vendor/rails/railties/lib/rails/plugin/locator.rb

   1 module Rails
   2   class Plugin
   3
   4     # The Plugin::Locator class should be subclasses to provide custom plugin-finding
   5     # abilities to Rails (i.e. loading plugins from Gems, etc). Each subclass should implement
   6     # the <tt>located_plugins</tt> method, which return an array of Plugin objects that have been found.
   7     class Locator
   8       include Enumerable
   9
  10       attr_reader :initializer
  11
  12       def initialize(initializer)
  13         @initializer = initializer
  14       end
  15
  16       # This method should return all the plugins which this Plugin::Locator can find
  17       # These will then be used by the current Plugin::Loader, which is responsible for actually
  18       # loading the plugins themselves
  19       def plugins
  20         raise "The `plugins' method must be defined by concrete subclasses of #{self.class}"
  21       end
  22
  23       def each(&block)
  24         plugins.each(&block)
  25       end
  26
  27       def plugin_names
  28         plugins.map(&:name)
  29       end
  30     end
  31
  32     # The Rails::Plugin::FileSystemLocator will try to locate plugins by examining the directories
  33     # the the paths given in configuration.plugin_paths. Any plugins that can be found are returned
  34     # in a list.
  35     #
  36     # The criteria for a valid plugin in this case is found in Rails::Plugin#valid?, although
  37     # other subclasses of Rails::Plugin::Locator can of course use different conditions.
  38     class FileSystemLocator < Locator
  39
  40       # Returns all the plugins which can be loaded in the filesystem, under the paths given
  41       # by configuration.plugin_paths.
  42       def plugins
  43         initializer.configuration.plugin_paths.flatten.inject([]) do |plugins, path|
  44           plugins.concat locate_plugins_under(path)
  45           plugins
  46         end.flatten
  47       end
  48
  49       private
  50
  51         # Attempts to create a plugin from the given path. If the created plugin is valid?
  52         # (see Rails::Plugin#valid?) then the plugin instance is returned; otherwise nil.
  53         def create_plugin(path)
  54           plugin = Rails::Plugin.new(path)
  55           plugin.valid? ? plugin : nil
  56         end
  57
  58         # This starts at the base path looking for valid plugins (see Rails::Plugin#valid?).
  59         # Since plugins can be nested arbitrarily deep within an unspecified number of intermediary
  60         # directories, this method runs recursively until it finds a plugin directory, e.g.
  61         #
  62         #     locate_plugins_under('vendor/plugins/acts/acts_as_chunky_bacon')
  63         #     => <Rails::Plugin name: 'acts_as_chunky_bacon' ... >
  64         #
  65         def locate_plugins_under(base_path)
  66            Dir.glob(File.join(base_path, '*')).sort.inject([]) do |plugins, path|
  67             if plugin = create_plugin(path)
  68               plugins << plugin
  69             elsif File.directory?(path)
  70               plugins.concat locate_plugins_under(path)
  71             end
  72             plugins
  73           end
  74         end
  75     end
  76
  77     # The GemLocator scans all the loaded RubyGems, looking for gems with
  78     # a <tt>rails/init.rb</tt> file.
  79     class GemLocator < Locator
  80       def plugins
  81         gem_index = initializer.configuration.gems.inject({}) { |memo, gem| memo.update gem.specification => gem }
  82         specs     = gem_index.keys
  83         specs    += Gem.loaded_specs.values.select do |spec|
  84           spec.loaded_from && # prune stubs
  85             File.exist?(File.join(spec.full_gem_path, "rails", "init.rb"))
  86         end
  87         specs.compact!
  88
  89         require "rubygems/dependency_list"
  90
  91         deps = Gem::DependencyList.new
  92         deps.add(*specs) unless specs.empty?
  93
  94         deps.dependency_order.collect do |spec|
  95           Rails::GemPlugin.new(spec, gem_index[spec])
  96         end
  97       end
  98     end
  99   end
 100 end