class Sass::Selector::CommaSequence

def _eql?(other)
  other.class == self.class && other.members.eql?(members)
end

def _hash
  members.hash
end

def contains_parent_ref?
  @members.any? {|sel| sel.contains_parent_ref?}
end

def do_extend(extends, parent_directives = [], replace = false, seen = Set.new,
    original = true)
  CommaSequence.new(members.map do |seq|
    seq.do_extend(extends, parent_directives, replace, seen, original)
  end.flatten)
end

def initialize(seqs)
  @members = seqs
end

def inspect
  members.map {|m| m.inspect}.join(", ")
end

def populate_extends(extends, extendee, extend_node = nil, parent_directives = [],
    allow_compound_target = false)
  extendee.members.each do |seq|
    if seq.members.size > 1
      raise Sass::SyntaxError.new("Can't extend #{seq}: can't extend nested selectors")
    end
    sseq = seq.members.first
    if !sseq.is_a?(Sass::Selector::SimpleSequence)
      raise Sass::SyntaxError.new("Can't extend #{seq}: invalid selector")
    elsif sseq.members.any? {|ss| ss.is_a?(Sass::Selector::Parent)}
      raise Sass::SyntaxError.new("Can't extend #{seq}: can't extend parent selectors")
    end
    sel = sseq.members
    if !allow_compound_target && sel.length > 1
      @@compound_extend_deprecation.warn(sseq.filename, sseq.line, <<WARNING)
ing a compound selector, #{sseq}, is deprecated and will not be supported in a future release.
er "@extend #{sseq.members.join(', ')}" instead.
tp://bit.ly/ExtendCompound for details.
G
    end
    members.each do |member|
      unless member.members.last.is_a?(Sass::Selector::SimpleSequence)
        raise Sass::SyntaxError.new("#{member} can't extend: invalid selector")
      end
      extends[sel] = Sass::Tree::Visitors::Cssize::Extend.new(
        member, sel, extend_node, parent_directives, false)
    end
  end
end

def resolve_parent_refs(super_cseq, implicit_parent = true)
  if super_cseq.nil?
    if contains_parent_ref?
      raise Sass::SyntaxError.new(
        "Base-level rules cannot contain the parent-selector-referencing character '&'.")
    end
    return self
  end
  CommaSequence.new(Sass::Util.flatten_vertically(@members.map do |seq|
    seq.resolve_parent_refs(super_cseq, implicit_parent).members
  end))
end

def superselector?(cseq)
  cseq.members.all? {|seq1| members.any? {|seq2| seq2.superselector?(seq1)}}
end

def to_s(opts = {})
  @members.map do |m|
    next if opts[:placeholder] == false && m.invisible?
    m.to_s(opts)
  end.compact.
    join(opts[:style] == :compressed ? "," : ", ").
    gsub(", \n", ",\n")
end

def to_sass_script
  Sass::Script::Value::List.new(members.map do |seq|
    Sass::Script::Value::List.new(seq.members.map do |component|
      next if component == "\n"
      Sass::Script::Value::String.new(component.to_s)
    end.compact, separator: :space)
  end, separator: :comma)
end

def unify(other)
  results = members.map {|seq1| other.members.map {|seq2| seq1.unify(seq2)}}.flatten.compact
  results.empty? ? nil : CommaSequence.new(results.map {|cseq| cseq.members}.flatten)
end