class Regexp::Expression::CharacterSet

def <<(member)
  if @members.last.is_a?(CharacterSubSet) and not @members.last.closed?
    @members.last << member
  else
    @members << member
  end
end

def clone
  copy = super
  copy.members = @members.map {|m| m.clone }
  copy
end

def close
  if @members.last.is_a?(CharacterSubSet) and not @members.last.closed?
    @members.last.close
  else
    @closed = true
  end
end

def closed?
  @closed
end

def each(&block)
  @members.each {|m| yield m}
end

def each_with_index(&block)
  @members.each_with_index {|m, i| yield m, i}
end

def include?(member, directly = false)
  @members.each do |m|
    if m.is_a?(CharacterSubSet) and not directly
      return true if m.include?(member)
    else
      return true if member == m.to_s
    end
  end; false
end

def initialize(token)
  @members  = []
  @negative = false
  @closed   = false
  super
end

def length
  @members.length
end

def matches?(input)
  input =~ /#{to_s}/ ? true : false
end

def negate
  if @members.last.is_a?(CharacterSubSet)
    @members.last.negate
  else
    @negative = true
  end
end

def negative?
  @negative
end

def to_s(format = :full)
  s = ''
  s << @text.dup
  s << '^' if negative?
  s << @members.join
  s << ']'
  case format
  when :base
  else
    s << @quantifier.to_s if quantified?
  end
  s
end