require 'antlr4/runtime/prediction_context'
require 'antlr4/runtime/prediction_context_utils'

module Antlr4::Runtime

  class SingletonPredictionContext < PredictionContext
    attr_accessor :parent
    attr_accessor :return_state

    def initialize(parent, return_state)
      super(!parent.nil? ? PredictionContextUtils.calculate_hash_code1(parent, return_state) : PredictionContextUtils.calculate_empty_hash_code)
      @parent = parent
      @return_state = return_state
    end

    def get_parent(_i)
      @parent
    end

    def size
      1
    end

    def empty?
      @return_state == EMPTY_RETURN_STATE
    end

    def get_return_state(_index)
      @return_state
    end

    def equals(other)
      if self == other
        return true
      elsif !(other.is_a? SingletonPredictionContext)
        return false
      end

      if hash != other.hash
        return false # can't be same if hash is different
      end

      @return_state == other.return_state && (!@parent.nil? && @parent.eql?(other.parent))
    end

    def to_s
      up = !@parent.nil? ? @parent.to_s : ''
      if up.empty?
        return '$' if @return_state == EMPTY_RETURN_STATE

        return @return_state.to_s
      end
      @return_state.to_s + ' ' + up
    end
  end
end