Add a Guard::API module that Guard plugins should include

This is a first step toward a sanitized plugin architecture:

Mixin instead of inheritance.

Signed-off-by: Rémy Coutable <remy@rymai.me>

lib/guard/api.rb

@@ -0,0 +1,279 @@
+require "guard"
+require "guard/internals/groups"
+
+module Guard
+  module API
+    TEMPLATE_FORMAT = "%s/lib/guard/%s/templates/Guardfile"
+
+    require "guard/ui"
+
+    def self.included(base)
+      base.extend(ClassMethods)
+      base.class_eval do
+        attr_accessor :group, :watchers, :callbacks, :options
+      end
+    end
+
+    module ClassMethods
+      # Get all callbacks registered for all Guard plugins present in the
+      # Guardfile.
+      #
+      def callbacks
+        @callbacks ||= Hash.new { |hash, key| hash[key] = [] }
+      end
+
+      # Add a callback.
+      #
+      # @param [Block] listener the listener to notify
+      # @param [Guard::Plugin] guard_plugin the Guard plugin to add the callback
+      # @param [Array<Symbol>] events the events to register
+      #
+      def add_callback(listener, guard_plugin, events)
+        Array(events).each do |event|
+          callbacks[[guard_plugin, event]] << listener
+        end
+      end
+
+      # Notify a callback.
+      #
+      # @param [Guard::Plugin] guard_plugin the Guard plugin to add the callback
+      # @param [Symbol] event the event to trigger
+      # @param [Array] args the arguments for the listener
+      #
+      def notify(guard_plugin, event, *args)
+        callbacks[[guard_plugin, event]].each do |listener|
+          listener.call(guard_plugin, event, *args)
+        end
+      end
+
+      # Reset all callbacks.
+      #
+      # TODO: remove (not used anywhere)
+      def reset_callbacks!
+        @callbacks = nil
+      end
+
+      # Returns the non-namespaced class name of the plugin
+      #
+      #
+      # @example Non-namespaced class name for Guard::RSpec
+      #   Guard::RSpec.non_namespaced_classname
+      #   #=> "RSpec"
+      #
+      # @return [String]
+      #
+      def non_namespaced_classname
+        to_s.sub("Guard::", "")
+      end
+
+      # Returns the non-namespaced name of the plugin
+      #
+      #
+      # @example Non-namespaced name for Guard::RSpec
+      #   Guard::RSpec.non_namespaced_name
+      #   #=> "rspec"
+      #
+      # @return [String]
+      #
+      def non_namespaced_name
+        non_namespaced_classname.downcase
+      end
+
+      # Specify the source for the Guardfile template.
+      # Each Guard plugin can redefine this method to add its own logic.
+      #
+      # @param [String] plugin_location the plugin location
+      #
+      def template(plugin_location)
+        File.read(format(TEMPLATE_FORMAT, plugin_location, non_namespaced_name))
+      end
+    end
+
+    # When event is a Symbol, {#hook} will generate a hook name
+    # by concatenating the method name from where {#hook} is called
+    # with the given Symbol.
+    #
+    # @example Add a hook with a Symbol
+    #
+    #   def run_all
+    #     hook :foo
+    #   end
+    #
+    # Here, when {Guard::Plugin#run_all} is called, {#hook} will notify
+    # callbacks registered for the "run_all_foo" event.
+    #
+    # When event is a String, {#hook} will directly turn the String
+    # into a Symbol.
+    #
+    # @example Add a hook with a String
+    #
+    #   def run_all
+    #     hook "foo_bar"
+    #   end
+    #
+    # When {Guard::Plugin::run_all} is called, {#hook} will notify
+    # callbacks registered for the "foo_bar" event.
+    #
+    # @param [Symbol, String] event the name of the Guard event
+    # @param [Array] args the parameters are passed as is to the callbacks
+    #   registered for the given event.
+    #
+    def hook(event, *args)
+      hook_name = if event.is_a? Symbol
+                    calling_method = caller[0][/`([^']*)'/, 1]
+                    "#{ calling_method }_#{ event }"
+                  else
+                    event
+                  end
+
+      UI.debug "Hook :#{ hook_name } executed for #{ self.class }"
+
+      self.class.notify(self, hook_name.to_sym, *args)
+    end
+
+    # Called once when Guard starts. Please override initialize method to
+    # init stuff.
+    #
+    # @raise [:task_has_failed] when start has failed
+    # @return [Object] the task result
+    #
+    def start
+    end
+
