Callbacks, DeprecatedCallbacks = NewCallbacks, Callbacks

1 files changed, 452 insertions, 170 deletions

diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 238d1b6804..21388d7a58 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -1,4 +1,6 @@
-require 'active_support/core_ext/array/extract_options'
+require 'active_support/core_ext/array/wrap'
+require 'active_support/core_ext/class/inheritable_attributes'
+require 'active_support/core_ext/kernel/reporting'
 
 module ActiveSupport
   # Callbacks are hooks into the lifecycle of an object that allow you to trigger logic
@@ -10,23 +12,23 @@ module ActiveSupport
   #   class Storage
   #     include ActiveSupport::Callbacks
   #
-  #     define_callbacks :before_save, :after_save
+  #     define_callbacks :save
   #   end
   #
   #   class ConfigStorage < Storage
-  #     before_save :saving_message
+  #     set_callback :save, :before, :saving_message
   #     def saving_message
   #       puts "saving..."
   #     end
   #
-  #     after_save do |object|
+  #     set_callback :save, :after do |object|
   #       puts "saved"
   #     end
   #
   #     def save
-  #       run_callbacks(:before_save)
-  #       puts "- save"
-  #       run_callbacks(:after_save)
+  #       run_callbacks :save do
+  #         puts "- save"
+  #       end
   #     end
   #   end
   #
@@ -44,28 +46,28 @@ module ActiveSupport
   #   class Storage
   #     include ActiveSupport::Callbacks
   #
-  #     define_callbacks :before_save, :after_save
+  #     define_callbacks :save
   #
-  #     before_save :prepare
+  #     set_callback :save, :before, :prepare
   #     def prepare
   #       puts "preparing save"
   #     end
   #   end
   #
   #   class ConfigStorage < Storage
-  #     before_save :saving_message
+  #     set_callback :save, :before, :saving_message
   #     def saving_message
   #       puts "saving..."
   #     end
   #
-  #     after_save do |object|
+  #     set_callback :save, :after do |object|
   #       puts "saved"
   #     end
   #
   #     def save
-  #       run_callbacks(:before_save)
-  #       puts "- save"
-  #       run_callbacks(:after_save)
+  #       run_callbacks :save do
+  #         puts "- save"
+  #       end
   #     end
   #   end
   #
@@ -77,205 +79,485 @@ module ActiveSupport
   #   saving...
   #   - save
   #   saved
+  #
   module Callbacks
-    class CallbackChain < Array
-      def self.build(kind, *methods, &block)
-        methods, options = extract_options(*methods, &block)
-        methods.map! { |method| Callback.new(kind, method, options) }
-        new(methods)
+    def self.included(klass)
+      klass.extend ClassMethods
+    end
+
+    def run_callbacks(kind, *args, &block)
+      send("_run_#{kind}_callbacks", *args, &block)
+    end
+
+    class Callback
+      @@_callback_sequence = 0
+
+      attr_accessor :chain, :filter, :kind, :options, :per_key, :klass
+
+      def initialize(chain, filter, kind, options, klass)
+        @chain, @kind, @klass = chain, kind, klass
+        normalize_options!(options)
+
+        @per_key              = options.delete(:per_key)
+        @raw_filter, @options = filter, options
+        @filter               = _compile_filter(filter)
+        @compiled_options     = _compile_options(options)
+        @callback_id          = next_id
+
+        _compile_per_key_options
+      end
+
+      def clone(chain, klass)
+        obj                  = super()
+        obj.chain            = chain
+        obj.klass            = klass
+        obj.per_key          = @per_key.dup
+        obj.options          = @options.dup
+        obj.per_key[:if]     = @per_key[:if].dup
+        obj.per_key[:unless] = @per_key[:unless].dup
+        obj.options[:if]     = @options[:if].dup
+        obj.options[:unless] = @options[:unless].dup
+        obj
       end
 
-      def run(object, options = {}, &terminator)
-        enumerator = options[:enumerator] || :each
+      def normalize_options!(options)
+        options[:if] = Array.wrap(options[:if])
+        options[:unless] = Array.wrap(options[:unless])
 
