533 lines
17 KiB
Ruby
533 lines
17 KiB
Ruby
# Copyright (c) 2006-2009 David Heinemeier Hansson
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#
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# Extracted from ActiveSupport::NewCallbacks written by Yehuda Katz
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# http://github.com/rails/rails/raw/d6e4113c83a9d55be6f2af247da2cecaa855f43b/activesupport/lib/active_support/new_callbacks.rb
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# http://github.com/rails/rails/commit/1126a85aed576402d978e6f76eb393b6baaa9541
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require File.join(File.dirname(__FILE__), '..', 'support', 'class')
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module CouchRest
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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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# save_callback :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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# save_callback :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_save_callbacks 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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# save_callback :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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# save_callback :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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# save_callback :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_save_callbacks 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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module Callbacks
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def self.included(klass)
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klass.extend ClassMethods
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end
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def run_callbacks(kind, options = {}, &blk)
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send("_run_#{kind}_callbacks", &blk)
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end
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class Callback
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@@_callback_sequence = 0
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attr_accessor :filter, :kind, :name, :options, :per_key, :klass
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def initialize(filter, kind, options, klass)
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@kind, @klass = 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(klass)
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obj = super()
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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 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 &&
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@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, options = {})
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object, terminator = (options || {}).values_at(:object, :terminator)
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return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
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terminator ||= false
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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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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 = (#{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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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, options = {})
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object = (options || {})[:object]
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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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# 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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# 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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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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@klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
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def #{method_name}(&blk)
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#{method_name}_object.send(:#{kind}, 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.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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def initialize(symbol)
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@symbol = symbol
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end
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def compile(key = nil, options = {})
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method = []
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method << "halted = false"
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each do |callback|
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method << callback.start(key, options)
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end
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method << "yield self if block_given? && !halted"
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reverse_each do |callback|
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method << callback.end(key, options)
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end
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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(@symbol)
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chain.push(*map {|c| c.clone(klass)})
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end
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end
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module ClassMethods
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#CHAINS = {:before => :before, :around => :before, :after => :after}
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# Make the _run_save_callbacks 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_save_callbacks do
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# save
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# end
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#
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# The _run_save_callbacks 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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def _define_runner(symbol)
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body = send("_#{symbol}_callback").
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compile(nil, :terminator => send("_#{symbol}_terminator"))
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body, line = <<-RUBY_EVAL, __LINE__ + 1
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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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RUBY_EVAL
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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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# 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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def _create_keyed_callback(name, kind, obj, &blk)
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@_keyed_callbacks ||= {}
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@_keyed_callbacks[name] ||= begin
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str = send("_#{kind}_callback").
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compile(name, :object => obj, :terminator => send("_#{kind}_terminator"))
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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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# Define callbacks.
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#
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# Creates a <name>_callback method that you can use to add callbacks.
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#
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# Syntax:
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# save_callback :before, :before_meth
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# save_callback :after, :after_meth, :if => :condition
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# save_callback :around {|r| stuff; yield; stuff }
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#
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# The <name>_callback method also updates the _run_<name>_callbacks
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# method, which is the public API to run the callbacks.
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#
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# Also creates a skip_<name>_callback method that you can use to skip
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# callbacks.
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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_dispatch_callbacks(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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def _update_callbacks(name, filters = CallbackChain.new(name), block = nil)
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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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callbacks = send("_#{name}_callback")
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yield callbacks, type, filters, options if block_given?
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_define_runner(name)
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end
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alias_method :_reset_callbacks, :_update_callbacks
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def set_callback(name, *filters, &block)
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_update_callbacks(name, filters, block) do |callbacks, type, filters, options|
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filters.map! do |filter|
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# overrides parent class
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callbacks.delete_if {|c| c.matches?(type, filter) }
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Callback.new(filter, type, options.dup, self)
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end
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options[:prepend] ? callbacks.unshift(*filters) : callbacks.push(*filters)
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end
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end
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def skip_callback(name, *filters, &block)
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_update_callbacks(name, filters, block) do |callbacks, type, filters, options|
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filters.each do |filter|
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callbacks = send("_#{name}_callback=", callbacks.clone(self))
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filter = callbacks.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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callbacks.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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def define_callbacks(*symbols)
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terminator = symbols.pop if symbols.last.is_a?(String)
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symbols.each do |symbol|
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extlib_inheritable_accessor("_#{symbol}_terminator") { terminator }
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extlib_inheritable_accessor("_#{symbol}_callback") do
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CallbackChain.new(symbol)
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end
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_define_runner(symbol)
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# Define more convenient callback methods
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# set_callback(:save, :before) becomes before_save
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[:before, :after, :around].each do |filter|
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self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
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def self.#{filter}_#{symbol}(*symbols, &blk)
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_alias_callbacks(symbols, blk) do |callback, options|
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set_callback(:#{symbol}, :#{filter}, callback, options)
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end
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end
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RUBY_EVAL
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end
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end
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end
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def _alias_callbacks(callbacks, block)
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options = callbacks.last.is_a?(Hash) ? callbacks.pop : {}
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callbacks.push(block) if block
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callbacks.each do |callback|
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yield callback, options
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end
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end
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end
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end
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end
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