lib/active_support/dependencies.rb in activesupport-3.0.0.beta4 vs lib/active_support/dependencies.rb in activesupport-3.0.pre

@@ -1,12 +1,10 @@
 require 'set'
 require 'thread'
-require 'pathname'
 require 'active_support/core_ext/module/aliasing'
 require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/module/introspection'
-require 'active_support/core_ext/module/anonymous'
 require 'active_support/core_ext/object/blank'
 require 'active_support/core_ext/load_error'
 require 'active_support/core_ext/name_error'
 require 'active_support/core_ext/string/starts_ends_with'
 require 'active_support/inflector'
@@ -45,13 +43,10 @@
     # An array of qualified constant names that have been loaded. Adding a name to
     # this array will cause it to be unloaded the next time Dependencies are cleared.
     mattr_accessor :autoloaded_constants
     self.autoloaded_constants = []
 
-    mattr_accessor :references
-    self.references = {}
-
     # An array of constant names that need to be unloaded on every request. Used
     # to allow arbitrary constants to be marked for unloading.
     mattr_accessor :explicitly_unloadable_constants
     self.explicitly_unloadable_constants = []
 
@@ -61,159 +56,125 @@
 
     # Set to true to enable logging of const_missing and file loads
     mattr_accessor :log_activity
     self.log_activity = false
 
-    class WatchStack < Array
-      def initialize
-        @mutex = Mutex.new
-      end
-
-      def self.locked(*methods)
-        methods.each { |m| class_eval "def #{m}(*) lock { super } end", __FILE__, __LINE__ }
-      end
-
-      def get(key)
-        (val = assoc(key)) ? val[1] : []
-      end
-
-      locked :concat, :each, :delete_if, :<<
-
-      def new_constants_for(frames)
-        constants = []
-        frames.each do |mod_name, prior_constants|
-          mod = Inflector.constantize(mod_name) if Dependencies.qualified_const_defined?(mod_name)
-          next unless mod.is_a?(Module)
-
-          new_constants = mod.local_constant_names - prior_constants
-          get(mod_name).concat(new_constants)
-
-          new_constants.each do |suffix|
-            constants << ([mod_name, suffix] - ["Object"]).join("::")
-          end
-        end
-        constants
-      end
-
-      # Add a set of modules to the watch stack, remembering the initial constants
-      def add_modules(modules)
-        list = modules.map do |desc|
-          name = Dependencies.to_constant_name(desc)
-          consts = Dependencies.qualified_const_defined?(name) ?
-            Inflector.constantize(name).local_constant_names : []
-          [name, consts]
-        end
-        concat(list)
-        list
-      end
-
-      def lock
-        @mutex.synchronize { yield self }
-      end
-    end
-
     # An internal stack used to record which constants are loaded by any block.
     mattr_accessor :constant_watch_stack
-    self.constant_watch_stack = WatchStack.new
+    self.constant_watch_stack = []
 
+    mattr_accessor :constant_watch_stack_mutex
+    self.constant_watch_stack_mutex = Mutex.new
+
     # Module includes this module
     module ModuleConstMissing #:nodoc:
-      def self.append_features(base)
+      def self.included(base) #:nodoc:
         base.class_eval do
-          # Emulate #exclude via an ivar
-          return if defined?(@_const_missing) && @_const_missing
-          @_const_missing = instance_method(:const_missing)
-          remove_method(:const_missing)
+          unless defined? const_missing_without_dependencies
+            alias_method_chain :const_missing, :dependencies
+          end
         end
-        super
       end
 
-      def self.exclude_from(base)
+      def self.excluded(base) #:nodoc:
         base.class_eval do
-          define_method :const_missing, @_const_missing
-          @_const_missing = nil
+          if defined? const_missing_without_dependencies
+            undef_method :const_missing
+            alias_method :const_missing, :const_missing_without_dependencies
+            undef_method :const_missing_without_dependencies
+          end
         end
       end
 
       # Use const_missing to autoload associations so we don't have to
       # require_association when using single-table inheritance.
-      def const_missing(const_name, nesting = nil)
-        klass_name = name.presence || "Object"
+      def const_missing_with_dependencies(class_id)
+        ActiveSupport::Dependencies.load_missing_constant self, class_id
+      end
 
