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require 'rails/railtie'
require 'active_support/core_ext/module/delegation'
require 'pathname'
require 'rbconfig'
module Rails
# Rails::Engine allows you to wrap a specific Rails application and share it accross
# different applications. Since Rails 3.0, every Rails::Application is nothing
# more than an Engine, allowing you to share it very easily.
#
# Any Rails::Engine is also a Rails::Railtie, so the same methods (like rake_tasks and
# generators) and configuration available in the latter can also be used in the former.
#
# == Creating an Engine
#
# In Rails versions before to 3.0, your gems automatically behaved as Engine, however
# this coupled Rails to Rubygems. Since Rails 3.0, if you want a gem to automatically
# behave as Engine, you have to specify an Engine for it somewhere inside your plugin
# lib folder (similar with how we spceify a Railtie):
#
# # lib/my_engine.rb
# module MyEngine
# class Engine < Rails::Engine
# end
# end
#
# Then ensure that this file is loaded at the top of your config/application.rb (or in
# your Gemfile) and it will automatically load models, controllers and helpers
# inside app, load routes at "config/routes.rb", load locales at "config/locales/*",
# load tasks at "lib/tasks/*".
#
# == Configuration
#
# Besides the Railtie configuration which is shared across the application, in a
# Rails::Engine you can access load_paths, eager_load_paths and load_once_paths,
# which differently from a Railtie, are scoped to the current Engine.
#
# Example:
#
# class MyEngine < Rails::Engine
# # Add a load path for this specific Engine
# config.load_paths << File.expand_path("../lib/some/path", __FILE__)
#
# initializer "my_engine.add_middleware" do |app|
# app.middleware.use MyEngine::Middleware
# end
# end
#
# == Paths
#
# Since Rails 3.0, both your Application and Engines do not have hardcoded paths.
# This means that you are not required to place your controllers at "app/controllers",
# but in any place which you find convenient.
#
# For example, let's suppose you want to lay your controllers at lib/controllers, all
# you need to do is:
#
# class MyEngine < Rails::Engine
# paths.app.controllers = "lib/controllers"
# end
#
# You can also have your controllers being loaded from both "app/controllers" and
# "lib/controllers":
#
# class MyEngine < Rails::Engine
# paths.app.controllers << "lib/controllers"
# end
#
# The available paths in an Engine are:
#
# class MyEngine < Rails::Engine
# paths.app = "app"
# paths.app.controllers = "app/controllers"
# paths.app.helpers = "app/helpers"
# paths.app.models = "app/models"
# paths.app.views = "app/views"
# paths.lib = "lib"
# paths.lib.tasks = "lib/tasks"
# paths.config = "config"
# paths.config.initializers = "config/initializers"
# paths.config.locales = "config/locales"
# paths.config.routes = "config/routes.rb"
# end
#
# Your Application class adds a couple more paths to this set. And as in your Application,
# all folders under "app" are automatically added to the load path. So if you have
# "app/observers", it's added by default.
#
class Engine < Railtie
autoload :Configurable, "rails/engine/configurable"
autoload :Configuration, "rails/engine/configuration"
class << self
attr_accessor :called_from
# TODO Remove this. It's deprecated.
alias :engine_name :railtie_name
def inherited(base)
unless base.abstract_railtie?
base.called_from = begin
# Remove the line number from backtraces making sure we don't leave anything behind
call_stack = caller.map { |p| p.split(':')[0..-2].join(':') }
File.dirname(call_stack.detect { |p| p !~ %r[railties[\w\-\.]*/lib/rails|rack[\w\-\.]*/lib/rack] })
end
end
super
end
def find_root_with_flag(flag, default=nil)
root_path = self.called_from
while root_path && File.directory?(root_path) && !File.exist?("#{root_path}/#{flag}")
parent = File.dirname(root_path)
root_path = parent != root_path && parent
end
root = File.exist?("#{root_path}/#{flag}") ? root_path : default
raise "Could not find root path for #{self}" unless root
Config::CONFIG['host_os'] =~ /mswin|mingw/ ?
Pathname.new(root).expand_path : Pathname.new(root).realpath
end
end
delegate :paths, :root, :to => :config
def load_tasks
super
config.paths.lib.tasks.to_a.sort.each { |ext| load(ext) }
end
def eager_load!
config.eager_load_paths.each do |load_path|
matcher = /\A#{Regexp.escape(load_path)}\/(.*)\.rb\Z/
Dir.glob("#{load_path}/**/*.rb").sort.each do |file|
require_dependency file.sub(matcher, '\1')
end
end
end
# Add configured load paths to ruby load paths and remove duplicates.
initializer :set_load_path, :before => :bootstrap_hook do
config.load_paths.reverse_each do |path|
$LOAD_PATH.unshift(path) if File.directory?(path)
end
$LOAD_PATH.uniq!
end
# Set the paths from which Rails will automatically load source files,
# and the load_once paths.
#
# This needs to be an initializer, since it needs to run once
# per engine and get the engine as a block parameter
initializer :set_autoload_paths, :before => :bootstrap_hook do |app|
ActiveSupport::Dependencies.load_paths.unshift(*config.load_paths)
if reloadable?(app)
ActiveSupport::Dependencies.load_once_paths.unshift(*config.load_once_paths)
else
ActiveSupport::Dependencies.load_once_paths.unshift(*config.load_paths)
end
# Freeze so future modifications will fail rather than do nothing mysteriously
config.load_paths.freeze
config.load_once_paths.freeze
end
initializer :add_routing_paths do |app|
paths.config.routes.to_a.each do |route|
app.routes_reloader.paths.unshift(route) if File.exists?(route)
end
end
# DEPRECATED: Remove in 3.1
initializer :add_routing_namespaces do |app|
paths.app.controllers.to_a.each do |load_path|
load_path = File.expand_path(load_path)
Dir["#{load_path}/*/**/*_controller.rb"].collect do |path|
namespace = File.dirname(path).sub(/#{Regexp.escape(load_path)}\/?/, '')
app.routes.controller_namespaces << namespace unless namespace.empty?
end
end
end
# I18n load paths are a special case since the ones added
# later have higher priority.
initializer :add_locales do
config.i18n.railties_load_path.concat(paths.config.locales.to_a)
end
initializer :add_view_paths do
views = paths.app.views.to_a
ActiveSupport.on_load(:action_controller) do
prepend_view_path(views)
end
ActiveSupport.on_load(:action_mailer) do
prepend_view_path(views)
end
end
initializer :load_config_initializers do
paths.config.initializers.to_a.sort.each do |initializer|
load(initializer)
end
end
initializer :engines_blank_point do
# We need this initializer so all extra initializers added in engines are
# consistently executed after all the initializers above across all engines.
end
protected
def reloadable?(app)
app.config.reload_engines
end
end
end
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