class Racc::Rule

def ==(other)
  other.kind_of?(Rule) and @ident == other.ident
end

def [](idx)
  @symbols[idx]
end

def accept?
  if tok = @symbols[-1]
    tok.anchor?
  else
    false
  end
end

def each(&block)
  @symbols.each(&block)
end

def each_rule(&block)
  yield self
  @alternatives.each(&block)
end

def empty?
  @symbols.empty?
end

def hash=(n)
  @hash = n
  ptrs = []
  @symbols.each_with_index do |sym, idx|
    ptrs.push LocationPointer.new(self, idx, sym)
  end
  ptrs.push LocationPointer.new(self, @symbols.size, nil)
  @ptrs = ptrs
end

def initialize(target, syms, act)
  @target = target
  @symbols = syms
  @action = act
  @alternatives = []
  @ident = nil
  @hash = nil
  @ptrs = nil
  @precedence = nil
  @specified_prec = nil
  @null = nil
  @useless = nil
end

def inspect
  "#<Racc::Rule id=#{@ident} (#{@target})>"
end

def null=(n)    @null = n end

def nullable?() @null end

def prec(sym, &block)
  @specified_prec = sym
  if block
    unless @action.empty?
      raise CompileError, 'both of rule action block and prec block given'
    end
    @action = UserAction.proc(block)
  end
  self
end

def precedence
  @specified_prec || @precedence
end

def precedence=(sym)
  @precedence ||= sym
end

def replace(src, dest)
  @target = dest
  @symbols = @symbols.map {|s| s == src ? dest : s }
end

def rule
  self
end

def size
  @symbols.size
end

def to_s
  "#<rule#{@ident}>"
end

def useless=(u) @useless = u end

def useless?()  @useless end

def |(x)
  @alternatives.push x.rule
  self
end