-        if !nesting
-          # We'll assume that the nesting of Foo::Bar is ["Foo::Bar", "Foo"]
-          # even though it might not be, such as in the case of
-          # class Foo::Bar; Baz; end
-          nesting = []
-          klass_name.to_s.scan(/::|$/) { nesting.unshift $` }
-        end
+      def unloadable(const_desc = self)
+        super(const_desc)
+      end
+    end
 
-        # If there are multiple levels of nesting to search under, the top
-        # level is the one we want to report as the lookup fail.
-        error = nil
-
-        nesting.each do |namespace|
+    # Class includes this module
+    module ClassConstMissing #:nodoc:
+      def const_missing(const_name)
+        if [Object, Kernel].include?(self) || parent == self
+          super
+        else
           begin
-            return Dependencies.load_missing_constant namespace.constantize, const_name
-          rescue NoMethodError then raise
+            begin
+              Dependencies.load_missing_constant self, const_name
+            rescue NameError
+              parent.send :const_missing, const_name
+            end
           rescue NameError => e
-            error ||= e
+            # Make sure that the name we are missing is the one that caused the error
+            parent_qualified_name = Dependencies.qualified_name_for parent, const_name
+            raise unless e.missing_name? parent_qualified_name
+            qualified_name = Dependencies.qualified_name_for self, const_name
+            raise NameError.new("uninitialized constant #{qualified_name}").copy_blame!(e)
           end
         end
-
-        # Raise the first error for this set. If this const_missing came from an
-        # earlier const_missing, this will result in the real error bubbling
-        # all the way up
-        raise error
       end
-
-      def unloadable(const_desc = self)
-        super(const_desc)
-      end
     end
 
     # Object includes this module
     module Loadable #:nodoc:
-      def self.exclude_from(base)
-        base.class_eval { define_method(:load, Kernel.instance_method(:load)) }
+      def self.included(base) #:nodoc:
+        base.class_eval do
+          unless defined? load_without_new_constant_marking
+            alias_method_chain :load, :new_constant_marking
+          end
+        end
       end
 
+      def self.excluded(base) #:nodoc:
+        base.class_eval do
+          if defined? load_without_new_constant_marking
+            undef_method :load
+            alias_method :load, :load_without_new_constant_marking
+            undef_method :load_without_new_constant_marking
+          end
+        end
+      end
+
       def require_or_load(file_name)
         Dependencies.require_or_load(file_name)
       end
 
       def require_dependency(file_name, message = "No such file to load -- %s")
-        unless file_name.is_a?(String)
-          raise ArgumentError, "the file name must be a String -- you passed #{file_name.inspect}"
-        end
-
         Dependencies.depend_on(file_name, false, message)
       end
 
       def require_association(file_name)
         Dependencies.associate_with(file_name)
       end
 
-      def load_dependency(file)
+      def load_with_new_constant_marking(file, *extras) #:nodoc:
         if Dependencies.load?
-          Dependencies.new_constants_in(Object) { yield }.presence
+          Dependencies.new_constants_in(Object) { load_without_new_constant_marking(file, *extras) }
         else
-          yield
+          load_without_new_constant_marking(file, *extras)
         end
       rescue Exception => exception  # errors from loading file
         exception.blame_file! file
         raise
       end
 
-      def load(file, *)
-        load_dependency(file) { super }
+      def require(file, *extras) #:nodoc:
+        if Dependencies.load?
+          Dependencies.new_constants_in(Object) { super }
+        else
+          super
+        end
+      rescue Exception => exception  # errors from required file
+        exception.blame_file! file
+        raise
       end
 
-      def require(file, *)
-        load_dependency(file) { super }
-      end
-
       # Mark the given constant as unloadable. Unloadable constants are removed each
       # time dependencies are cleared.
       #
       # Note that marking a constant for unloading need only be done once. Setup
       # or init scripts may list each unloadable constant that may need unloading;
@@ -250,19 +211,20 @@
         self
       end
     end
 
     def hook!
-      Object.class_eval { include Loadable }
-      Module.class_eval { include ModuleConstMissing }
-      Exception.class_eval { include Blamable }
+      Object.instance_eval { include Loadable }
+      Module.instance_eval { include ModuleConstMissing }
+      Class.instance_eval { include ClassConstMissing }
+      Exception.instance_eval { include Blamable }
       true
     end
 
     def unhook!
-      ModuleConstMissing.exclude_from(Module)
-      Loadable.exclude_from(Object)
+      ModuleConstMissing.excluded(Module)
+      Loadable.excluded(Object)
       true
     end
 
     def load?
       mechanism == :load
@@ -272,11 +234,11 @@
       path = search_for_file(file_name)
       require_or_load(path || file_name)
     rescue LoadError => load_error
       unless swallow_load_errors
         if file_name = load_error.message[/ -- (.*?)(\.rb)?$/, 1]
-          raise LoadError.new(message % file_name).copy_blame!(load_error)
+          raise MissingSourceFile.new(message % file_name, load_error.path).copy_blame!(load_error)
         end
         raise
       end
     end
 
