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require 'set'
require 'thread'
require 'thread_safe'
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/module/qualified_const'
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'
module ActiveSupport #:nodoc:
module Dependencies #:nodoc:
extend self
# Should we turn on Ruby warnings on the first load of dependent files?
mattr_accessor :warnings_on_first_load
self.warnings_on_first_load = false
# All files ever loaded.
mattr_accessor :history
self.history = Set.new
# All files currently loaded.
mattr_accessor :loaded
self.loaded = Set.new
# Should we load files or require them?
mattr_accessor :mechanism
self.mechanism = ENV['NO_RELOAD'] ? :require : :load
# The set of directories from which we may automatically load files. Files
# under these directories will be reloaded on each request in development mode,
# unless the directory also appears in autoload_once_paths.
mattr_accessor :autoload_paths
self.autoload_paths = []
# The set of directories from which automatically loaded constants are loaded
# only once. All directories in this set must also be present in +autoload_paths+.
mattr_accessor :autoload_once_paths
self.autoload_once_paths = []
# 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 = []
# 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 = []
# The logger is used for generating information on the action run-time
# (including benchmarking) if available. Can be set to nil for no logging.
# Compatible with both Ruby's own Logger and Log4r loggers.
mattr_accessor :logger
# Set to +true+ to enable logging of const_missing and file loads.
mattr_accessor :log_activity
self.log_activity = false
# The WatchStack keeps a stack of the modules being watched as files are
# loaded. If a file in the process of being loaded (parent.rb) triggers the
# load of another file (child.rb) the stack will ensure that child.rb
# handles the new constants.
#
# If child.rb is being autoloaded, its constants will be added to
# autoloaded_constants. If it was being `require`d, they will be discarded.
#
# This is handled by walking back up the watch stack and adding the constants
# found by child.rb to the list of original constants in parent.rb.
class WatchStack
include Enumerable
# @watching is a stack of lists of constants being watched. For instance,
# if parent.rb is autoloaded, the stack will look like [[Object]]. If
# parent.rb then requires namespace/child.rb, the stack will look like
# [[Object], [Namespace]].
def initialize
@watching = []
@stack = Hash.new { |h,k| h[k] = [] }
end
def each(&block)
@stack.each(&block)
end
def watching?
!@watching.empty?
end
# Returns a list of new constants found since the last call to
# <tt>watch_namespaces</tt>.
def new_constants
constants = []
# Grab the list of namespaces that we're looking for new constants under
@watching.last.each do |namespace|
# Retrieve the constants that were present under the namespace when watch_namespaces
# was originally called
original_constants = @stack[namespace].last
mod = Inflector.constantize(namespace) if Dependencies.qualified_const_defined?(namespace)
next unless mod.is_a?(Module)
# Get a list of the constants that were added
new_constants = mod.local_constants - original_constants
# self[namespace] returns an Array of the constants that are being evaluated
# for that namespace. For instance, if parent.rb requires child.rb, the first
# element of self[Object] will be an Array of the constants that were present
# before parent.rb was required. The second element will be an Array of the
# constants that were present before child.rb was required.
@stack[namespace].each do |namespace_constants|
namespace_constants.concat(new_constants)
end
# Normalize the list of new constants, and add them to the list we will return
new_constants.each do |suffix|
constants << ([namespace, suffix] - ["Object"]).join("::")
end
end
constants
ensure
# A call to new_constants is always called after a call to watch_namespaces
pop_modules(@watching.pop)
end
# Add a set of modules to the watch stack, remembering the initial
# constants.
def watch_namespaces(namespaces)
@watching << namespaces.map do |namespace|
module_name = Dependencies.to_constant_name(namespace)
original_constants = Dependencies.qualified_const_defined?(module_name) ?
