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module ActiveSupport
module Callbacks
class Callback
def self.run(callbacks, object, options = {}, &terminator)
enumerator = options[:enumerator] || :each
unless block_given?
callbacks.send(enumerator) { |callback| callback.call(object) }
else
callbacks.send(enumerator) do |callback|
result = callback.call(object)
break result if terminator.call(result, object)
end
end
end
attr_reader :kind, :method, :identifier, :options
def initialize(kind, method, options = {})
@kind = kind
@method = method
@identifier = options[:identifier]
@options = options
end
def call(object)
evaluate_method(method, object) if should_run_callback?(object)
end
private
def evaluate_method(method, object)
case method
when Symbol
object.send(method)
when String
eval(method, object.instance_eval { binding })
when Proc, Method
method.call(object)
else
if method.respond_to?(kind)
method.send(kind, object)
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?(object)
if options[:if]
evaluate_method(options[:if], object)
elsif options[:unless]
!evaluate_method(options[:unless], object)
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)
options = methods.extract_options!
methods << block if block_given?
callbacks = methods.map { |method| Callback.new(:#{callback}, method, options) }
(@#{callback}_callbacks ||= []).concat callbacks
end
def self.#{callback}_callback_chain
@#{callback}_callbacks ||= []
if superclass.respond_to?(:#{callback}_callback_chain)
superclass.#{callback}_callback_chain + @#{callback}_callbacks
else
@#{callback}_callbacks
end
end
end_eval
end
end
end
def run_callbacks(kind, options = {}, &block)
Callback.run(self.class.send("#{kind}_callback_chain"), self, options, &block)
end
end
end
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