Method: Memoist#memoize

Defined in:

lib/memoist.rb

#memoize(*method_names) ⇒ Object

# File 'lib/memoist.rb', line 114

def memoize(*method_names)
  if method_names.last.is_a?(Hash)
    identifier = method_names.pop[:identifier]
  end

  Memoist.memoist_eval(self) do
    unless singleton_class.method_defined?(:memoized_methods)
      def self.memoized_methods
        @_memoized_methods ||= []
      end
    end
  end

  method_names.each do |method_name|
    unmemoized_method = Memoist.unmemoized_method_for(method_name, identifier)
    memoized_ivar = Memoist.memoized_ivar_for(method_name, identifier)

    Memoist.memoist_eval(self) do
      include InstanceMethods

      if method_defined?(unmemoized_method)
        warn "Already memoized #{method_name}"
        return
      end
      alias_method unmemoized_method, method_name

      mm = MemoizedMethod.new(method_name, memoized_ivar, instance_method(method_name).arity)
      self.memoized_methods << mm
      if mm.arity == 0

        # define a method like this;

        # def mime_type(reload=true)
        #   skip_cache = reload || !instance_variable_defined?("@_memoized_mime_type")
        #   set_cache = skip_cache && !frozen?
        #
        #   if skip_cache
        #     value = _unmemoized_mime_type
        #   else
        #     value = @_memoized_mime_type
        #   end
        #
        #   if set_cache
        #     @_memoized_mime_type = value
        #   end
        #
        #   value
        # end

        module_eval <<-EOS, __FILE__, __LINE__ + 1
          def #{method_name}(reload = false)
            skip_cache = reload || !instance_variable_defined?("#{memoized_ivar}")
            set_cache = skip_cache && !frozen?

            if skip_cache
              value = #{unmemoized_method}
            else
              value = #{memoized_ivar}
            end

            if set_cache
              #{memoized_ivar} = value
            end

            value
          end
        EOS
      else

        # define a method like this;

        # def mime_type(*args)
        #   reload = Memoist.extract_reload!(method(:_unmemoized_mime_type), args)
        #
        #   skip_cache = reload || !memoized_with_args?(:mime_type, args)
        #   set_cache = skip_cache && !frozen
        #
        #   if skip_cache
        #     value = _unmemoized_mime_type(*args)
        #   else
        #     value = @_memoized_mime_type[args]
        #   end
        #
        #   if set_cache
        #     @_memoized_mime_type ||= {}
        #     @_memoized_mime_type[args] = value
        #   end
        #
        #   value
        # end

        module_eval <<-EOS, __FILE__, __LINE__ + 1
          def #{method_name}(*args)
            reload = Memoist.extract_reload!(method(#{unmemoized_method.inspect}), args)

            skip_cache = reload || !(instance_variable_defined?(#{memoized_ivar.inspect}) && #{memoized_ivar} && #{memoized_ivar}.has_key?(args))
            set_cache = skip_cache && !frozen?

            if skip_cache
              value = #{unmemoized_method}(*args)
            else
              value = #{memoized_ivar}[args]
            end

            if set_cache
              #{memoized_ivar} ||= {}
              #{memoized_ivar}[args] = value
            end

            value
          end
        EOS
      end

      if private_method_defined?(unmemoized_method)
        private method_name
      elsif protected_method_defined?(unmemoized_method)
        protected method_name
      end
    end
  end
  # return a chainable method_name symbol if we can
  method_names.length == 1 ? method_names.first : method_names
end