Inflector.constantize(module_name).local_constants : []
@stack[module_name] << original_constants
module_name
end
end
private
def pop_modules(modules)
modules.each { |mod| @stack[mod].pop }
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
# Module includes this module.
module ModuleConstMissing #:nodoc:
def self.append_features(base)
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)
end
super
end
def self.exclude_from(base)
base.class_eval do
define_method :const_missing, @_const_missing
@_const_missing = nil
end
end
def const_missing(const_name)
# The interpreter does not pass nesting information, and in the
# case of anonymous modules we cannot even make the trade-off of
# assuming their name reflects the nesting. Resort to Object as
# the only meaningful guess we can make.
from_mod = anonymous? ? ::Object : self
Dependencies.load_missing_constant(from_mod, const_name)
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)) }
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, message)
end
def load_dependency(file)
if Dependencies.load? && ActiveSupport::Dependencies.constant_watch_stack.watching?
Dependencies.new_constants_in(Object) { yield }
else
yield
end
rescue Exception => exception # errors from loading file
exception.blame_file! file if exception.respond_to? :blame_file!
raise
end
def load(file, wrap = false)
result = false
load_dependency(file) { result = super }
result
end
def require(file)
result = false
load_dependency(file) { result = super }
result
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;
# each constant will be removed for every subsequent clear, as opposed to
# for the first clear.
#
# The provided constant descriptor may be a (non-anonymous) module or class,
# or a qualified constant name as a string or symbol.
#
# Returns +true+ if the constant was not previously marked for unloading,
# +false+ otherwise.
def unloadable(const_desc)
Dependencies.mark_for_unload const_desc
end
end
# Exception file-blaming.
module Blamable #:nodoc:
def blame_file!(file)
(@blamed_files ||= []).unshift file
end
def blamed_files
@blamed_files ||= []
end
def describe_blame
return nil if blamed_files.empty?
"This error occurred while loading the following files:\n #{blamed_files.join "\n "}"
end
def copy_blame!(exc)
@blamed_files = exc.blamed_files.clone
self
end
end
def hook!
Object.class_eval { include Loadable }
Module.class_eval { include ModuleConstMissing }
Exception.class_eval { include Blamable }
end
def unhook!
ModuleConstMissing.exclude_from(Module)
Loadable.exclude_from(Object)
end
def load?
mechanism == :load
end
def depend_on(file_name, message = "No such file to load -- %s.rb")
path = search_for_file(file_name)
require_or_load(path || file_name)
rescue LoadError => load_error
if file_name = load_error.message[/ -- (.*?)(\.rb)?$/, 1]
load_error.message.replace(message % file_name)
load_error.copy_blame!(load_error)
end
raise
end
def clear
log_call
loaded.clear
remove_unloadable_constants!
end
def require_or_load(file_name, const_path = nil)
log_call file_name, const_path
file_name = $` if file_name =~ /\.rb\z/
expanded = File.expand_path(file_name)
return if loaded.include?(expanded)
# Record that we've seen this file *before* loading it to avoid an
# infinite loop with mutual dependencies.
loaded << expanded
begin
if load?
log "loading #{file_name}"
# Enable warnings if this file has not been loaded before and
# warnings_on_first_load is set.
load_args = ["#{file_name}.rb"]
load_args << const_path unless const_path.nil?
if !warnings_on_first_load or history.include?(expanded)
result = load_file(*load_args)
else
enable_warnings { result = load_file(*load_args) }
end
else
log "requiring #{file_name}"
result = require file_name
end
rescue Exception
loaded.delete expanded
raise
end
# Record history *after* loading so first load gets warnings.
history << expanded
result
end
# Is the provided constant path defined?
def qualified_const_defined?(path)
Object.qualified_const_defined?(path.sub(/^::/, ''), false)
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 = autoload_paths)
path = $` if path =~ /\.rb\z/
expanded_path = File.expand_path(path)
paths = []
bases.each do |root|
expanded_root = File.expand_path(root)
next unless %r{\A#{Regexp.escape(expanded_root)}(/|\\)} =~ expanded_path
nesting = expanded_path[(expanded_root.size)..-1]
nesting = nesting[1..-1] if nesting && nesting[0] == ?/
next if nesting.blank?
paths << nesting.camelize
end
paths.uniq!
