[ruby/irb] Use gem repl_type_completor, remove type_completion

implementation
(ruby/irb#772)

ruby/irb@a4868a5373

lib/irb/completion.rb

@@ -93,6 +93,27 @@ def retrieve_files_to_require_relative_from_current_dir
     end
   end
 
+  class TypeCompletor < BaseCompletor # :nodoc:
+    def initialize(context)
+      @context = context
+    end
+
+    def inspect
+      ReplTypeCompletor.info
+    end
+
+    def completion_candidates(preposing, target, _postposing, bind:)
+      result = ReplTypeCompletor.analyze(preposing + target, binding: bind, filename: @context.irb_path)
+      return [] unless result
+      result.completion_candidates.map { target + _1 }
+    end
+
+    def doc_namespace(preposing, matched, _postposing, bind:)
+      result = ReplTypeCompletor.analyze(preposing + matched, binding: bind, filename: @context.irb_path)
+      result&.doc_namespace('')
+    end
+  end
+
   class RegexpCompletor < BaseCompletor # :nodoc:
     using Module.new {
       refine ::Binding do

lib/irb/context.rb

@@ -176,26 +176,22 @@ def initialize(irb, workspace = nil, input_method = nil)
       RegexpCompletor.new
     end
 
-    TYPE_COMPLETION_REQUIRED_PRISM_VERSION = '0.18.0'
-
     private def build_type_completor
-      unless Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0') && RUBY_ENGINE != 'truffleruby'
-        warn 'TypeCompletion requires RUBY_VERSION >= 3.0.0'
+      if RUBY_ENGINE == 'truffleruby'
+        # Avoid SynatxError. truffleruby does not support endless method definition yet.
+        warn 'TypeCompletor is not supported on TruffleRuby yet'
         return
       end
+
       begin
-        require 'prism'
+        require 'repl_type_completor'
       rescue LoadError => e
-        warn "TypeCompletion requires Prism: #{e.message}"
+        warn "TypeCompletor requires `gem repl_type_completor`: #{e.message}"
         return
       end
-      unless Gem::Version.new(Prism::VERSION) >= Gem::Version.new(TYPE_COMPLETION_REQUIRED_PRISM_VERSION)
-        warn "TypeCompletion requires Prism::VERSION >= #{TYPE_COMPLETION_REQUIRED_PRISM_VERSION}"
-        return
-      end
-      require 'irb/type_completion/completor'
-      TypeCompletion::Types.preload_in_thread
-      TypeCompletion::Completor.new
+
+      ReplTypeCompletor.preload_rbs
+      TypeCompletor.new(self)
     end
 
     def save_history=(val)