless ast

  if ast.is_a?(Hash) && ast[:type] == :list
    base = 10
    specificities = ast[:list].map do |entry|
      sp = specificity(entry)
      base = [base, *sp].max
      sp
    end
    numbers = specificities.map { |sp| specificity_to_number(sp, base) }
    return specificities[numbers.index(numbers.max)]
  end

  ret = [0, 0, 0]
  flatten(ast).each do |token, _|
    case token[:type]
    when :id
      ret[0] += 1
    when :class, :attribute
      ret[1] += 1
    when :pseudo_element, :type
      ret[2] += 1
    when :pseudo_class
      next if token[:name] == "where"

      unless RECURSIVE_PSEUDO_CLASSES.include?(token[:name]) && token[:subtree]
        ret[1] += 1
        next
      end
      sub = specificity(token[:subtree])
      sub.each_with_index { |value, index| ret[index] += value }
      ret[1] += 1 if NTH_CHILD_ITEMS.include?(token[:name])
    end
  end

  ret
end

.specificity_to_number(specificity, base = nil) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 334

def specificity_to_number(specificity, base = nil)
  base ||= specificity.max.to_i + 1
  (specificity[0] * (base << 1)) +
    (specificity[1] * base) +
    specificity[2]
end

.stringify(list_or_node) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 315

def stringify(list_or_node)
  return list_or_node.map { |token| token[:content] }.join if list_or_node.is_a?(Array)

  case list_or_node[:type]
  when :list
    list_or_node[:list].map { |node| stringify(node) }.join(",")
  when :relative
    list_or_node[:combinator] + stringify(list_or_node[:right])
  when :complex
    stringify(list_or_node[:left]) +
      list_or_node[:combinator] +
      stringify(list_or_node[:right])
  when :compound
    list_or_node[:list].map { |node| stringify(node) }.join
  else
    list_or_node[:content]
  end
end

.tokenize(selector, grammar = TOKENS) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 129

def tokenize(selector, grammar = TOKENS)
  selector = selector.to_s.strip
  return [] if selector.empty?

  replacements = []

  selector = selector.gsub(ESCAPE_PATTERN) do |value|
    offset = Regexp.last_match.begin(0)
    replacements << { value: value, offset: offset }
    ESCAPE_SENTINEL * value.length
  end

  selector = selector.gsub(STRING_PATTERN) do |value|
    match = Regexp.last_match
    quote = match[1]
    content = match[2] || ""
    offset = match.begin(0)
    replacements << { value: value, offset: offset }
    "#{quote}#{STRING_SENTINEL * content.length}#{quote}"
  end

  pos = 0
  while (offset = selector.index("(", pos))
    value = gobble_parens(selector, offset)
    replacements << { value: value, offset: offset }
    placeholder = "(#{PLACEHOLDER_CHAR * (value.length - 2)})"
    selector = selector[0...offset] + placeholder + selector[(offset + value.length)..].to_s
    pos = offset + placeholder.length
  end

  tokens = tokenize_by(selector, grammar)
  changed_tokens = {}

  replacements.reverse_each do |replacement|
    tokens.each do |token|
      next unless token.is_a?(Hash)

      offset = replacement[:offset]
      value = replacement[:value]
      token_pos = token[:pos]
      next unless token_pos[0] <= offset && (offset + value.length) <= token_pos[1]

      content = token[:content]
      token_offset = offset - token_pos[0]
      token[:content] =
        content[0...token_offset].to_s +
        value +
        content[(token_offset + value.length)..].to_s
      changed_tokens[token.object_id] = token
    end
  end

  changed_tokens.each_value do |token|
    pattern = get_argument_pattern_by_type(token[:type])
    raise ArgumentError, "Unknown token type: #{token[:type]}" unless pattern

    match = pattern.match(token[:content])
    unless match
      raise ArgumentError,
            "Unable to parse content for #{token[:type]}: #{token[:content]}"
    end

    match.named_captures.each do |key, value|
      token[key.to_sym] = value if value
    end
  end

  tokens
end

.tokenize_by(text, grammar = TOKENS) ⇒ Object 



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# File 'lib/minicss/sel.rb', line 72

def tokenize_by(text, grammar = TOKENS)
  return [] if text.nil? || text.empty?

  tokens = [text.dup]

  grammar.each do |type, pattern|
    i = 0
    while i < tokens.length
      token = tokens[i]
      unless token.is_a?(String)
        i += 1
        next
      end

      match = pattern.match(token)
      if match.nil?
        i += 1
        next
      end

      content = match[0]
      start_index = match.begin(0)
      before = token[0...start_index]
      after = token[(start_index + content.length)..]
      parts = []

      parts << before if before && !before.empty?

      named = match.named_captures.transform_keys(&:to_sym).compact
      parts << named.merge(type: type, content: content)

      parts << after if after && !after.empty?

      tokens.slice!(i)
      tokens.insert(i, *parts)
    end
  end

  offset = 0
  tokens.each do |token|
    case token
    when String
      raise ArgumentError,
            "Unexpected sequence #{token} found at index #{offset}"
    when Hash
      offset += token[:content].length
      token[:pos] = [offset - token[:content].length, offset]
      if TRIM_TOKENS.include?(token[:type])
        trimmed = token[:content].strip
        token[:content] = trimmed.empty? ? " " : trimmed
      end
    end
  end

  tokens
end

.walk(node, visit = nil, parent = nil, &block) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/minicss/sel.rb', line 272

def walk(node, visit = nil, parent = nil, &block)
  visitor = visit || block
  raise ArgumentError, "No visitor provided" unless visitor
  return if node.nil?

  flatten(node, parent).each do |token, ast|
    visitor.call(token, ast)
  end
end