paths
end
# Search for a file in autoload_paths matching the provided suffix.
def search_for_file(path_suffix)
path_suffix = path_suffix.sub(/(\.rb)?$/, ".rb")
autoload_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 ;-)
end
# Does the provided path_suffix correspond to an autoloadable module?
# Instead of returning a boolean, the autoload base for this module is
# returned.
def autoloadable_module?(path_suffix)
autoload_paths.each do |load_path|
return load_path if File.directory? File.join(load_path, path_suffix)
end
nil
end
def load_once_path?(path)
# to_s works around a ruby1.9 issue where #starts_with?(Pathname) will always return false
autoload_once_paths.any? { |base| path.starts_with? base.to_s }
end
# Attempt to autoload the provided module name by searching for a directory
# matching the expected path suffix. If found, the module is created and
# assigned to +into+'s constants with the name +const_name+. Provided that
# the directory was loaded from a reloadable base path, it is added to the
# set of constants that are to be unloaded.
def autoload_module!(into, const_name, qualified_name, path_suffix)
return nil unless base_path = autoloadable_module?(path_suffix)
mod = Module.new
into.const_set const_name, mod
autoloaded_constants << qualified_name unless autoload_once_paths.include?(base_path)
mod
end
# Load the file at the provided path. +const_paths+ is a set of qualified
# constant names. When loading the file, Dependencies will watch for the
# addition of these constants. Each that is defined will be marked as
# autoloaded, and will be removed when Dependencies.clear is next called.
#
# If the second parameter is left off, then Dependencies will construct a
# set of names that the file at +path+ may define. See
# +loadable_constants_for_path+ for more details.
def load_file(path, const_paths = loadable_constants_for_path(path))
log_call path, const_paths
const_paths = [const_paths].compact unless const_paths.is_a? Array
parent_paths = const_paths.collect { |const_path| const_path[/.*(?=::)/] || ::Object }
result = nil
newly_defined_paths = new_constants_in(*parent_paths) do
result = Kernel.load 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?
result
end
# Returns 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}"
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
unless qualified_const_defined?(from_mod.name) && Inflector.constantize(from_mod.name).equal?(from_mod)
raise ArgumentError, "A copy of #{from_mod} has been removed from the module tree but is still active!"
end
raise NameError, "#{from_mod} is not missing constant #{const_name}!" if from_mod.const_defined?(const_name, false)
qualified_name = qualified_name_for from_mod, const_name
path_suffix = qualified_name.underscore
file_path = search_for_file(path_suffix)
if file_path
expanded = File.expand_path(file_path)
expanded.sub!(/\.rb\z/, '')
if loaded.include?(expanded)
raise "Circular dependency detected while autoloading constant #{qualified_name}"
else
require_or_load(expanded)
raise LoadError, "Unable to autoload constant #{qualified_name}, expected #{file_path} to define it" unless from_mod.const_defined?(const_name, false)
return from_mod.const_get(const_name)
end
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| p.const_defined?(const_name, false) }
# 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
# Since Ruby does not pass the nesting at the point the unknown
# constant triggered the callback we cannot fully emulate constant
# name lookup and need to make a trade-off: we are going to assume
# that the nesting in the body of Foo::Bar is [Foo::Bar, Foo] even
# though it might not be. Counterexamples are
#
# class Foo::Bar
# Module.nesting # => [Foo::Bar]
# end
#
# or
#
# module M::N
# module S::T
# Module.nesting # => [S::T, M::N]
# end
# end
#
# for example.
return parent.const_missing(const_name)
rescue NameError => e
raise unless e.missing_name? qualified_name_for(parent, const_name)
end
end
raise NameError,
"uninitialized constant #{qualified_name}",
caller.reject { |l| l.starts_with? __FILE__ }
end
# Remove the constants that have been autoloaded, and those that have been
# marked for unloading. Before each constant is removed a callback is sent
# to its class/module if it implements +before_remove_const+.
#
# The callback implementation should be restricted to cleaning up caches, etc.
# as the environment will be in an inconsistent state, e.g. other constants
# may have already been unloaded and not accessible.
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 ClassCache
def initialize
@store = ThreadSafe::Cache.new
end
def empty?
@store.empty?
end
def key?(key)
@store.key?(key)
end
def get(key)
key = key.name if key.respond_to?(:name)
@store[key] ||= Inflector.constantize(key)
end
alias :[] :get
def safe_get(key)
key = key.name if key.respond_to?(:name)
@store[key] ||= Inflector.safe_constantize(key)
end
def store(klass)
return self unless klass.respond_to?(:name)
raise(ArgumentError, 'anonymous classes cannot be cached') if klass.name.empty?
