class Racc::Sym

def dummy?
  @dummyp
end

def initialize(value, dummyp)
  @ident = nil
  @value = value
  @dummyp = dummyp
  @term  = nil
  @nterm = nil
  @should_terminal = false
  @precedence = nil
  case value
  when Symbol
    @to_s = value.to_s
    @serialized = value.inspect
    @string = false
  when String
    @to_s = value.inspect
    @serialized = value.dump
    @string = true
  when false
    @to_s = '$end'
    @serialized = 'false'
    @string = false
  when ErrorSymbolValue
    @to_s = 'error'
    @serialized = 'Object.new'
    @string = false
  else
    raise ArgumentError, "unknown symbol value: #{value.class}"
  end
  @heads    = []
  @locate   = []
  @snull    = nil
  @null     = nil
  @expand   = nil
  @useless  = nil
end

def nonterminal?
  @nterm
end

def null=(n)
  @null = n
end

def nullable?
  @null
end

def once_writer(nm)
  nm = nm.id2name
  module_eval(<<-EOS)
    def #{nm}=(v)
      raise 'racc: fatal: @#{nm} != nil' unless @#{nm}.nil?
      @#{nm} = v
    end
  EOS
end

def rule
  Rule.new(nil, [self], UserAction.empty)
end

def self_null?
  @snull
end

def serialize
  @serialized
end

def should_terminal
  @should_terminal = true
end

def should_terminal?
  @should_terminal
end

def string_symbol?
  @string
end

def term=(t)
  raise 'racc: fatal: term= called twice' unless @term.nil?
  @term = t
  @nterm = !t
end

def terminal?
  @term
end

def to_s
  @to_s.dup
end

def useless=(f)
  @useless = f
end

def useless?
  @useless
end

def |(x)
  rule() | x.rule
end