@@ -328,47 +290,63 @@
       return result
     end
 
     # Is the provided constant path defined?
     def qualified_const_defined?(path)
-      names = path.sub(/^::/, '').to_s.split('::')
+      raise NameError, "#{path.inspect} is not a valid constant name!" unless
+        /^(::)?([A-Z]\w*)(::[A-Z]\w*)*$/ =~ path
 
+      names = path.to_s.split('::')
+      names.shift if names.first.empty?
+
+      # We can't use defined? because it will invoke const_missing for the parent
+      # of the name we are checking.
       names.inject(Object) do |mod, name|
-        return false unless local_const_defined?(mod, name)
+        return false unless uninherited_const_defined?(mod, name)
         mod.const_get name
       end
+      return true
     end
 
     if Module.method(:const_defined?).arity == 1
       # Does this module define this constant?
       # Wrapper to accomodate changing Module#const_defined? in Ruby 1.9
-      def local_const_defined?(mod, const)
+      def uninherited_const_defined?(mod, const)
         mod.const_defined?(const)
       end
     else
-      def local_const_defined?(mod, const) #:nodoc:
+      def uninherited_const_defined?(mod, const) #:nodoc:
         mod.const_defined?(const, false)
       end
     end
 
     # Given +path+, a filesystem path to a ruby file, return an array of constant
     # paths which would cause Dependencies to attempt to load this file.
     def loadable_constants_for_path(path, bases = load_paths)
-      expanded_path = Pathname.new(path[/\A(.*?)(\.rb)?\Z/, 1]).expand_path
+      path = $1 if path =~ /\A(.*)\.rb\Z/
+      expanded_path = File.expand_path(path)
 
-      bases.inject([]) do |paths, root|
-        expanded_root = Pathname.new(root).expand_path
-        nesting = expanded_path.relative_path_from(expanded_root).to_s
-        next paths if nesting =~ /\.\./
-        paths << nesting.camelize
-      end.uniq
+      bases.collect do |root|
+        expanded_root = File.expand_path(root)
+        next unless %r{\A#{Regexp.escape(expanded_root)}(/|\\)} =~ expanded_path
+
+        nesting = expanded_path[(expanded_root.size)..-1]
+        nesting = nesting[1..-1] if nesting && nesting[0] == ?/
+        next if nesting.blank?
+        nesting_camel = nesting.camelize
+        begin
+          qualified_const_defined?(nesting_camel)
+        rescue NameError
+          next
+        end
+        [ nesting_camel ]
+      end.flatten.compact.uniq
     end
 
     # Search for a file in load_paths matching the provided suffix.
     def search_for_file(path_suffix)
-      path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb")
-
+      path_suffix = "#{path_suffix}.rb" unless path_suffix =~ /\.rb\Z/
       load_paths.each do |root|
         path = File.join(root, path_suffix)
         return path if File.file? path
       end
       nil # Gee, I sure wish we had first_match ;-)
@@ -413,11 +391,11 @@
       const_paths = [const_paths].compact unless const_paths.is_a? Array
       parent_paths = const_paths.collect { |const_path| /(.*)::[^:]+\Z/ =~ const_path ? $1 : :Object }
 
       result = nil
       newly_defined_paths = new_constants_in(*parent_paths) do
-        result = Kernel.load path
+        result = load_without_new_constant_marking path
       end
 
       autoloaded_constants.concat newly_defined_paths unless load_once_path?(path)
       autoloaded_constants.uniq!
       log "loading #{path} defined #{newly_defined_paths * ', '}" unless newly_defined_paths.empty?
@@ -425,42 +403,50 @@
     end
 
