[ruby/irb] Add "show_cmds" command to list all commands'

descriptions
(https://github.com/ruby/irb/pull/463)

https://github.com/ruby/irb/commit/7e857655ac

lib/irb/cmd/backtrace.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Backtrace < Debug
+    class Backtrace < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/break.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Break < Debug
+    class Break < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/catch.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Catch < Debug
+    class Catch < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/chws.rb

@@ -19,12 +19,18 @@ module IRB
   module ExtendCommand
 
     class CurrentWorkingWorkspace < Nop
+      category "IRB"
+      description "Show the current workspace."
+
       def execute(*obj)
         irb_context.main
       end
     end
 
     class ChangeWorkspace < Nop
+      category "IRB"
+      description "Change the current workspace to an object."
+
       def execute(*obj)
         irb_context.change_workspace(*obj)
         irb_context.main

lib/irb/cmd/continue.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Continue < Debug
+    class Continue < DebugCommand
       def execute(*args)
         super(do_cmds: ["continue", *args].join(" "))
       end

lib/irb/cmd/debug.rb

@@ -5,6 +5,9 @@ module IRB
 
   module ExtendCommand
     class Debug < Nop
+      category "Debugging"
+      description "Start the debugger of debug.gem."
+
       BINDING_IRB_FRAME_REGEXPS = [
         '<internal:prelude>',
         binding.method(:irb).source_location.first,
@@ -108,5 +111,16 @@ module IRB
         end
       end
     end
+
+    class DebugCommand < Debug
+      def self.category
+        "Debugging"
+      end
+
+      def self.description
+        command_name = self.name.split("::").last.downcase
+        "Start the debugger of debug.gem and run its `#{command_name}` command."
+      end
+    end
   end
 end

lib/irb/cmd/delete.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Delete < Debug
+    class Delete < DebugCommand
       def execute(*args)
         super(pre_cmds: ["delete", *args].join(" "))
       end

lib/irb/cmd/edit.rb

@@ -6,6 +6,9 @@ module IRB
 
   module ExtendCommand
     class Edit < Nop
+      category "Misc"
+      description 'Open a file with the editor command defined with `ENV["EDITOR"]`.'
+
       class << self
         def transform_args(args)
           # Return a string literal as is for backward compatibility

lib/irb/cmd/finish.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Finish < Debug
+    class Finish < DebugCommand
       def execute(*args)
         super(do_cmds: ["finish", *args].join(" "))
       end

lib/irb/cmd/help.rb

@@ -16,6 +16,9 @@ module IRB
 
   module ExtendCommand
     class Help < Nop
+      category "Context"
+      description "Enter the mode to look up RI documents."
+
       def execute(*names)
         require 'rdoc/ri/driver'
         opts = RDoc::RI::Driver.process_args([])

lib/irb/cmd/info.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Info < Debug
+    class Info < DebugCommand
       def self.transform_args(args)
         args&.dump
       end

lib/irb/cmd/irb_info.rb

@@ -7,6 +7,9 @@ module IRB
 
   module ExtendCommand
     class IrbInfo < Nop
+      category "IRB"
+      description "Show information about IRB."
+
       def execute
         Class.new {
           def inspect

lib/irb/cmd/load.rb

@@ -20,6 +20,9 @@ module IRB
     class Load < Nop
       include IrbLoader
 
+      category "IRB"
+      description "Load a Ruby file."
+
       def execute(file_name, priv = nil)
         return irb_load(file_name, priv)
       end
@@ -28,6 +31,9 @@ module IRB
     class Require < Nop
       include IrbLoader
 
+      category "IRB"
+      description "Require a Ruby file."
+
       def execute(file_name)
 
         rex = Regexp.new("#{Regexp.quote(file_name)}(\.o|\.rb)?")
@@ -58,6 +64,10 @@ module IRB
 
     class Source < Nop
       include IrbLoader
+
+      category "IRB"
+      description "Loads a given file in the current session."
+
       def execute(file_name)
         source_file(file_name)
       end

lib/irb/cmd/ls.rb

@@ -9,6 +9,9 @@ module IRB
 
   module ExtendCommand
     class Ls < Nop
+      category "Context"
+      description "Show methods, constants, and variables. `-g [query]` or `-G [query]` allows you to filter out the output."
+
       def self.transform_args(args)
         if match = args&.match(/\A(?<args>.+\s|)(-g|-G)\s+(?<grep>[^\s]+)\s*\n\z/)
           args = match[:args]

