441 lines
14 KiB
Ruby
441 lines
14 KiB
Ruby
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# Extracted from ActiveSupport::Callbacks written by Yehuda Katz
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# http://github.com/wycats/rails/raw/18b405f154868204a8f332888871041a7bad95e1/activesupport/lib/active_support/callbacks.rb
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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 CouchRest::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 CouchRest::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 = {})
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send("_run_#{kind}_callbacks")
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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, name)
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@kind, @klass = kind, klass
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@name = name
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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(options[:if])
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options[:unless] = Array(options[:unless])
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options[:per_key] ||= {}
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options[:per_key][:if] = Array(options[:per_key][:if])
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options[:per_key][:unless] = Array(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, _name, _filter)
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@kind == _kind &&
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@name == _name &&
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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, 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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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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[@compiled_options[0], @filter, @compiled_options[1]].compact.join("\n")
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elsif @compiled_options[0]
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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 = <<-RUBY_EVAL
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def #{name}
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#{@compiled_options[0]}
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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)
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"#{name} do"
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else
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"#{@filter} 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(_compile_filter(options[:if]))
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end
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unless options[:unless].empty?
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conditions << Array(_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 Proc
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@klass.send(:define_method, method_name, &filter)
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method_name << (filter.arity == 1 ? "(self)" : "")
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when String
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@klass.class_eval <<-RUBY_EVAL
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def #{method_name}
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#{filter}
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end
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RUBY_EVAL
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method_name
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else
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kind, name = @kind, @name
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@klass.send(:define_method, method_name) do
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filter.send("#{kind}_#{name}", self)
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end
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method_name
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end
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end
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end
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# This method_missing is supplied to catch callbacks with keys and create
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# the appropriate callback for future use.
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def method_missing(meth, *args, &blk)
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if meth.to_s =~ /_run_(\w+)_(\w+)_(\w+)_callbacks/
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return self.class._create_and_run_keyed_callback($1, $2.to_sym, $3.to_sym, self, &blk)
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end
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super
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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 compile(key = nil, object = nil)
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method = []
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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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method << "yield self"
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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.compact.join("\n")
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end
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def clone(klass)
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CallbackChain.new(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, str, options)
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self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
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def _run_#{symbol}_callbacks(key = nil)
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if key
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send("_run_\#{self.class}_#{symbol}_\#{key}_callbacks") { yield }
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else
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#{str}
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end
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end
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RUBY_EVAL
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before_name, around_name, after_name =
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options.values_at(:before, :after, :around)
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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_and_run_keyed_callback(klass, kind, key, obj, &blk)
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@_keyed_callbacks ||= {}
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@_keyed_callbacks[[kind, key]] ||= begin
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str = self.send("_#{kind}_callbacks").compile(key, obj)
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self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
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def _run_#{klass}_#{kind}_#{key}_callbacks
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#{str}
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end
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RUBY_EVAL
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true
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end
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obj.send("_run_#{klass}_#{kind}_#{key}_callbacks", &blk)
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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"}}
|
||
|
|
#
|
||
|
|
# Per-Key conditions are evaluated only once per use of a given key.
|
||
|
|
# In the case of the above example, you would do:
|
||
|
|
#
|
||
|
|
# run_dispatch_callbacks(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 define_callbacks(*symbols)
|
||
|
|
symbols.each do |symbol|
|
||
|
|
self.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
|
||
|
|
class_inheritable_accessor :_#{symbol}_callbacks
|
||
|
|
self._#{symbol}_callbacks = CallbackChain.new
|
||
|
|
|
||
|
|
def self.#{symbol}_callback(type, *filters, &blk)
|
||
|
|
options = filters.last.is_a?(Hash) ? filters.pop : {}
|
||
|
|
filters.unshift(blk) if block_given?
|
||
|
|
filters.map! {|f| Callback.new(f, type, options.dup, self, :#{symbol})}
|
||
|
|
self._#{symbol}_callbacks.push(*filters)
|
||
|
|
_define_runner(:#{symbol}, self._#{symbol}_callbacks.compile, options)
|
||
|
|
end
|
||
|
|
|
||
|
|
def self.skip_#{symbol}_callback(type, *filters, &blk)
|
||
|
|
options = filters.last.is_a?(Hash) ? filters.pop : {}
|
||
|
|
filters.unshift(blk) if block_given?
|
||
|
|
filters.each do |filter|
|
||
|
|
self._#{symbol}_callbacks = self._#{symbol}_callbacks.clone(self)
|
||
|
|
|
||
|
|
filter = self._#{symbol}_callbacks.find {|c| c.matches?(type, :#{symbol}, filter) }
|
||
|
|
per_key = options[:per_key] || {}
|
||
|
|
if filter
|
||
|
|
filter.recompile!(options, per_key)
|
||
|
|
else
|
||
|
|
self._#{symbol}_callbacks.delete(filter)
|
||
|
|
end
|
||
|
|
_define_runner(:#{symbol}, self._#{symbol}_callbacks.compile, options)
|
||
|
|
end
|
||
|
|
|
||
|
|
end
|
||
|
|
|
||
|
|
self.#{symbol}_callback(:before)
|
||
|
|
RUBY_EVAL
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|