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tag: v3.0.9
602 lines (537 sloc) 19.25 kb
require 'active_support/concern'
require 'active_support/descendants_tracker'
require 'active_support/core_ext/array/wrap'
require 'active_support/core_ext/class/inheritable_attributes'
require 'active_support/core_ext/kernel/reporting'
require 'active_support/core_ext/kernel/singleton_class'
module ActiveSupport
# Callbacks are hooks into the life cycle 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 :save
# end
#
# class ConfigStorage < Storage
# set_callback :save, :before, :saving_message
# def saving_message
# puts "saving..."
# end
#
# set_callback :save, :after do |object|
# puts "saved"
# end
#
# def save
# run_callbacks :save do
# puts "- save"
# end
# 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 :save
#
# set_callback :save, :before, :prepare
# def prepare
# puts "preparing save"
# end
# end
#
# class ConfigStorage < Storage
# set_callback :save, :before, :saving_message
# def saving_message
# puts "saving..."
# end
#
# set_callback :save, :after do |object|
# puts "saved"
# end
#
# def save
# run_callbacks :save do
# puts "- save"
# end
# end
# end
#
# config = ConfigStorage.new
# config.save
#
# Output:
# preparing save
# saving...
# - save
# saved
#
module Callbacks
extend Concern
included do
extend ActiveSupport::DescendantsTracker
end
def run_callbacks(kind, *args, &block)
send("_run_#{kind}_callbacks", *args, &block)
end
def callback(kind)
ActiveSupport::Deprecation.warn("callback is deprecated. Please use run_callbacks")
send("_run_#{kind}_callbacks")
end
class Callback
@@_callback_sequence = 0
attr_accessor :chain, :filter, :kind, :options, :per_key, :klass, :raw_filter
def initialize(chain, filter, kind, options, klass)
@chain, @kind, @klass = chain, kind, klass
normalize_options!(options)
@per_key = options.delete(:per_key)
@raw_filter, @options = filter, options
@filter = _compile_filter(filter)
@compiled_options = _compile_options(options)
@callback_id = next_id
_compile_per_key_options
end
def clone(chain, klass)
obj = super()
obj.chain = chain
obj.klass = klass
obj.per_key = @per_key.dup
obj.options = @options.dup
obj.per_key[:if] = @per_key[:if].dup
obj.per_key[:unless] = @per_key[:unless].dup
obj.options[:if] = @options[:if].dup
obj.options[:unless] = @options[:unless].dup
obj
end
def normalize_options!(options)
options[:if] = Array.wrap(options[:if])
options[:unless] = Array.wrap(options[:unless])
options[:per_key] ||= {}
options[:per_key][:if] = Array.wrap(options[:per_key][:if])
options[:per_key][:unless] = Array.wrap(options[:per_key][:unless])
end
def name
chain.name
end
def next_id
@@_callback_sequence += 1
end
def matches?(_kind, _filter)
@kind == _kind && @filter == _filter
end
def _update_filter(filter_options, new_options)
filter_options[:if].push(new_options[:unless]) if new_options.key?(:unless)
filter_options[:unless].push(new_options[:if]) if new_options.key?(:if)
end
def recompile!(_options, _per_key)
_update_filter(self.options, _options)
_update_filter(self.per_key, _per_key)
@callback_id = next_id
@filter = _compile_filter(@raw_filter)
@compiled_options = _compile_options(@options)
_compile_per_key_options
end
def _compile_per_key_options
key_options = _compile_options(@per_key)
@klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def _one_time_conditions_valid_#{@callback_id}?
true #{key_options[0]}
end
RUBY_EVAL
end
# This will supply contents for before and around filters, and no
# contents for after filters (for the forward pass).
def start(key=nil, object=nil)
return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
# options[0] is the compiled form of supplied conditions
# options[1] is the "end" for the conditional
#
if @kind == :before || @kind == :around
if @kind == :before
# if condition # before_save :filter_name, :if => :condition
# filter_name
# end
filter = <<-RUBY_EVAL
unless halted
result = #{@filter}
halted = (#{chain.config[:terminator]})
end
RUBY_EVAL
[@compiled_options[0], filter, @compiled_options[1]].compact.join("\n")
else
# Compile around filters with conditions into proxy methods
# that contain the conditions.
#
# For `around_save :filter_name, :if => :condition':
#
# def _conditional_callback_save_17
# if condition
# filter_name do
# yield self
# end
# else
# yield self
# end
# end
#
name = "_conditional_callback_#{@kind}_#{next_id}"
@klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{name}(halted)
#{@compiled_options[0] || "if true"} && !halted
#{@filter} do
yield self
end
else
yield self
end
end
RUBY_EVAL
"#{name}(halted) do"
end
end
end
# This will supply contents for around and after filters, but not
# before filters (for the backward pass).
def end(key=nil, object=nil)
return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
if @kind == :around || @kind == :after
# if condition # after_save :filter_name, :if => :condition
# filter_name
# end
if @kind == :after
[@compiled_options[0], @filter, @compiled_options[1]].compact.join("\n")
else
"end"
end
end
end
private
# Options support the same options as filters themselves (and support
# symbols, string, procs, and objects), so compile a conditional
# expression based on the options
def _compile_options(options)
return [] if options[:if].empty? && options[:unless].empty?
