Type based completion using Prism and RBS

Gemfile

@@ -17,3 +17,7 @@ gem "rake"
 gem "test-unit"
 gem "test-unit-ruby-core"
 gem "debug", github: "ruby/debug"
+if RUBY_VERSION >= "3.0.0"
+  gem "rbs"
+  gem "prism"
+end

Rakefile

@@ -5,15 +5,15 @@ Rake::TestTask.new(:test) do |t|
   t.libs << "test" << "test/lib"
   t.libs << "lib"
   t.ruby_opts << "-rhelper"
-  t.test_files = FileList["test/irb/test_*.rb"]
+  t.test_files = FileList["test/irb/test_*.rb", "test/irb/type_completion/test_*.rb"]
 end
 
 # To make sure they have been correctly setup for Ruby CI.
 desc "Run each irb test file in isolation."
 task :test_in_isolation do
   failed = false
 
-  FileList["test/irb/test_*.rb"].each do |test_file|
+  FileList["test/irb/test_*.rb", "test/irb/type_completion/test_*.rb"].each do |test_file|
     ENV["TEST"] = test_file
     begin
       Rake::Task["test"].execute

lib/irb.rb

@@ -140,6 +140,10 @@
 #
 #     IRB.conf[:USE_AUTOCOMPLETE] = false
 #
+# To enable enhanced completion using type information, add the following to your +.irbrc+:
+#
+#     IRB.conf[:COMPLETOR] = :type
+#
 # === History
 #
 # By default, irb will store the last 1000 commands you used in

lib/irb/cmd/irb_info.rb

@@ -14,6 +14,7 @@ def execute
         str  = "Ruby version: #{RUBY_VERSION}\n"
         str += "IRB version: #{IRB.version}\n"
         str += "InputMethod: #{IRB.CurrentContext.io.inspect}\n"
+        str += "Completion: #{IRB.CurrentContext.io.respond_to?(:completion_info) ? IRB.CurrentContext.io.completion_info : 'off'}\n"
         str += ".irbrc path: #{IRB.rc_file}\n" if File.exist?(IRB.rc_file)
         str += "RUBY_PLATFORM: #{RUBY_PLATFORM}\n"
         str += "LANG env: #{ENV["LANG"]}\n" if ENV["LANG"] && !ENV["LANG"].empty?

lib/irb/completion.rb

@@ -9,6 +9,30 @@
 
 module IRB
   class BaseCompletor # :nodoc:
+
+    # Set of reserved words used by Ruby, you should not use these for
+    # constants or variables
+    ReservedWords = %w[
+      __ENCODING__ __LINE__ __FILE__
+      BEGIN END
+      alias and
+      begin break
+      case class
+      def defined? do
+      else elsif end ensure
+      false for
+      if in
+      module
+      next nil not
+      or
+      redo rescue retry return
+      self super
+      then true
+      undef unless until
+      when while
+      yield
+    ]
+
     def completion_candidates(preposing, target, postposing, bind:)
       raise NotImplementedError
     end
@@ -94,28 +118,9 @@ def eval_class_constants
       end
     }
 
-    # Set of reserved words used by Ruby, you should not use these for
-    # constants or variables
-    ReservedWords = %w[
-      __ENCODING__ __LINE__ __FILE__
-      BEGIN END
-      alias and
-      begin break
-      case class
-      def defined? do
-      else elsif end ensure
-      false for
-      if in
-      module
-      next nil not
-      or
-      redo rescue retry return
-      self super
-      then true
-      undef unless until
-      when while
-      yield
-    ]
+    def inspect
+      'RegexpCompletor'
+    end
 
     def complete_require_path(target, preposing, postposing)
       if target =~ /\A(['"])([^'"]+)\Z/

lib/irb/context.rb

@@ -86,14 +86,14 @@ def initialize(irb, workspace = nil, input_method = nil)
         when nil
           if STDIN.tty? && IRB.conf[:PROMPT_MODE] != :INF_RUBY && !use_singleline?
             # Both of multiline mode and singleline mode aren't specified.
-            @io = RelineInputMethod.new
+            @io = RelineInputMethod.new(build_completor)
           else
             @io = nil
           end
         when false
           @io = nil
         when true
-          @io = RelineInputMethod.new
+          @io = RelineInputMethod.new(build_completor)
         end
         unless @io
           case use_singleline?
@@ -149,6 +149,21 @@ def initialize(irb, workspace = nil, input_method = nil)
       @command_aliases = IRB.conf[:COMMAND_ALIASES]
     end
 
+    private def build_completor
+      # Valid values are :regexp and :type
+      if IRB.conf[:COMPLETOR] == :type && RUBY_VERSION >= '3.0.0'
+        begin
+          require 'prism'
+          require 'irb/type_completion/completor'
+          TypeCompletion::Types.preload_in_thread
+          return TypeCompletion::Completor.new
+        rescue LoadError
+        end
+      end
+      # Fallback to RegexpCompletor
+      RegexpCompletor.new
+    end
+
     def save_history=(val)
       IRB.conf[:SAVE_HISTORY] = val
     end

lib/irb/init.rb

@@ -76,6 +76,7 @@ def IRB.init_config(ap_path)
     @CONF[:USE_SINGLELINE] = false unless defined?(ReadlineInputMethod)
     @CONF[:USE_COLORIZE] = (nc = ENV['NO_COLOR']).nil? || nc.empty?
     @CONF[:USE_AUTOCOMPLETE] = ENV.fetch("IRB_USE_AUTOCOMPLETE", "true") != "false"
+    @CONF[:COMPLETOR] = :regexp
     @CONF[:INSPECT_MODE] = true
     @CONF[:USE_TRACER] = false
     @CONF[:USE_LOADER] = false

lib/irb/input-method.rb

@@ -193,6 +193,10 @@ def initialize
       }
     end
 
+    def completion_info
+      'RegexpCompletor'
+    end
+
     # Reads the next line from this input method.
     #
     # See IO#gets for more information.
@@ -230,13 +234,13 @@ class RelineInputMethod < StdioInputMethod
     HISTORY = Reline::HISTORY
     include HistorySavingAbility
     # Creates a new input method object using Reline
-    def initialize
+    def initialize(completor)
       IRB.__send__(:set_encoding, Reline.encoding_system_needs.name, override: false)
 
-      super
+      super()
 
       @eof = false
-      @completor = RegexpCompletor.new
+      @completor = completor
 
       Reline.basic_word_break_characters = BASIC_WORD_BREAK_CHARACTERS
       Reline.completion_append_character = nil
@@ -270,6 +274,11 @@ def initialize
       end
     end
 
+    def completion_info
+      autocomplete_message = IRB.conf[:USE_AUTOCOMPLETE] ? 'Autocomplete' : 'Tab Complete'
+      "#{autocomplete_message}, #{@completor.inspect}"
+    end
+
     def check_termination(&block)
       @check_termination_proc = block
     end