-        unless block_given?
-          send(enumerator) { |callback| callback.call(object) }
-        else
-          send(enumerator) do |callback|
-            result = callback.call(object)
-            break result if terminator.call(result, object)
+        options[:per_key] ||= {}
+        options[:per_key][:if] = Array.wrap(options[:per_key][:if])
+        options[:per_key][:unless] = Array.wrap(options[:per_key][:unless])
+      end
+
+      def name
+        chain.name
+      end
+
+      def next_id
+        @@_callback_sequence += 1
+      end
+
+      def matches?(_kind, _filter)
+        @kind == _kind && @filter == _filter
+      end
+
+      def _update_filter(filter_options, new_options)
+        filter_options[:if].push(new_options[:unless]) if new_options.key?(:unless)
+        filter_options[:unless].push(new_options[:if]) if new_options.key?(:if)
+      end
+
+      def recompile!(_options, _per_key)
+        _update_filter(self.options, _options)
+        _update_filter(self.per_key, _per_key)
+
+        @callback_id      = next_id
+        @filter           = _compile_filter(@raw_filter)
+        @compiled_options = _compile_options(@options)
+                            _compile_per_key_options
+      end
+
+      def _compile_per_key_options
+        key_options  = _compile_options(@per_key)
+
+        @klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
+          def _one_time_conditions_valid_#{@callback_id}?
+            true #{key_options[0]}
           end
-        end
+        RUBY_EVAL
       end
 
-      # TODO: Decompose into more Array like behavior
-      def replace_or_append!(chain)
-        if index = index(chain)
-          self[index] = chain
-        else
-          self << chain
+      # This will supply contents for before and around filters, and no
+      # contents for after filters (for the forward pass).
+      def start(key=nil, object=nil)
+        return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
+
+        # options[0] is the compiled form of supplied conditions
+        # options[1] is the "end" for the conditional
+        #
+        if @kind == :before || @kind == :around
+          if @kind == :before
+            # if condition    # before_save :filter_name, :if => :condition
+            #   filter_name
+            # end
+            filter = <<-RUBY_EVAL
+              unless halted
+                result = #{@filter}
+                halted = (#{chain.config[:terminator]})
+              end
+            RUBY_EVAL
+
+            [@compiled_options[0], filter, @compiled_options[1]].compact.join("\n")
+          else
+            # Compile around filters with conditions into proxy methods
+            # that contain the conditions.
+            #
+            # For `around_save :filter_name, :if => :condition':
+            #
+            # def _conditional_callback_save_17
+            #   if condition
+            #     filter_name do
+            #       yield self
+            #     end
+            #   else
+            #     yield self
+            #   end
+            # end
+            #
+            name = "_conditional_callback_#{@kind}_#{next_id}"
+            txt, line = <<-RUBY_EVAL, __LINE__ + 1
+              def #{name}(halted)
+                #{@compiled_options[0] || "if true"} && !halted
+                  #{@filter} do
+                    yield self
+                  end
+                else
+                  yield self
+                end
+              end
+            RUBY_EVAL
+            @klass.class_eval(txt, __FILE__, line)
+            "#{name}(halted) do"
+          end
         end
-        self
       end
 
-      def find(callback, &block)
-        select { |c| c == callback && (!block_given? || yield(c)) }.first
-      end
+      # This will supply contents for around and after filters, but not
+      # before filters (for the backward pass).
+      def end(key=nil, object=nil)
+        return if key && !object.send("_one_time_conditions_valid_#{@callback_id}?")
 
-      def delete(callback)
-        super(callback.is_a?(Callback) ? callback : find(callback))
+        if @kind == :around || @kind == :after
+          # if condition    # after_save :filter_name, :if => :condition
+          #   filter_name
+          # end
+          if @kind == :after
+            [@compiled_options[0], @filter, @compiled_options[1]].compact.join("\n")
+          else
+            "end"
+          end
+        end
       end
 
       private
-        def self.extract_options(*methods, &block)
-          methods.flatten!
-          options = methods.extract_options!
-          methods << block if block_given?
-          return methods, options
-        end
 
-        def extract_options(*methods, &block)
-          self.class.extract_options(*methods, &block)
+      # Options support the same options as filters themselves (and support
+      # symbols, string, procs, and objects), so compile a conditional
+      # expression based on the options
+      def _compile_options(options)
+        return [] if options[:if].empty? && options[:unless].empty?
+
+        conditions = []
+
+        unless options[:if].empty?
+          conditions << Array.wrap(_compile_filter(options[:if]))
         end
-    end
 
-    class Callback
-      attr_reader :kind, :method, :identifier, :options
+        unless options[:unless].empty?
+          conditions << Array.wrap(_compile_filter(options[:unless])).map {|f| "!#{f}"}
+        end
 
-      def initialize(kind, method, options = {})
-        @kind       = kind
-        @method     = method
-        @identifier = options[:identifier]
-        @options    = options
+        ["if #{conditions.flatten.join(" && ")}", "end"]
       end
 
