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