lib/irb/cmd/measure.rb

@@ -5,6 +5,9 @@ module IRB
 
   module ExtendCommand
     class Measure < Nop
+      category "Misc"
+      description "`measure` enables the mode to measure processing time. `measure :off` disables it."
+
       def initialize(*args)
         super(*args)
       end

lib/irb/cmd/next.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Next < Debug
+    class Next < DebugCommand
       def execute(*args)
         super(do_cmds: ["next", *args].join(" "))
       end

lib/irb/cmd/nop.rb

@@ -14,6 +14,17 @@ module IRB
 
   module ExtendCommand
     class Nop
+      class << self
+        def category(category = nil)
+          @category = category if category
+          @category
+        end
+
+        def description(description = nil)
+          @description = description if description
+          @description
+        end
+      end
 
       if RUBY_ENGINE == "ruby" && RUBY_VERSION >= "2.7.0"
         def self.execute(conf, *opts, **kwargs, &block)

lib/irb/cmd/pushws.rb

@@ -18,12 +18,18 @@ module IRB
 
   module ExtendCommand
     class Workspaces < Nop
+      category "IRB"
+      description "Show workspaces."
+
       def execute(*obj)
         irb_context.workspaces.collect{|ws| ws.main}
       end
     end
 
     class PushWorkspace < Workspaces
+      category "IRB"
+      description "Push an object to the workspace stack."
+
       def execute(*obj)
         irb_context.push_workspace(*obj)
         super
@@ -31,6 +37,9 @@ module IRB
     end
 
     class PopWorkspace < Workspaces
+      category "IRB"
+      description "Pop a workspace from the workspace stack."
+
       def execute(*obj)
         irb_context.pop_workspace(*obj)
         super

lib/irb/cmd/show_cmds.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require "stringio"
+require_relative "nop"
+
+module IRB
+  # :stopdoc:
+
+  module ExtendCommand
+    class ShowCmds < Nop
+      category "IRB"
+      description "List all available commands and their description."
+
+      def execute(*args)
+        commands_info = IRB::ExtendCommandBundle.all_commands_info
+        commands_grouped_by_categories = commands_info.group_by { |cmd| cmd[:category] }
+        longest_cmd_name_length = commands_info.map { |c| c[:display_name] }.max { |a, b| a.length <=> b.length }.length
+
+        output = StringIO.new
+
+        commands_grouped_by_categories.each do |category, cmds|
+          output.puts Color.colorize(category, [:BOLD])
+
+          cmds.each do |cmd|
+            output.puts "  #{cmd[:display_name].to_s.ljust(longest_cmd_name_length)}    #{cmd[:description]}"
+          end
+
+          output.puts
+        end
+
+        puts output.string
+
+        nil
+      end
+    end
+  end
+
+  # :startdoc:
+end

lib/irb/cmd/show_source.rb

@@ -9,6 +9,9 @@ module IRB
 
   module ExtendCommand
     class ShowSource < Nop
+      category "Context"
+      description "Show the source code of a given method or constant."
+
       class << self
         def transform_args(args)
           # Return a string literal as is for backward compatibility

lib/irb/cmd/step.rb

@@ -6,7 +6,7 @@ module IRB
   # :stopdoc:
 
   module ExtendCommand
-    class Step < Debug
+    class Step < DebugCommand
       def execute(*args)
         # Run `next` first to move out of binding.irb
         super(pre_cmds: "next", do_cmds: ["step", *args].join(" "))

lib/irb/cmd/subirb.rb

@@ -30,24 +30,36 @@ module IRB
     end
 
     class IrbCommand < MultiIRBCommand
+      category "IRB"
+      description "Start a child IRB."
+
       def execute(*obj)
         IRB.irb(nil, *obj)
       end
     end
 
     class Jobs < MultiIRBCommand
+      category "IRB"
+      description "List of current sessions."
+
       def execute
         IRB.JobManager
       end
     end
 
     class Foreground < MultiIRBCommand
+      category "IRB"
+      description "Switches to the session of the given number."
+
       def execute(key)
         IRB.JobManager.switch(key)
       end
     end
 
     class Kill < MultiIRBCommand
+      category "IRB"
+      description "Kills the session with the given number."
+
       def execute(*keys)
         IRB.JobManager.kill(*keys)
       end

lib/irb/cmd/whereami.rb

@@ -7,6 +7,9 @@ module IRB
 
   module ExtendCommand
     class Whereami < Nop
+      category "Context"
+      description "Show the source code around binding.irb again."
+
       def execute(*)
         code = irb_context.workspace.code_around_binding
         if code

lib/irb/extend-command.rb

@@ -45,14 +45,15 @@ module IRB # :nodoc:
       [:quit, :irb_exit, OVERRIDE_PRIVATE_ONLY],
     ]
 