+    # Called when `stop|quit|exit|s|q|e + enter` is pressed (when Guard
+    # quits).
+    #
+    # @raise [:task_has_failed] when stop has failed
+    # @return [Object] the task result
+    #
+    def stop
+    end
+
+    # Called when `reload|r|z + enter` is pressed.
+    # This method should be mainly used for "reload" (really!) actions like
+    # reloading passenger/spork/bundler/...
+    #
+    # @raise [:task_has_failed] when reload has failed
+    # @return [Object] the task result
+    #
+    def reload
+    end
+
+    # Called when just `enter` is pressed
+    # This method should be principally used for long action like running all
+    # specs/tests/...
+    #
+    # @raise [:task_has_failed] when run_all has failed
+    # @return [Object] the task result
+    #
+    def run_all
+    end
+
+    # Default behaviour on file(s) changes that the Guard plugin watches.
+    #
+    # @param [Array<String>] paths the changes files or paths
+    # @raise [:task_has_failed] when run_on_changes has failed
+    # @return [Object] the task result
+    #
+    def run_on_changes(paths)
+    end
+
+    # Called on file(s) additions that the Guard plugin watches.
+    #
+    # @param [Array<String>] paths the changes files or paths
+    # @raise [:task_has_failed] when run_on_additions has failed
+    # @return [Object] the task result
+    #
+    def run_on_additions(paths)
+    end
+
+    # Called on file(s) modifications that the Guard plugin watches.
+    #
+    # @param [Array<String>] paths the changes files or paths
+    # @raise [:task_has_failed] when run_on_modifications has failed
+    # @return [Object] the task result
+    #
+    def run_on_modifications(paths)
+    end
+
+    # Called on file(s) removals that the Guard plugin watches.
+    #
+    # @param [Array<String>] paths the changes files or paths
+    # @raise [:task_has_failed] when run_on_removals has failed
+    # @return [Object] the task result
+    #
+    def run_on_removals(paths)
+    end
+
+    # Returns the plugin's name (without "guard-").
+    #
+    # @example Name for Guard::RSpec
+    #   Guard::RSpec.new.name
+    #   #=> "rspec"
+    #
+    # @return [String]
+    #
+    def name
+      @name ||= self.class.non_namespaced_name
+    end
+
+    # Returns the plugin's class name without the Guard:: namespace.
+    #
+    # @example Title for Guard::RSpec
+    #   Guard::RSpec.new.title
+    #   #=> "RSpec"
+    #
+    # @return [String]
+    #
+    def title
+      @title ||= self.class.non_namespaced_classname
+    end
+
+    # String representation of the plugin.
+    #
+    # @example String representation of an instance of the Guard::RSpec plugin
+    #
+    #   Guard::RSpec.new.title
+    #   #=> "#<Guard::RSpec @name=rspec @group=#<Guard::Group @name=default
+    #   @options={}> @watchers=[] @callbacks=[] @options={all_after_pass:
+    #   true}>"
+    #
+    # @return [String] the string representation
+    #
+    def to_s
+      "#<#{self.class} @name=#{name} @group=#{group} @watchers=#{watchers}"\
+        " @callbacks=#{callbacks} @options=#{options}>"
+    end
+
+    private
+
+    # Initializes a Guard plugin.
+    # Don't do any work here, especially as Guard plugins get initialized even
+    # if they are not in an active group!
+    #
+    # @param [Hash] options the Guard plugin options
+    # @option options [Array<Guard::Watcher>] watchers the Guard plugin file
+    #   watchers
+    # @option options [Symbol] group the group this Guard plugin belongs to
+    # @option options [Boolean] any_return allow any object to be returned from
+    #   a watcher
+    #
+    def initialize(opts = {})
+      group_name = opts.delete(:group) { :default }
+      @group = Guard.state.session.groups.add(group_name)
+      @watchers = opts.delete(:watchers) { [] }
+      @callbacks = opts.delete(:callbacks) { [] }
+      @options = opts
+      _register_callbacks
+    end
+
+    # Add all the Guard::Plugin's callbacks to the global @callbacks array
+    # that's used by Guard to know which callbacks to notify.
+    #
+    def _register_callbacks
+      callbacks.each do |callback|
+        self.class.add_callback(callback[:listener], self, callback[:events])
+      end
+    end
+  end
+end

lib/guard/internals/plugins.rb

@@ -1,5 +1,6 @@
 require "guard/plugin_util"
 require "guard/group"
+require "guard/api"
 require "guard/plugin"
 
 module Guard