Skip to content
This repository
tag: v2.1.0
Fetching contributors…

Cannot retrieve contributors at this time

file 275 lines (255 sloc) 7.259 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275
module ActiveSupport
  # Callbacks are hooks into the lifecycle of an object that allow you to trigger logic
  # before or after an alteration of the object state.
  #
  # Mixing in this module allows you to define callbacks in your class.
  #
  # Example:
  # class Storage
  # include ActiveSupport::Callbacks
  #
  # define_callbacks :before_save, :after_save
  # end
  #
  # class ConfigStorage < Storage
  # before_save :saving_message
  # def saving_message
  # puts "saving..."
  # end
  #
  # after_save do |object|
  # puts "saved"
  # end
  #
  # def save
  # run_callbacks(:before_save)
  # puts "- save"
  # run_callbacks(:after_save)
  # end
  # end
  #
  # config = ConfigStorage.new
  # config.save
  #
  # Output:
  # saving...
  # - save
  # saved
  #
  # Callbacks from parent classes are inherited.
  #
  # Example:
  # class Storage
  # include ActiveSupport::Callbacks
  #
  # define_callbacks :before_save, :after_save
  #
  # before_save :prepare
  # def prepare
  # puts "preparing save"
  # end
  # end
  #
  # class ConfigStorage < Storage
  # before_save :saving_message
  # def saving_message
  # puts "saving..."
  # end
  #
  # after_save do |object|
  # puts "saved"
  # end
  #
  # def save
  # run_callbacks(:before_save)
  # puts "- save"
  # run_callbacks(:after_save)
  # end
  # end
  #
  # config = ConfigStorage.new
  # config.save
  #
  # Output:
  # preparing save
  # saving...
  # - save
  # saved
  module Callbacks
    class CallbackChain < Array
      def self.build(kind, *methods, &block)
        methods, options = extract_options(*methods, &block)
        methods.map! { |method| Callback.new(kind, method, options) }
        new(methods)
      end

      def run(object, options = {}, &terminator)
        enumerator = options[:enumerator] || :each

        unless block_given?
          send(enumerator) { |callback| callback.call(object) }
        else
          send(enumerator) do |callback|
            result = callback.call(object)
            break result if terminator.call(result, object)
          end
        end
      end

      def |(chain)
        if chain.is_a?(CallbackChain)
          chain.each { |callback| self | callback }
        else
          if (found_callback = find(chain)) && (index = index(chain))
            self[index] = chain
          else
            self << chain
          end
        end
        self
      end

      def find(callback, &block)
        select { |c| c == callback && (!block_given? || yield(c)) }.first
      end

      def delete(callback)
        super(callback.is_a?(Callback) ? callback : find(callback))
      end

      private
        def self.extract_options(*methods, &block)
          methods.flatten!
          options = methods.extract_options!
          methods << block if block_given?
          return methods, options
        end

        def extract_options(*methods, &block)
          self.class.extract_options(*methods, &block)
        end
    end

    class Callback
      attr_reader :kind, :method, :identifier, :options

      def initialize(kind, method, options = {})
        @kind = kind
        @method = method
        @identifier = options[:identifier]
        @options = options
      end

      def ==(other)
        case other
        when Callback
          (self.identifier && self.identifier == other.identifier) || self.method == other.method
        else
          (self.identifier && self.identifier == other) || self.method == other
        end
      end

      def eql?(other)
        self == other
      end

      def dup
        self.class.new(@kind, @method, @options.dup)
      end

      def call(*args, &block)
        evaluate_method(method, *args, &block) if should_run_callback?(*args)
      rescue LocalJumpError
        raise ArgumentError,
          "Cannot yield from a Proc type filter. The Proc must take two " +
          "arguments and execute #call on the second argument."
      end

      private
        def evaluate_method(method, *args, &block)
          case method
            when Symbol
              object = args.shift
              object.send(method, *args, &block)
            when String
              eval(method, args.first.instance_eval { binding })
            when Proc, Method
              method.call(*args, &block)
            else
              if method.respond_to?(kind)
                method.send(kind, *args, &block)
              else
                raise ArgumentError,
                  "Callbacks must be a symbol denoting the method to call, a string to be evaluated, " +
                  "a block to be invoked, or an object responding to the callback method."
              end
            end
        end

        def should_run_callback?(*args)
          if options[:if]
            evaluate_method(options[:if], *args)
          elsif options[:unless]
            !evaluate_method(options[:unless], *args)
          else
            true
          end
        end
    end

    def self.included(base)
      base.extend ClassMethods
    end

    module ClassMethods
      def define_callbacks(*callbacks)
        callbacks.each do |callback|
          class_eval <<-"end_eval"
def self.#{callback}(*methods, &block)
callbacks = CallbackChain.build(:#{callback}, *methods, &block)
(@#{callback}_callbacks ||= CallbackChain.new).concat callbacks
end

def self.#{callback}_callback_chain
@#{callback}_callbacks ||= CallbackChain.new

if superclass.respond_to?(:#{callback}_callback_chain)
CallbackChain.new(superclass.#{callback}_callback_chain + @#{callback}_callbacks)
else
@#{callback}_callbacks
end
end
end_eval
        end
      end
    end

    # Runs all the callbacks defined for the given options.
    #
    # If a block is given it will be called after each callback receiving as arguments:
    #
    # * the result from the callback
    # * the object which has the callback
    #
    # If the result from the block evaluates to false, the callback chain is stopped.
    #
    # Example:
    # class Storage
    # include ActiveSupport::Callbacks
    #
    # define_callbacks :before_save, :after_save
    # end
    #
    # class ConfigStorage < Storage
    # before_save :pass
    # before_save :pass
    # before_save :stop
    # before_save :pass
    #
    # def pass
    # puts "pass"
    # end
    #
    # def stop
    # puts "stop"
    # return false
    # end
    #
    # def save
    # result = run_callbacks(:before_save) { |result, object| result == false }
    # puts "- save" if result
    # end
    # end
    #
    # config = ConfigStorage.new
    # config.save
    #
    # Output:
    # pass
    # pass
    # stop
    def run_callbacks(kind, options = {}, &block)
      self.class.send("#{kind}_callback_chain").run(self, options, &block)
    end
  end
end
Something went wrong with that request. Please try again.