-      def ==(other)
-        case other
-        when Callback
-          (self.identifier && self.identifier == other.identifier) || self.method == other.method
+      # Filters support:
+      #
+      #   Arrays::  Used in conditions. This is used to specify
+      #             multiple conditions. Used internally to
+      #             merge conditions from skip_* filters
+      #   Symbols:: A method to call
+      #   Strings:: Some content to evaluate
+      #   Procs::   A proc to call with the object
+      #   Objects:: An object with a before_foo method on it to call
+      #
+      # All of these objects are compiled into methods and handled
+      # the same after this point:
+      #
+      #   Arrays::  Merged together into a single filter
+      #   Symbols:: Already methods
+      #   Strings:: class_eval'ed into methods
+      #   Procs::   define_method'ed into methods
+      #   Objects::
+      #     a method is created that calls the before_foo method
+      #     on the object.
+      #
+      def _compile_filter(filter)
+        method_name = "_callback_#{@kind}_#{next_id}"
+        case filter
+        when Array
+          filter.map {|f| _compile_filter(f)}
+        when Symbol
+          filter
+        when String
+          "(#{filter})"
+        when Proc
+          @klass.send(:define_method, method_name, &filter)
+          return method_name if filter.arity <= 0
+
+          method_name << (filter.arity == 1 ? "(self)" : " self, Proc.new ")
         else
-          (self.identifier && self.identifier == other) || self.method == other
+          @klass.send(:define_method, "#{method_name}_object") { filter }
+
+          _normalize_legacy_filter(kind, filter)
+          scopes = Array.wrap(chain.config[:scope])
+          method_to_call = scopes.map{ |s| s.is_a?(Symbol) ? send(s) : s }.join("_")
+
+          @klass.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
+            def #{method_name}(&blk)
+              #{method_name}_object.send(:#{method_to_call}, self, &blk)
+            end
+          RUBY_EVAL
+
+          method_name
         end
       end
 
-      def eql?(other)
-        self == other
+      def _normalize_legacy_filter(kind, filter)
+        if !filter.respond_to?(kind) && filter.respond_to?(:filter)
+          filter.metaclass.class_eval(
+            "def #{kind}(context, &block) filter(context, &block) end",
+            __FILE__, __LINE__ - 1)
+        elsif filter.respond_to?(:before) && filter.respond_to?(:after) && kind == :around
+          def filter.around(context)
+            should_continue = before(context)
+            yield if should_continue
+            after(context)
+          end
+        end
       end
+    end
 
-      def dup
-        self.class.new(@kind, @method, @options.dup)
+    # An Array with a compile method
+    class CallbackChain < Array
+      attr_reader :name, :config
+
+      def initialize(name, config)
+        @name = name
+        @config = {
+          :terminator => "false",
+          :rescuable => false,
+          :scope => [ :kind ]
+        }.merge(config)
       end
 
-      def hash
-        if @identifier
-          @identifier.hash
-        else
-          @method.hash
+      def compile(key=nil, object=nil)
+        method = []
+        method << "value = nil"
+        method << "halted = false"
+
+        each do |callback|
+          method << callback.start(key, object)
+        end
+
+        if config[:rescuable]
+          method << "rescued_error = nil"
+          method << "begin"
+        end
+
+        method << "value = yield if block_given? && !halted"
+
+        if config[:rescuable]
+          method << "rescue Exception => e"
+          method << "rescued_error = e"
+          method << "end"
         end
+
+        reverse_each do |callback|
+          method << callback.end(key, object)
+        end
+
+        method << "raise rescued_error if rescued_error" if config[:rescuable]
+        method << "halted ? false : (block_given? ? value : true)"
+        method.compact.join("\n")
       end
 
-      def call(*args, &block)
-        evaluate_method(method, *args, &block) if should_run_callback?(*args)
-      rescue LocalJumpError
-        raise ArgumentError,
-          "Cannot yield from a Proc type filter. The Proc must take two " +
-          "arguments and execute #call on the second argument."
+      def clone(klass)
+        chain = CallbackChain.new(@name, @config.dup)
+        callbacks = map { |c| c.clone(chain, klass) }
+        chain.push(*callbacks)
       end
+    end
 