conditions = []
unless options[:if].empty?
conditions << Array.wrap(_compile_filter(options[:if]))
end
unless options[:unless].empty?
conditions << Array.wrap(_compile_filter(options[:unless])).map {|f| "!#{f}"}
end
["if #{conditions.flatten.join(" && ")}", "end"]
end
# Filters support:
#
# Arrays:: Used in conditions. This is used to specify
# multiple conditions. Used internally to
# merge conditions from skip_* filters
# Symbols:: A method to call
# Strings:: Some content to evaluate
# Procs:: A proc to call with the object
# Objects:: An object with a before_foo method on it to call
#
# All of these objects are compiled into methods and handled
# the same after this point:
#
# Arrays:: Merged together into a single filter
# Symbols:: Already methods
# Strings:: class_eval'ed into methods
# Procs:: define_method'ed into methods
# Objects::
# a method is created that calls the before_foo method
# on the object.
#
def _compile_filter(filter)
method_name = "_callback_#{@kind}_#{next_id}"
case filter
when Array
filter.map {|f| _compile_filter(f)}
when Symbol
filter
when String
"(#{filter})"
when Proc
@klass.send(:define_method, method_name, &filter)
return method_name if filter.arity <= 0
method_name << (filter.arity == 1 ? "(self)" : " self, Proc.new ")
else
@klass.send(:define_method, "#{method_name}_object") { filter }
_normalize_legacy_filter(kind, filter)
scopes = Array.wrap(chain.config[:scope])
method_to_call = scopes.map{ |s| s.is_a?(Symbol) ? send(s) : s }.join("_")
@klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{method_name}(&blk)
#{method_name}_object.send(:#{method_to_call}, self, &blk)
end
RUBY_EVAL
method_name
end
end
def _normalize_legacy_filter(kind, filter)
if !filter.respond_to?(kind) && filter.respond_to?(:filter)
filter.singleton_class.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{kind}(context, &block) filter(context, &block) end
RUBY_EVAL
elsif filter.respond_to?(:before) && filter.respond_to?(:after) && kind == :around
def filter.around(context)
should_continue = before(context)
yield if should_continue
after(context)
end
end
end
end
# An Array with a compile method
class CallbackChain < Array
attr_reader :name, :config
def initialize(name, config)
@name = name
@config = {
:terminator => "false",
:rescuable => false,
:scope => [ :kind ]
}.merge(config)
end
def compile(key=nil, object=nil)
method = []
method << "value = nil"
method << "halted = false"
each do |callback|
method << callback.start(key, object)
end
if config[:rescuable]
method << "rescued_error = nil"
method << "begin"
end
method << "value = yield if block_given? && !halted"
if config[:rescuable]
method << "rescue Exception => e"
method << "rescued_error = e"
method << "end"
end
reverse_each do |callback|
method << callback.end(key, object)
end
method << "raise rescued_error if rescued_error" if config[:rescuable]
method << "halted ? false : (block_given? ? value : true)"
method.compact.join("\n")
end
end
module ClassMethods
# Make the run_callbacks :save method. The generated method takes
# a block that it'll yield to. It'll call the before and around filters
# in order, yield the block, and then run the after filters.
#
# run_callbacks :save do
# save
# end
#
# The run_callbacks :save method can optionally take a key, which
# will be used to compile an optimized callback method for each
# key. See #define_callbacks for more information.
#
def __define_runner(symbol) #:nodoc:
body = send("_#{symbol}_callbacks").compile(nil)
silence_warnings do
undef_method "_run_#{symbol}_callbacks" if method_defined?("_run_#{symbol}_callbacks")
class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def _run_#{symbol}_callbacks(key = nil, &blk)
if key
name = "_run__\#{self.class.name.hash.abs}__#{symbol}__\#{key.hash.abs}__callbacks"
unless respond_to?(name)
self.class.__create_keyed_callback(name, :#{symbol}, self, &blk)
end
send(name, &blk)
else
#{body}
end
end
private :_run_#{symbol}_callbacks
RUBY_EVAL
end
end
# This is called the first time a callback is called with a particular
# key. It creates a new callback method for the key, calculating
# which callbacks can be omitted because of per_key conditions.
#
def __create_keyed_callback(name, kind, object, &blk) #:nodoc:
@_keyed_callbacks ||= {}
@_keyed_callbacks[name] ||= begin
str = send("_#{kind}_callbacks").compile(name, object)
