Compression Mapper and/or Serializer

[paneq]

I think Mapper would be more flexible.

Inspired by #294

module RubyEventStore
  module Mappers
    class CompressionMapper
      def initialize(inner_mapper:, compressor: )
        @inner = inner_mapper
        @compressor = compressor
      end

      def event_to_serialized_record(domain_event)
        s = inner_mapper.event_to_serialized_record(domain_event)
        s.data = compressor.compress(s.data)
        s.metadata = compressor.compress(s.metadata)
        s
      end

      def serialized_record_to_event(record)
        record.data = compressor.decompress(record.data)
        record.metadata = compressor.decompress(record.metadata)
        inner_mapper.serialized_record_to_event(record)
      end

      private

      attr_reader :inner, :compressor

    end
  end
end

potential name for passed compressor methods:

• deflate/inflate (zlib inspired)
• compress/uncompress
• compress/decompress
• pack/unpack

or take separately compressor and decompressor which respond to #call

[mostlyobvious]

That can now be event a smaller component, that is Transformation.