1  module ActiveSupport
   2    module Memoizable
   3      def self.memoized_ivar_for(symbol)
   4        "@_memoized_#{symbol.to_s.sub(/\?\Z/, '_query').sub(/!\Z/, '_bang')}".to_sym
   5      end
   6 
   7      module InstanceMethods
   8        def self.included(base)
   9          base.class_eval do
  10            unless base.method_defined?(:freeze_without_memoizable)
  11              alias_method_chain :freeze, :memoizable
  12            end
  13          end
  14        end
  15 
  16        def freeze_with_memoizable
  17          memoize_all unless frozen?
  18          freeze_without_memoizable
  19        end
  20 
  21        def memoize_all
  22          prime_cache ".*"
  23        end
  24 
  25        def unmemoize_all
  26          flush_cache ".*"
  27        end
  28 
  29        def prime_cache(*syms)
  30          syms.each do |sym|
  31            methods.each do |m|
  32              if m.to_s =~ /^_unmemoized_(#{sym})/
  33                if method(m).arity == 0
  34                  __send__($1)
  35                else
  36                  ivar = ActiveSupport::Memoizable.memoized_ivar_for($1)
  37                  instance_variable_set(ivar, {})
  38                end
  39              end
  40            end
  41          end
  42        end
  43 
  44        def flush_cache(*syms, &block)
  45          syms.each do |sym|
  46            (methods + private_methods + protected_methods).each do |m|
  47              if m.to_s =~ /^_unmemoized_(#{sym})/
  48                ivar = ActiveSupport::Memoizable.memoized_ivar_for($1)
  49                instance_variable_get(ivar).clear if instance_variable_defined?(ivar)
  50              end
  51            end
  52          end
  53        end
  54      end
  55 
  56      def memoize(*symbols)
  57        symbols.each do |symbol|
  58          original_method = :"_unmemoized_#{symbol}"
  59          memoized_ivar = ActiveSupport::Memoizable.memoized_ivar_for(symbol)
  60 
  61          class_eval <<-EOS, __FILE__, __LINE__ + 1
  62            include InstanceMethods                                                  # include InstanceMethods
  63                                                                                     #
  64            if method_defined?(:#{original_method})                                  # if method_defined?(:_unmemoized_mime_type)
  65              raise "Already memoized #{symbol}"                                     #   raise "Already memoized mime_type"
  66            end                                                                      # end
  67            alias #{original_method} #{symbol}                                       # alias _unmemoized_mime_type mime_type
  68                                                                                     #
  69            if instance_method(:#{symbol}).arity == 0                                # if instance_method(:mime_type).arity == 0
  70              def #{symbol}(reload = false)                                          #   def mime_type(reload = false)
  71                if reload || !defined?(#{memoized_ivar}) || #{memoized_ivar}.empty?  #     if reload || !defined?(@_memoized_mime_type) || @_memoized_mime_type.empty?
  72                  #{memoized_ivar} = [#{original_method}.freeze]                     #       @_memoized_mime_type = [_unmemoized_mime_type.freeze]
  73                end                                                                  #     end
  74                #{memoized_ivar}[0]                                                  #     @_memoized_mime_type[0]
  75              end                                                                    #   end
  76            else                                                                     # else
  77              def #{symbol}(*args)                                                   #   def mime_type(*args)
  78                #{memoized_ivar} ||= {} unless frozen?                               #     @_memoized_mime_type ||= {} unless frozen?
  79                reload = args.pop if args.last == true || args.last == :reload       #     reload = args.pop if args.last == true || args.last == :reload
  80                                                                                     #
  81                if defined?(#{memoized_ivar}) && #{memoized_ivar}                    #     if defined?(@_memoized_mime_type) && @_memoized_mime_type
  82                  if !reload && #{memoized_ivar}.has_key?(args)                      #       if !reload && @_memoized_mime_type.has_key?(args)
  83                    #{memoized_ivar}[args]                                           #         @_memoized_mime_type[args]
  84                  elsif #{memoized_ivar}                                             #       elsif @_memoized_mime_type
  85                    #{memoized_ivar}[args] = #{original_method}(*args).freeze        #         @_memoized_mime_type[args] = _unmemoized_mime_type(*args).freeze
  86                  end                                                                #       end
  87                else                                                                 #     else
  88                  #{original_method}(*args)                                          #       _unmemoized_mime_type(*args)
  89                end                                                                  #     end
  90              end                                                                    #   end
  91            end                                                                      # end
  92                                                                                     #
  93            if private_method_defined?(#{original_method.inspect})                   # if private_method_defined?(:_unmemoized_mime_type)
  94              private #{symbol.inspect}                                              #   private :mime_type
  95            elsif protected_method_defined?(#{original_method.inspect})              # elsif protected_method_defined?(:_unmemoized_mime_type)
  96              protected #{symbol.inspect}                                            #   protected :mime_type
  97            end                                                                      # end
  98          EOS
  99        end
 100      end
 101    end
 102  end