     # Return the constant path for the provided parent and constant name.
     def qualified_name_for(mod, name)
       mod_name = to_constant_name mod
-      mod_name == "Object" ? name.to_s : "#{mod_name}::#{name}"
+      (%w(Object Kernel).include? mod_name) ? name.to_s : "#{mod_name}::#{name}"
     end
 
     # Load the constant named +const_name+ which is missing from +from_mod+. If
     # it is not possible to load the constant into from_mod, try its parent module
     # using const_missing.
     def load_missing_constant(from_mod, const_name)
       log_call from_mod, const_name
+      if from_mod == Kernel
+        if ::Object.const_defined?(const_name)
+          log "Returning Object::#{const_name} for Kernel::#{const_name}"
+          return ::Object.const_get(const_name)
+        else
+          log "Substituting Object for Kernel"
+          from_mod = Object
+        end
+      end
 
-      unless qualified_const_defined?(from_mod.name) && Inflector.constantize(from_mod.name).equal?(from_mod)
+      # If we have an anonymous module, all we can do is attempt to load from Object.
+      from_mod = Object if from_mod.name.blank?
+
+      unless qualified_const_defined?(from_mod.name) && Inflector.constantize(from_mod.name).object_id == from_mod.object_id
         raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
       end
 
-      raise ArgumentError, "#{from_mod} is not missing constant #{const_name}!" if local_const_defined?(from_mod, const_name)
+      raise ArgumentError, "#{from_mod} is not missing constant #{const_name}!" if uninherited_const_defined?(from_mod, const_name)
 
       qualified_name = qualified_name_for from_mod, const_name
       path_suffix = qualified_name.underscore
-
-      trace = caller.reject {|l| l =~ %r{#{Regexp.escape(__FILE__)}}}
       name_error = NameError.new("uninitialized constant #{qualified_name}")
-      name_error.set_backtrace(trace)
 
       file_path = search_for_file(path_suffix)
-
       if file_path && ! loaded.include?(File.expand_path(file_path)) # We found a matching file to load
         require_or_load file_path
-        raise LoadError, "Expected #{file_path} to define #{qualified_name}" unless local_const_defined?(from_mod, const_name)
+        raise LoadError, "Expected #{file_path} to define #{qualified_name}" unless uninherited_const_defined?(from_mod, const_name)
         return from_mod.const_get(const_name)
       elsif mod = autoload_module!(from_mod, const_name, qualified_name, path_suffix)
         return mod
       elsif (parent = from_mod.parent) && parent != from_mod &&
-            ! from_mod.parents.any? { |p| local_const_defined?(p, const_name) }
+            ! from_mod.parents.any? { |p| uninherited_const_defined?(p, const_name) }
         # If our parents do not have a constant named +const_name+ then we are free
         # to attempt to load upwards. If they do have such a constant, then this
         # const_missing must be due to from_mod::const_name, which should not
         # return constants from from_mod's parents.
         begin
@@ -477,45 +463,17 @@
     # Remove the constants that have been autoloaded, and those that have been
     # marked for unloading.
     def remove_unloadable_constants!
       autoloaded_constants.each { |const| remove_constant const }
       autoloaded_constants.clear
-      Reference.clear!
       explicitly_unloadable_constants.each { |const| remove_constant const }
     end
 
-    class Reference
-      @@constants = Hash.new { |h, k| h[k] = Inflector.constantize(k) }
-
-      attr_reader :name
-
-      def initialize(name)
-        @name = name.to_s
-        @@constants[@name] = name if name.respond_to?(:name)
-      end
-
-      def get
-        @@constants[@name]
-      end
-
-      def self.clear!
-        @@constants.clear
-      end
-    end
-
-    def ref(name)
-      references[name] ||= Reference.new(name)
-    end
-
-    def constantize(name)
-      ref(name).get
-    end
-
     # Determine if the given constant has been automatically loaded.
     def autoloaded?(desc)
       # No name => anonymous module.
-      return false if desc.is_a?(Module) && desc.anonymous?
+      return false if desc.is_a?(Module) && desc.name.blank?
       name = to_constant_name desc
       return false unless qualified_const_defined? name
       return autoloaded_constants.include?(name)
     end
 
@@ -545,30 +503,83 @@
     # If the provided block does not run to completion, and instead raises an
     # exception, any new constants are regarded as being only partially defined
     # and will be removed immediately.
     def new_constants_in(*descs)
       log_call(*descs)
-      watch_frames = constant_watch_stack.add_modules(descs)
 