+
     @EXTEND_COMMANDS = [
       [
         :irb_current_working_workspace, :CurrentWorkingWorkspace, "cmd/chws",
+        [:cwws, NO_OVERRIDE],
+        [:pwws, NO_OVERRIDE],
         [:irb_print_working_workspace, OVERRIDE_ALL],
         [:irb_cwws, OVERRIDE_ALL],
         [:irb_pwws, OVERRIDE_ALL],
-        [:cwws, NO_OVERRIDE],
-        [:pwws, NO_OVERRIDE],
         [:irb_current_working_binding, OVERRIDE_ALL],
         [:irb_print_working_binding, OVERRIDE_ALL],
         [:irb_cwb, OVERRIDE_ALL],
@@ -60,10 +61,10 @@ module IRB # :nodoc:
       ],
       [
         :irb_change_workspace, :ChangeWorkspace, "cmd/chws",
-        [:irb_chws, OVERRIDE_ALL],
-        [:irb_cws, OVERRIDE_ALL],
         [:chws, NO_OVERRIDE],
         [:cws, NO_OVERRIDE],
+        [:irb_chws, OVERRIDE_ALL],
+        [:irb_cws, OVERRIDE_ALL],
         [:irb_change_binding, OVERRIDE_ALL],
         [:irb_cb, OVERRIDE_ALL],
         [:cb, NO_OVERRIDE],
@@ -77,16 +78,16 @@ module IRB # :nodoc:
       ],
       [
         :irb_push_workspace, :PushWorkspace, "cmd/pushws",
-        [:irb_pushws, OVERRIDE_ALL],
         [:pushws, NO_OVERRIDE],
+        [:irb_pushws, OVERRIDE_ALL],
         [:irb_push_binding, OVERRIDE_ALL],
         [:irb_pushb, OVERRIDE_ALL],
         [:pushb, NO_OVERRIDE],
       ],
       [
         :irb_pop_workspace, :PopWorkspace, "cmd/pushws",
-        [:irb_popws, OVERRIDE_ALL],
         [:popws, NO_OVERRIDE],
+        [:irb_popws, OVERRIDE_ALL],
         [:irb_pop_binding, OVERRIDE_ALL],
         [:irb_popb, OVERRIDE_ALL],
         [:popb, NO_OVERRIDE],
@@ -131,7 +132,7 @@ module IRB # :nodoc:
         :irb_catch, :Catch, "cmd/catch",
       ],
       [
-        :irb_next, :Next, "cmd/next",
+        :irb_next, :Next, "cmd/next"
       ],
       [
         :irb_delete, :Delete, "cmd/delete",
@@ -187,9 +188,41 @@ module IRB # :nodoc:
         :irb_whereami, :Whereami, "cmd/whereami",
         [:whereami, NO_OVERRIDE],
       ],
-
+      [
+        :irb_show_cmds, :ShowCmds, "cmd/show_cmds",
+        [:show_cmds, NO_OVERRIDE],
+      ]
     ]
 
+
+    @@commands = []
+
+    def self.all_commands_info
+      return @@commands unless @@commands.empty?
+      user_aliases = IRB.CurrentContext.command_aliases.each_with_object({}) do |(alias_name, target), result|
+        result[target] ||= []
+        result[target] << alias_name
+      end
+
+      @EXTEND_COMMANDS.each do |cmd_name, cmd_class, load_file, *aliases|
+        if !defined?(ExtendCommand) || !ExtendCommand.const_defined?(cmd_class, false)
+          require_relative load_file
+        end
+
+        klass = ExtendCommand.const_get(cmd_class, false)
+        aliases = aliases.map { |a| a.first }
+
+        if additional_aliases = user_aliases[cmd_name]
+          aliases += additional_aliases
+        end
+
+        display_name = aliases.shift || cmd_name
+        @@commands << { display_name: display_name, description: klass.description, category: klass.category }
+      end
+
+      @@commands
+    end
+
     # Convert a command name to its implementation class if such command exists
     def self.load_command(command)
       command = command.to_sym

test/irb/test_cmd.rb

@@ -583,6 +583,16 @@ module TestIRB
       $bar = nil
     end
 
+    def test_show_cmds
+      out, err = execute_lines(
+        "show_cmds\n"
+      )
+
+      assert_empty err
+      assert_match(/List all available commands and their description/, out)
+      assert_match(/Start the debugger of debug\.gem/, out)
+    end
+
     class EditTest < CommandTestCase
       def setup
         @original_editor = ENV["EDITOR"]