-      private
-        def evaluate_method(method, *args, &block)
-          case method
-            when Symbol
-              object = args.shift
-              object.send(method, *args, &block)
-            when String
-              eval(method, args.first.instance_eval { binding })
-            when Proc, Method
-              method.call(*args, &block)
-            else
-              if method.respond_to?(kind)
-                method.send(kind, *args, &block)
-              else
-                raise ArgumentError,
-                  "Callbacks must be a symbol denoting the method to call, a string to be evaluated, " +
-                  "a block to be invoked, or an object responding to the callback method."
+    module ClassMethods
+      # Make the run_callbacks :save method. The generated method takes
+      # a block that it'll yield to. It'll call the before and around filters
+      # in order, yield the block, and then run the after filters.
+      #
+      # run_callbacks :save do
+      #   save
+      # end
+      #
+      # The run_callbacks :save method can optionally take a key, which
+      # will be used to compile an optimized callback method for each
+      # key. See #define_callbacks for more information.
+      #
+      def __define_runner(symbol) #:nodoc:
+        body = send("_#{symbol}_callbacks").compile(nil)
+
+        body, line = <<-RUBY_EVAL, __LINE__
+          def _run_#{symbol}_callbacks(key = nil, &blk)
+            if key
+              name = "_run__\#{self.class.name.hash.abs}__#{symbol}__\#{key.hash.abs}__callbacks"
+
+              unless respond_to?(name)
+                self.class.__create_keyed_callback(name, :#{symbol}, self, &blk)
               end
+
+              send(name, &blk)
+            else
+              #{body}
+            end
           end
+          private :_run_#{symbol}_callbacks
+        RUBY_EVAL
+
+        silence_warnings do
+          undef_method "_run_#{symbol}_callbacks" if method_defined?("_run_#{symbol}_callbacks")
+          class_eval body, __FILE__, line
         end
+      end
 
-        def should_run_callback?(*args)
-          [options[:if]].flatten.compact.all? { |a| evaluate_method(a, *args) } &&
-          ![options[:unless]].flatten.compact.any? { |a| evaluate_method(a, *args) }
+      # This is called the first time a callback is called with a particular
+      # key. It creates a new callback method for the key, calculating
+      # which callbacks can be omitted because of per_key conditions.
+      #
+      def __create_keyed_callback(name, kind, object, &blk) #:nodoc:
+        @_keyed_callbacks ||= {}
+        @_keyed_callbacks[name] ||= begin
+          str = send("_#{kind}_callbacks").compile(name, object)
+          class_eval "def #{name}() #{str} end", __FILE__, __LINE__
+          true
         end
-    end
+      end
 
-    def self.included(base)
-      base.extend ClassMethods
-    end
+      # This is used internally to append, prepend and skip callbacks to the
+      # CallbackChain.
+      #
+      def __update_callbacks(name, filters = [], block = nil) #:nodoc:
+        type = [:before, :after, :around].include?(filters.first) ? filters.shift : :before
+        options = filters.last.is_a?(Hash) ? filters.pop : {}
+        filters.unshift(block) if block
 
-    module ClassMethods
-      def define_callbacks(*callbacks)
-        callbacks.each do |callback|
-          class_eval <<-"end_eval", __FILE__, __LINE__ + 1
-            def self.#{callback}(*methods, &block)                             # def self.before_save(*methods, &block)
-              callbacks = CallbackChain.build(:#{callback}, *methods, &block)  #   callbacks = CallbackChain.build(:before_save, *methods, &block)
-              @#{callback}_callbacks ||= CallbackChain.new                     #   @before_save_callbacks ||= CallbackChain.new
-              @#{callback}_callbacks.concat callbacks                          #   @before_save_callbacks.concat callbacks
-            end                                                                # end
-                                                                               #
-            def self.#{callback}_callback_chain                                # def self.before_save_callback_chain
-              @#{callback}_callbacks ||= CallbackChain.new                     #   @before_save_callbacks ||= CallbackChain.new
-                                                                               #
-              if superclass.respond_to?(:#{callback}_callback_chain)           #   if superclass.respond_to?(:before_save_callback_chain)
-                CallbackChain.new(                                             #     CallbackChain.new(
-                  superclass.#{callback}_callback_chain +                      #       superclass.before_save_callback_chain +
-                  @#{callback}_callbacks                                       #       @before_save_callbacks
-                )                                                              #     )
-              else                                                             #   else
-                @#{callback}_callbacks                                         #     @before_save_callbacks
-              end                                                              #   end
-            end                                                                # end
-          end_eval
+        chain = send("_#{name}_callbacks")
+        yield chain, type, filters, options if block_given?
+
+        __define_runner(name)
+      end
+
+      # Set callbacks for a previously defined callback.
+      #
+      # Syntax:
+      #   set_callback :save, :before, :before_meth
+      #   set_callback :save, :after,  :after_meth, :if => :condition
+      #   set_callback :save, :around, lambda { |r| stuff; yield; stuff }
+      #
+      # Use skip_callback to skip any defined one.
+      #
+      # When creating or skipping callbacks, you can specify conditions that
+      # are always the same for a given key. For instance, in ActionPack,
+      # we convert :only and :except conditions into per-key conditions.
+      #
+      #   before_filter :authenticate, :except => "index"
+      # becomes
+      #   dispatch_callback :before, :authenticate, :per_key => {:unless => proc {|c| c.action_name == "index"}}
+      #
+      # Per-Key conditions are evaluated only once per use of a given key.
+      # In the case of the above example, you would do:
+      #
+      #   run_callbacks(:dispatch, action_name) { ... dispatch stuff ... }
+      #
+      # In that case, each action_name would get its own compiled callback
+      # method that took into consideration the per_key conditions. This
+      # is a speed improvement for ActionPack.
+      #
+      def set_callback(name, *filters, &block)
+        __update_callbacks(name, filters, block) do |chain, type, filters, options|
+          filters.map! do |filter|
+            chain.delete_if {|c| c.matches?(type, filter) }
+            Callback.new(chain, filter, type, options.dup, self)
+          end
+
+          options[:prepend] ? chain.unshift(*filters) : chain.push(*filters)
         end
       end
-    end
 
