module Yammer
  class IdentityMap

    class InvalidKeyError < StandardError; end

    def initialize
      @map  = {}
      @size = 0
    end

    # @note retrives key from identity map
    # @return [Hash]
    # @param key [string] 
    # @param default [Hash]
    def get(key, default=nil)
      @map["#{key}"] || default
    end

    # @note inserts a hash of attributes into identity map
    # @return [Hash]
    # @param key [string] 
    # @param value [Hash]
    def put(key, value)
      if key.nil? || key.empty?
        raise InvalidKeyError.new
      end
      @map["#{key}"] = value
    end

    # @note returns the current size of identity map
    # @return [Integer]
    def size
      @map.keys.count
    end

    # clears the entire identity map
    # @return [Hash]
    def purge!
      @map = {}
    end
  end
end