class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
def #{name}() #{str} end
protected :#{name}
RUBY_EVAL
true
end
end
# This is used internally to append, prepend and skip callbacks to the
# CallbackChain.
#
def __update_callbacks(name, filters = [], block = nil) #:nodoc:
type = [:before, :after, :around].include?(filters.first) ? filters.shift : :before
options = filters.last.is_a?(Hash) ? filters.pop : {}
filters.unshift(block) if block
([self] + ActiveSupport::DescendantsTracker.descendants(self)).each do |target|
chain = target.send("_#{name}_callbacks")
yield chain, type, filters, options
target.__define_runner(name)
end
end
# Set callbacks for a previously defined callback.
#
# Syntax:
# set_callback :save, :before, :before_meth
# set_callback :save, :after, :after_meth, :if => :condition
# set_callback :save, :around, lambda { |r| stuff; yield; stuff }
#
# Use skip_callback to skip any defined one.
#
# When creating or skipping callbacks, you can specify conditions that
# are always the same for a given key. For instance, in Action Pack,
# we convert :only and :except conditions into per-key conditions.
#
# before_filter :authenticate, :except => "index"
#
# becomes
#
# dispatch_callback :before, :authenticate, :per_key => {:unless => proc {|c| c.action_name == "index"}}
#
# Per-Key conditions are evaluated only once per use of a given key.
# In the case of the above example, you would do:
#
# run_callbacks(:dispatch, action_name) { ... dispatch stuff ... }
#
# In that case, each action_name would get its own compiled callback
# method that took into consideration the per_key conditions. This
# is a speed improvement for ActionPack.
#
def set_callback(name, *filter_list, &block)
mapped = nil
__update_callbacks(name, filter_list, block) do |chain, type, filters, options|
mapped ||= filters.map do |filter|
Callback.new(chain, filter, type, options.dup, self)
end
filters.each do |filter|
chain.delete_if {|c| c.matches?(type, filter) }
end
options[:prepend] ? chain.unshift(*(mapped.reverse)) : chain.push(*mapped)
end
end
# Skip a previously defined callback for a given type.
#
def skip_callback(name, *filter_list, &block)
__update_callbacks(name, filter_list, block) do |chain, type, filters, options|
filters.each do |filter|
filter = chain.find {|c| c.matches?(type, filter) }
if filter && options.any?
new_filter = filter.clone(chain, self)
chain.insert(chain.index(filter), new_filter)
new_filter.recompile!(options, options[:per_key] || {})
end
chain.delete(filter)
end
end
end
# Reset callbacks for a given type.
#
def reset_callbacks(symbol)
callbacks = send("_#{symbol}_callbacks")
ActiveSupport::DescendantsTracker.descendants(self).each do |target|
chain = target.send("_#{symbol}_callbacks")
callbacks.each { |c| chain.delete(c) }
target.__define_runner(symbol)
end
callbacks.clear
__define_runner(symbol)
end
# Defines callbacks types:
#
# define_callbacks :validate
#
# This macro accepts the following options:
#
# * <tt>:terminator</tt> - Indicates when a before filter is considered
# to be halted.
#
# define_callbacks :validate, :terminator => "result == false"
#
# In the example above, if any before validate callbacks returns +false+,
# other callbacks are not executed. Defaults to "false", meaning no value
# halts the chain.
#
# * <tt>:rescuable</tt> - By default, after filters are not executed if
# the given block or a before filter raises an error. Set this option to
# true to change this behavior.
#
# * <tt>:scope</tt> - Indicates which methods should be executed when a class
# is given as callback. Defaults to <tt>[:kind]</tt>.
#
# class Audit
# def before(caller)
# puts 'Audit: before is called'
# end
#
# def before_save(caller)
# puts 'Audit: before_save is called'
# end
# end
#
# class Account
# include ActiveSupport::Callbacks
#
# define_callbacks :save
# set_callback :save, :before, Audit.new
#
# def save
# run_callbacks :save do
# puts 'save in main'
# end
# end
# end
#
# In the above case whenever you save an account the method <tt>Audit#before</tt> will
# be called. On the other hand
#
# define_callbacks :save, :scope => [:kind, :name]
#
# would trigger <tt>Audit#before_save</tt> instead. That's constructed by calling
# <tt>"#{kind}_#{name}"</tt> on the given instance. In this case "kind" is "before" and
# "name" is "save". In this context ":kind" and ":name" have special meanings: ":kind"
# refers to the kind of callback (before/after/around) and ":name" refers to the
# method on which callbacks are being defined.
#
# A declaration like
#
# define_callbacks :save, :scope => [:name]
#
# would call <tt>Audit#save</tt>.
#
def define_callbacks(*callbacks)
config = callbacks.last.is_a?(Hash) ? callbacks.pop : {}
callbacks.each do |callback|
extlib_inheritable_reader("_#{callback}_callbacks") do
CallbackChain.new(callback, config)
end
__define_runner(callback)
end
end
end
end
end
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