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require 'set'
require File.dirname(__FILE__) + '/core_ext/module/attribute_accessors'
require File.dirname(__FILE__) + '/core_ext/load_error'
require File.dirname(__FILE__) + '/core_ext/kernel'
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 = :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 load_once_paths.
mattr_accessor :load_paths
self.load_paths = []
# The set of directories from which automatically loaded constants are loaded
# only once. All directories in this set must also be present in +load_paths+.
mattr_accessor :load_once_paths
self.load_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 = []
# Set to true to enable logging of const_missing and file loads
mattr_accessor :log_activity
self.log_activity = false
# An internal stack used to record which constants are loaded by any block.
mattr_accessor :constant_watch_stack
self.constant_watch_stack = []
def load?
mechanism == :load
end
def depend_on(file_name, swallow_load_errors = false)
path = search_for_file(file_name)
require_or_load(path || file_name)
rescue LoadError
raise unless swallow_load_errors
end
def associate_with(file_name)
depend_on(file_name, true)
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 = $1 if file_name =~ /^(.*)\.rb$/
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
if load?
log "loading #{file_name}"
begin
# Enable warnings iff 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
rescue Exception
loaded.delete expanded
raise
end
else
log "requiring #{file_name}"
result = require file_name
end
# Record history *after* loading so first load gets warnings.
history << expanded
return result
end
# Is the provided constant path defined?
def qualified_const_defined?(path)
raise NameError, "#{path.inspect} is not a valid constant name!" unless
/^(::)?([A-Z]\w*)(::[A-Z]\w*)*$/ =~ path
names = path.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 mod.const_defined? name
mod.const_get name
end
return true
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)
path = $1 if path =~ /\A(.*)\.rb\Z/
expanded_path = File.expand_path(path)
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.camelize,
# Special case: application.rb might define ApplicationControlller.
('ApplicationController' if nesting == 'application')
]
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 + '.rb' unless path_suffix.ends_with? '.rb'
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 ;-)
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)
load_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)
load_once_paths.any? { |base| path.starts_with? base }
end
# Attempt to autoload the provided module name by searching for a directory
# matching the expect 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 load_once_paths.include?(base_path)
return 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| /(.*)::[^:]+\Z/ =~ const_path ? $1 : :Object }
result = nil
newly_defined_paths = new_constants_in(*parent_paths) do
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?
return result
end
# Return the constant path for the provided parent and constant name.
def qualified_name_for(mod, name)
mod_name = to_constant_name mod
(%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 laod 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
# If we have an anonymous module, all we can do is attempt to load from Object.
from_mod = Object if from_mod.name.empty?
unless qualified_const_defined?(from_mod.name) && from_mod.name.constantize.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 from_mod.const_defined?(const_name)
qualified_name = qualified_name_for from_mod, const_name
path_suffix = qualified_name.underscore
name_error = NameError.new("uninitialized constant #{qualified_name}")
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 from_mod.const_defined?(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| p.const_defined?(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
return parent.const_missing(const_name)
rescue NameError => e
raise unless e.missing_name? qualified_name_for(parent, const_name)
raise name_error
end
else
raise name_error
end
end
# 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
explicitly_unloadable_constants.each { |const| remove_constant const }
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.name.blank?
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?(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
return false
else
explicitly_unloadable_constants << name
return 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)
# 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_constants
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)
mod_name.constantize.local_constants
else
[]
end
else
raise Argument, "#{desc.inspect} does not describe a module!"
end
[mod_name, initial_constants]
end
constant_watch_stack.concat watch_frames
aborting = true
begin
yield # Now yield to the code that is to define new constants.
aborting = false
ensure
# 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 = mod_name.constantize
next [] unless mod.is_a? Module
new_constants = mod.local_constants - prior_constants
# Make sure no other frames takes credit for these constants.
constant_watch_stack.each do |frame_name, constants|
constants.concat new_constants if frame_name == mod_name
end
new_constants.collect do |suffix|
mod_name == "Object" ? suffix : "#{mod_name}::#{suffix}"
end
end.flatten
log "New constants: #{new_constants * ', '}"
if aborting
log "Error during loading, removing partially loaded constants "
new_constants.each { |name| remove_constant name }
new_constants.clear
end
end
return new_constants
ensure
# Remove the stack frames that we added.
if defined?(watch_frames) && ! watch_frames.empty?
frame_ids = watch_frames.collect(&:object_id)
constant_watch_stack.delete_if do |watch_frame|
frame_ids.include? watch_frame.object_id
end
end
end
class LoadingModule #:nodoc:
# Old style environment.rb referenced this method directly. Please note, it doesn't
# actualy *do* anything any more.
def self.root(*args)
if defined?(RAILS_DEFAULT_LOGGER)
RAILS_DEFAULT_LOGGER.warn "Your environment.rb uses the old syntax, it may not continue to work in future releases."
RAILS_DEFAULT_LOGGER.warn "For upgrade instructions please see: http://manuals.rubyonrails.com/read/book/19"
end
end
end
protected
# 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)
name = case desc
when String then desc.starts_with?('::') ? desc[2..-1] : desc
when Symbol then desc.to_s
when Module
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)
return false unless qualified_const_defined? const
const = $1 if /\A::(.*)\Z/ =~ const.to_s
names = const.split('::')
if names.size == 1 # It's under Object
parent = Object
else
parent = (names[0..-2] * '::').constantize
end
log "removing constant #{const}"
parent.send :remove_const, names.last
return true
end
def log_call(*args)
arg_str = args.collect(&:inspect) * ', '
/in `([a-z_\?\!]+)'/ =~ caller(1).first
selector = $1 || '<unknown>'
log "called #{selector}(#{arg_str})"
end
def log(msg)
if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER && log_activity
RAILS_DEFAULT_LOGGER.debug "Dependencies: #{msg}"
end
end
end
Object.send(:define_method, :require_or_load) { |file_name| Dependencies.require_or_load(file_name) } unless Object.respond_to?(:require_or_load)
Object.send(:define_method, :require_dependency) { |file_name| Dependencies.depend_on(file_name) } unless Object.respond_to?(:require_dependency)
Object.send(:define_method, :require_association) { |file_name| Dependencies.associate_with(file_name) } unless Object.respond_to?(:require_association)
class Module #:nodoc:
# Rename the original handler so we can chain it to the new one
alias :rails_original_const_missing :const_missing
# Use const_missing to autoload associations so we don't have to
# require_association when using single-table inheritance.
def const_missing(class_id)
Dependencies.load_missing_constant self, class_id
end
def unloadable(const_desc = self)
super(const_desc)
end
end
class Class
def const_missing(class_id)
if [Object, Kernel].include?(self) || parent == self
super
else
begin
begin
Dependencies.load_missing_constant self, class_id
rescue NameError
parent.send :const_missing, class_id
end
rescue NameError => e
# Make sure that the name we are missing is the one that caused the error
parent_qualified_name = Dependencies.qualified_name_for parent, class_id
raise unless e.missing_name? parent_qualified_name
qualified_name = Dependencies.qualified_name_for self, class_id
raise NameError.new("uninitialized constant #{qualified_name}").copy_blame!(e)
end
end
end
end
class Object #:nodoc:
alias_method :load_without_new_constant_marking, :load
def load(file, *extras)
Dependencies.new_constants_in(Object) { super(file, *extras) }
rescue Exception => exception # errors from loading file
exception.blame_file! file
raise
end
def require(file, *extras)
Dependencies.new_constants_in(Object) { super(file, *extras) }
rescue Exception => exception # errors from required file
exception.blame_file! file
raise
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
# Add file-blaming to exceptions
class Exception #: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
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