module Guff
  class TemplateToken
    getter :type
    getter :value

    TOKEN_TYPES = %i{key val}

    def initialize(@type : Symbol, @value : String)
      raise "invalid type: %s" % [@type] unless TOKEN_TYPES.includes?(@type)
    end

    def get(args : Hash(String, String))
      case @type
      when :key
        raise "missing key: %s" % [@value] unless args.has_key?(@value)
        args[@value]
      when :val
        @value
      else
        # never reached
        raise "unknown token type: %s" % [@type]
      end
    end
  end
end