+      # Build the watch frames. Each frame is a tuple of
+      #   [module_name_as_string, constants_defined_elsewhere]
+      watch_frames = descs.collect do |desc|
+        if desc.is_a? Module
+          mod_name = desc.name
+          initial_constants = desc.local_constant_names
+        elsif desc.is_a?(String) || desc.is_a?(Symbol)
+          mod_name = desc.to_s
+
+          # Handle the case where the module has yet to be defined.
+          initial_constants = if qualified_const_defined?(mod_name)
+            Inflector.constantize(mod_name).local_constant_names
+          else
+            []
+          end
+        else
+          raise Argument, "#{desc.inspect} does not describe a module!"
+        end
+
+        [mod_name, initial_constants]
+      end
+
+      constant_watch_stack_mutex.synchronize do
+        constant_watch_stack.concat watch_frames
+      end
+
       aborting = true
       begin
         yield # Now yield to the code that is to define new constants.
         aborting = false
       ensure
-        new_constants = constant_watch_stack.new_constants_for(watch_frames)
+        # Find the new constants.
+        new_constants = watch_frames.collect do |mod_name, prior_constants|
+          # Module still doesn't exist? Treat it as if it has no constants.
+          next [] unless qualified_const_defined?(mod_name)
 
+          mod = Inflector.constantize(mod_name)
+          next [] unless mod.is_a? Module
+          new_constants = mod.local_constant_names - prior_constants
+
+          # Make sure no other frames takes credit for these constants.
+          constant_watch_stack_mutex.synchronize do
+            constant_watch_stack.each do |frame_name, constants|
+              constants.concat new_constants if frame_name == mod_name
+            end
+          end
+
+          new_constants.collect do |suffix|
+            mod_name == "Object" ? suffix : "#{mod_name}::#{suffix}"
+          end
+        end.flatten
+
         log "New constants: #{new_constants * ', '}"
-        return new_constants unless aborting
 
-        log "Error during loading, removing partially loaded constants "
-        new_constants.each {|c| remove_constant(c) }.clear
+        if aborting
+          log "Error during loading, removing partially loaded constants "
+          new_constants.each { |name| remove_constant name }
+          new_constants.clear
+        end
       end
 
-      return []
+      return new_constants
     ensure
       # Remove the stack frames that we added.
-      watch_frames.each {|f| constant_watch_stack.delete(f) } if watch_frames.present?
+      if defined?(watch_frames) && ! watch_frames.blank?
+        frame_ids = watch_frames.collect { |frame| frame.object_id }
+        constant_watch_stack_mutex.synchronize do
+          constant_watch_stack.delete_if do |watch_frame|
+            frame_ids.include? watch_frame.object_id
+          end
+        end
+      end
     end
 
     class LoadingModule #:nodoc:
       # Old style environment.rb referenced this method directly.  Please note, it doesn't
       # actually *do* anything any more.
@@ -582,29 +593,31 @@
 
     # Convert the provided const desc to a qualified constant name (as a string).
     # A module, class, symbol, or string may be provided.
     def to_constant_name(desc) #:nodoc:
       name = case desc
-        when String then desc.sub(/^::/, '')
+        when String then desc.starts_with?('::') ? desc[2..-1] : desc
         when Symbol then desc.to_s
         when Module
-          desc.name.presence ||
-            raise(ArgumentError, "Anonymous modules have no name to be referenced by")
+          raise ArgumentError, "Anonymous modules have no name to be referenced by" if desc.name.blank?
+          desc.name
         else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}"
       end
     end
 
     def remove_constant(const) #:nodoc:
       return false unless qualified_const_defined? const
 
-      # Normalize ::Foo, Foo, Object::Foo, and ::Object::Foo to Object::Foo
-      names = const.to_s.sub(/^::(Object)?/, 'Object::').split("::")
-      to_remove = names.pop
-      parent = Inflector.constantize(names * '::')
+      const = $1 if /\A::(.*)\Z/ =~ const.to_s
+      names = const.to_s.split('::')
+      if names.size == 1 # It's under Object
+        parent = Object
+      else
+        parent = Inflector.constantize(names[0..-2] * '::')
+      end
 
       log "removing constant #{const}"
-      parent.instance_eval { remove_const to_remove }
-
+      parent.instance_eval { remove_const names.last }
       return true
     end
 
     protected
       def log_call(*args)