Type discriminator about msgpack-crystal HOT 2 CLOSED

    macro use_msgpack_discriminator(field, mapping)
      {% unless mapping.is_a?(HashLiteral) || mapping.is_a?(NamedTupleLiteral) %}
        {% mapping.raise "mapping argument must be a HashLiteral or a NamedTupleLiteral, not #{mapping.class_name.id}" %}
      {% end %}

      def self.new(pull : ::MessagePack::Unpacker)
        node = pull.read_node
        pull2 = MessagePack::NodeUnpacker.new(node)
        discriminator_value = nil
        pull2.consume_table do |key|
          if key == {{field.id.stringify}}
          case token = pull2.read_token
          when MessagePack::Token::IntT, MessagePack::Token::StringT, MessagePack::Token::BoolT
            discriminator_value = token.value
            break
          else
            # nothing more to do
            raise ::MessagePack::TypeCastError.new("Msgpack discriminator field '{{field.id}}' has an invalid value type of #{MessagePack::Token.to_s(token)}", token.byte_number)
          end
          else
            pull2.skip_value
          end
        end

        print(discriminator_value)

        unless discriminator_value
          raise ::MessagePack::UnpackError.new("Missing Msgpack discriminator field '{{field.id}}'", 0)
        end

        case discriminator_value
        {% for key, value in mapping %}
          {% if mapping.is_a?(NamedTupleLiteral) %}
            when {{key.id.stringify}}
          {% else %}
            {% if key.is_a?(StringLiteral) %}
              when {{key}}
            {% elsif key.is_a?(NumberLiteral) || key.is_a?(BoolLiteral) %}
              when {{key.id}}
            {% elsif key.is_a?(Path) %}
              when {{key.resolve}}
            {% else %}
              {% key.raise "mapping keys must be one of StringLiteral, NumberLiteral, BoolLiteral, or Path, not #{key.class_name.id}" %}
            {% end %}
          {% end %}
          {{value.id}}.new(MessagePack::NodeUnpacker.new(node))
        {% end %}
        else
          raise ::MessagePack::UnpackError.new("Unknown '{{field.id}}' discriminator value: #{discriminator_value.inspect}", 0)
        end
      end
    end