Contents

module Parser

  class Lexer::StackState
    def initialize(name)
      @name  = name.freeze
      @stack = 0
    end

    def push(bit)
      bit_value = bit ? 1 : 0
      @stack = (@stack << 1) | bit_value

      bit
    end

    def pop
      bit_value = @stack & 1
      @stack  >>= 1

      bit_value == 1
    end

    def lexpop
      push(pop || pop)
    end

    def active?
      @stack[0] == 1
    end

    def to_s
      "[#{@stack.to_s(2)} <= #{@name}]"
    end

    alias inspect to_s
  end

end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
parser-0.9.1	lib/parser/lexer/stack_state.rb
parser-0.9.0	lib/parser/lexer/stack_state.rb