@store[klass.name] = klass
self
end
def clear!
@store.clear
end
end
Reference = ClassCache.new
# Store a reference to a class +klass+.
def reference(klass)
Reference.store klass
end
# Get the reference for class named +name+.
# Raises an exception if referenced class does not exist.
def constantize(name)
Reference.get(name)
end
# Get the reference for class named +name+ if one exists.
# Otherwise returns +nil+.
def safe_constantize(name)
Reference.safe_get(name)
end
# Determine if the given constant has been automatically loaded.
def autoloaded?(desc)
return false if desc.is_a?(Module) && desc.anonymous?
name = to_constant_name desc
return false unless qualified_const_defined? name
return autoloaded_constants.include?(name)
end
# Will the provided constant descriptor be unloaded?
def will_unload?(const_desc)
autoloaded?(const_desc) ||
explicitly_unloadable_constants.include?(to_constant_name(const_desc))
end
# Mark the provided constant name for unloading. This constant will be
# unloaded on each request, not just the next one.
def mark_for_unload(const_desc)
name = to_constant_name const_desc
if explicitly_unloadable_constants.include? name
false
else
explicitly_unloadable_constants << name
true
end
end
# Run the provided block and detect the new constants that were loaded during
# its execution. Constants may only be regarded as 'new' once -- so if the
# block calls +new_constants_in+ again, then the constants defined within the
# inner call will not be reported in this one.
#
# 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)
constant_watch_stack.watch_namespaces(descs)
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
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
end
[]
end
# 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:
case desc
when String then desc.sub(/^::/, '')
when Symbol then desc.to_s
when Module
desc.name ||
raise(ArgumentError, "Anonymous modules have no name to be referenced by")
else raise TypeError, "Not a valid constant descriptor: #{desc.inspect}"
end
end
def remove_constant(const) #:nodoc:
# Normalize ::Foo, ::Object::Foo, Object::Foo, Object::Object::Foo, etc. as Foo.
normalized = const.to_s.sub(/\A::/, '')
normalized.sub!(/\A(Object::)+/, '')
constants = normalized.split('::')
to_remove = constants.pop
if constants.empty?
parent = Object
else
# This method is robust to non-reachable constants.
#
# Non-reachable constants may be passed if some of the parents were
# autoloaded and already removed. It is easier to do a sanity check
# here than require the caller to be clever. We check the parent
# rather than the very const argument because we do not want to
# trigger Kernel#autoloads, see the comment below.
parent_name = constants.join('::')
return unless qualified_const_defined?(parent_name)
parent = constantize(parent_name)
end
log "removing constant #{const}"
# In an autoloaded user.rb like this
#
# autoload :Foo, 'foo'
#
# class User < ActiveRecord::Base
# end
#
# we correctly register "Foo" as being autoloaded. But if the app does
# not use the "Foo" constant we need to be careful not to trigger
# loading "foo.rb" ourselves. While #const_defined? and #const_get? do
# require the file, #autoload? and #remove_const don't.
#
# We are going to remove the constant nonetheless ---which exists as
# far as Ruby is concerned--- because if the user removes the macro
# call from a class or module that were not autoloaded, as in the
# example above with Object, accessing to that constant must err.
unless parent.autoload?(to_remove)
begin
constantized = parent.const_get(to_remove, false)
rescue NameError
log "the constant #{const} is not reachable anymore, skipping"
return
else
constantized.before_remove_const if constantized.respond_to?(:before_remove_const)
end
end
begin
parent.instance_eval { remove_const to_remove }
rescue NameError
log "the constant #{const} is not reachable anymore, skipping"
end
end
protected
def log_call(*args)
if log_activity?
arg_str = args.collect { |arg| arg.inspect } * ', '
/in `([a-z_\?\!]+)'/ =~ caller(1).first
selector = $1 || '<unknown>'
log "called #{selector}(#{arg_str})"
end
end
def log(msg)
logger.debug "Dependencies: #{msg}" if log_activity?
end
def log_activity?
logger && log_activity
end
end
end
ActiveSupport::Dependencies.hook!
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