Merge bundler to standard libraries.

rubygems 2.7.x depends bundler-1.15.x. This is preparation for
  rubygems and bundler migration.

  * lib/bundler.rb, lib/bundler/*: files of bundler-1.15.4
  * spec/bundler/*: rspec examples of bundler-1.15.4. I applied patches.
    * https://github.com/bundler/bundler/pull/6007
    * Exclude not working examples on ruby repository.
    * Fake ruby interpriter instead of installed ruby.
  * Makefile.in: Added test task named `test-bundler`. This task is only
    working macOS/linux yet. I'm going to support Windows environment later.
  * tool/sync_default_gems.rb: Added sync task for bundler.

  [Feature #12733][ruby-core:77172]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59779 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/bundler/plugin/index.rb

@@ -0,0 +1,157 @@
+# frozen_string_literal: true
+
+module Bundler
+  # Manages which plugins are installed and their sources. This also is supposed to map
+  # which plugin does what (currently the features are not implemented so this class is
+  # now a stub class).
+  module Plugin
+    class Index
+      class CommandConflict < PluginError
+        def initialize(plugin, commands)
+          msg = "Command(s) `#{commands.join("`, `")}` declared by #{plugin} are already registered."
+          super msg
+        end
+      end
+
+      class SourceConflict < PluginError
+        def initialize(plugin, sources)
+          msg = "Source(s) `#{sources.join("`, `")}` declared by #{plugin} are already registered."
+          super msg
+        end
+      end
+
+      attr_reader :commands
+
+      def initialize
+        @plugin_paths = {}
+        @commands = {}
+        @sources = {}
+        @hooks = {}
+        @load_paths = {}
+
+        load_index(global_index_file, true)
+        load_index(local_index_file) if SharedHelpers.in_bundle?
+      end
+
+      # This function is to be called when a new plugin is installed. This
+      # function shall add the functions of the plugin to existing maps and also
+      # the name to source location.
+      #
+      # @param [String] name of the plugin to be registered
+      # @param [String] path where the plugin is installed
+      # @param [Array<String>] load_paths for the plugin
+      # @param [Array<String>] commands that are handled by the plugin
+      # @param [Array<String>] sources that are handled by the plugin
+      def register_plugin(name, path, load_paths, commands, sources, hooks)
+        old_commands = @commands.dup
+
+        common = commands & @commands.keys
+        raise CommandConflict.new(name, common) unless common.empty?
+        commands.each {|c| @commands[c] = name }
+
+        common = sources & @sources.keys
+        raise SourceConflict.new(name, common) unless common.empty?
+        sources.each {|k| @sources[k] = name }
+
+        hooks.each {|e| (@hooks[e] ||= []) << name }
+
+        @plugin_paths[name] = path
+        @load_paths[name] = load_paths
+        save_index
+      rescue
+        @commands = old_commands
+        raise
+      end
+
+      # Path of default index file
+      def index_file
+        Plugin.root.join("index")
+      end
+
+      # Path where the global index file is stored
+      def global_index_file
+        Plugin.global_root.join("index")
+      end
+
+      # Path where the local index file is stored
+      def local_index_file
+        Plugin.local_root.join("index")
+      end
+
+      def plugin_path(name)
+        Pathname.new @plugin_paths[name]
+      end
+
+      def load_paths(name)
+        @load_paths[name]
+      end
+
+      # Fetch the name of plugin handling the command
+      def command_plugin(command)
+        @commands[command]
+      end
+
+      def installed?(name)
+        @plugin_paths[name]
+      end
+
+      def source?(source)
+        @sources.key? source
+      end
+
+      def source_plugin(name)
+        @sources[name]
+      end
+
+      # Returns the list of plugin names handling the passed event
+      def hook_plugins(event)
+        @hooks[event] || []
+      end
+
+    private
+
+      # Reads the index file from the directory and initializes the instance
+      # variables.
+      #
+      # It skips the sources if the second param is true
+      # @param [Pathname] index file path
+      # @param [Boolean] is the index file global index
+      def load_index(index_file, global = false)
+        SharedHelpers.filesystem_access(index_file, :read) do |index_f|
+          valid_file = index_f && index_f.exist? && !index_f.size.zero?
+          break unless valid_file
+
+          data = index_f.read
+
+          require "bundler/yaml_serializer"
+          index = YAMLSerializer.load(data)
+
+          @commands.merge!(index["commands"])
+          @hooks.merge!(index["hooks"])
+          @load_paths.merge!(index["load_paths"])
+          @plugin_paths.merge!(index["plugin_paths"])
+          @sources.merge!(index["sources"]) unless global
+        end
+      end
+
+      # Should be called when any of the instance variables change. Stores the
+      # instance variables in YAML format. (The instance variables are supposed
+      # to be only String key value pairs)
+      def save_index
+        index = {
+          "commands"     => @commands,
+          "hooks"        => @hooks,
+          "load_paths"   => @load_paths,
+          "plugin_paths" => @plugin_paths,
+          "sources"      => @sources,
+        }
+
+        require "bundler/yaml_serializer"
+        SharedHelpers.filesystem_access(index_file) do |index_f|
+          FileUtils.mkdir_p(index_f.dirname)
+          File.open(index_f, "w") {|f| f.puts YAMLSerializer.dump(index) }
+        end
+      end
+    end
+  end
+end