-    # Runs all the callbacks defined for the given options.
-    #
-    # If a block is given it will be called after each callback receiving as arguments:
-    #
-    #  * the result from the callback
-    #  * the object which has the callback
-    #
-    # If the result from the block evaluates to +true+, the callback chain is stopped.
-    #
-    # Example:
-    #   class Storage
-    #     include ActiveSupport::Callbacks
-    #
-    #     define_callbacks :before_save, :after_save
-    #   end
-    #
-    #   class ConfigStorage < Storage
-    #     before_save :pass
-    #     before_save :pass
-    #     before_save :stop
-    #     before_save :pass
-    #
-    #     def pass
-    #       puts "pass"
-    #     end
-    #
-    #     def stop
-    #       puts "stop"
-    #       return false
-    #     end
-    #
-    #     def save
-    #       result = run_callbacks(:before_save) { |result, object| result == false }
-    #       puts "- save" if result
-    #     end
-    #   end
-    #
-    #   config = ConfigStorage.new
-    #   config.save
-    #
-    # Output:
-    #   pass
-    #   pass
-    #   stop
-    def run_callbacks(kind, options = {}, &block)
-      self.class.send("#{kind}_callback_chain").run(self, options, &block)
+      # Skip a previously defined callback for a given type.
+      #
+      def skip_callback(name, *filters, &block)
+        __update_callbacks(name, filters, block) do |chain, type, filters, options|
+          chain = send("_#{name}_callbacks=", chain.clone(self))
+
+          filters.each do |filter|
+            filter = chain.find {|c| c.matches?(type, filter) }
+
+            if filter && options.any?
+              filter.recompile!(options, options[:per_key] || {})
+            else
+              chain.delete(filter)
+            end
+          end
+        end
+      end
+
+      # Reset callbacks for a given type.
+      #
+      def reset_callbacks(symbol)
+        send("_#{symbol}_callbacks").clear
+        __define_runner(symbol)
+      end
+
+      # Define callbacks types.
+      #
+      # ==== Example
+      #
+      #   define_callbacks :validate
+      #
+      # ==== Options
+      #
+      # * <tt>:terminator</tt> - Indicates when a before filter is considered
+      # to be halted.
+      #
+      #   define_callbacks :validate, :terminator => "result == false"
+      #
+      # In the example above, if any before validate callbacks returns false,
+      # other callbacks are not executed. Defaults to "false".
+      #
+      # * <tt>:rescuable</tt> - By default, after filters are not executed if
+      # the given block or an before_filter raises an error. Supply :rescuable => true
+      # to change this behavior.
+      #
+      # * <tt>:scope</tt> - Show which methods should be executed when a class
+      # is giben as callback:
+      #
+      #   define_callbacks :filters, :scope => [ :kind ]
+      #
+      # When a class is given:
+      #
+      #   before_filter MyFilter
+      #
+      # It will call the type of the filter in the given class, which in this
+      # case, is "before".
+      #
+      # If, for instance, you supply the given scope:
+      #
+      #   define_callbacks :validate, :scope => [ :kind, :name ]
+      #
+      # It will call "#{kind}_#{name}" in the given class. So "before_validate"
+      # will be called in the class below:
+      #
+      #   before_validate MyValidation
+      #
+      # Defaults to :kind.
+      #
+      def define_callbacks(*symbols)
+        config = symbols.last.is_a?(Hash) ? symbols.pop : {}
+        symbols.each do |symbol|
+          extlib_inheritable_accessor("_#{symbol}_callbacks") do
+            CallbackChain.new(symbol, config)
+          end
+
+          __define_runner(symbol)
+        end
+      end
     end
   end
 end