cache.rb

require 'pry'
class Cache
	attr_reader :value
	attr_reader :version
	attr_reader :versions

	# we are storing values as Ruby hash values
	def initialize(value = {}, version = 0, versions = [])
		@value = value
		@version = version
		@versions = versions
	end

	def put(k, v)
		# snapshot before we change any data
		@versions << Cache.new(@value, @version)

		# we assume new values are strings and convert to symbols, for easier get/setting.
		new_value = {k.to_sym => v}
		@value = @value.merge(new_value)
		@version += 1

		puts "PUT(##{@version}) #{k} = #{v}"
	end

	def get(k, version = nil)
		if !version.nil? && version < @versions.size - 1
			value = @versions[version].value
		else
			value = @value
		end

		if value[k.to_sym].nil?
			puts "GET #{k} = <NULL>"
		else
			puts "GET #{k} = #{value[k.to_sym]}"
		end
	end
end