Rename current completor to RegexpCompletor and refactored for future…

… extension (#707)

* Move completion implementation to completion/regexp_completor for future extension

* Remove constant CompletionProc and PerfectMatchedProc and add a class method

* Move document display logic to InputCompletor. Each completor only need to implement `completion_caididates` and `doc_namespace`

* Move display_document logic to RelineInputMethod

* Use RegexpCompletor directly. Not through class method of InputCompletor.

* RegexpCompletor extends BaseCompletor, move back definition to completion.rb

* Move display_document test to input_method test

* Stop re-initialize completor on each completion phase

* Store completor to ReadlineInputMethod's iver

lib/irb/completion.rb

@@ -8,55 +8,14 @@
 require_relative 'ruby-lex'
 
 module IRB
-  module InputCompletor # :nodoc:
-    using Module.new {
-      refine ::Binding do
-        def eval_methods
-          ::Kernel.instance_method(:methods).bind(eval("self")).call
-        end
-
-        def eval_private_methods
-          ::Kernel.instance_method(:private_methods).bind(eval("self")).call
-        end
-
-        def eval_instance_variables
-          ::Kernel.instance_method(:instance_variables).bind(eval("self")).call
-        end
-
-        def eval_global_variables
-          ::Kernel.instance_method(:global_variables).bind(eval("self")).call
-        end
-
-        def eval_class_constants
-          ::Module.instance_method(:constants).bind(eval("self.class")).call
-        end
-      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
-    ]
+  class BaseCompletor # :nodoc:
+    def completion_candidates(preposing, target, postposing, bind:)
+      raise NotImplementedError
+    end
 
-    BASIC_WORD_BREAK_CHARACTERS = " \t\n`><=;|&{("
+    def doc_namespace(preposing, matched, postposing, bind:)
+      raise NotImplementedError
+    end
 
     GEM_PATHS =
       if defined?(Gem::Specification)
@@ -73,7 +32,7 @@ def defined? do
         []
       end.freeze
 
-    def self.retrieve_gem_and_system_load_path
+    def retrieve_gem_and_system_load_path
       candidates = (GEM_PATHS | $LOAD_PATH)
       candidates.map do |p|
         if p.respond_to?(:to_path)
@@ -84,8 +43,8 @@ def self.retrieve_gem_and_system_load_path
       end.compact.sort
     end
 
-    def self.retrieve_files_to_require_from_load_path
-      @@files_from_load_path ||=
+    def retrieve_files_to_require_from_load_path
+      @files_from_load_path ||=
         (
           shortest = []
           rest = retrieve_gem_and_system_load_path.each_with_object([]) { |path, result|
@@ -103,13 +62,62 @@ def self.retrieve_files_to_require_from_load_path
         )
     end
 
-    def self.retrieve_files_to_require_relative_from_current_dir
-      @@files_from_current_dir ||= Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: '.').map { |path|
+    def retrieve_files_to_require_relative_from_current_dir
+      @files_from_current_dir ||= Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: '.').map { |path|
         path.sub(/\.(rb|#{RbConfig::CONFIG['DLEXT']})\z/, '')
       }
     end
+  end
 
-    CompletionRequireProc = lambda { |target, preposing = nil, postposing = nil|
+  class RegexpCompletor < BaseCompletor # :nodoc:
+    using Module.new {
+      refine ::Binding do
+        def eval_methods
+          ::Kernel.instance_method(:methods).bind(eval("self")).call
+        end
+
+        def eval_private_methods
+          ::Kernel.instance_method(:private_methods).bind(eval("self")).call
+        end
+
+        def eval_instance_variables
+          ::Kernel.instance_method(:instance_variables).bind(eval("self")).call
+        end
+
+        def eval_global_variables
+          ::Kernel.instance_method(:global_variables).bind(eval("self")).call
+        end
+
+        def eval_class_constants
+          ::Module.instance_method(:constants).bind(eval("self.class")).call
+        end
+      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 complete_require_path(target, preposing, postposing)
       if target =~ /\A(['"])([^'"]+)\Z/
         quote = $1
         actual_target = $2
@@ -142,21 +150,21 @@ def self.retrieve_files_to_require_relative_from_current_dir
         end
       end
       result
-    }
+    end
 
-    CompletionProc = lambda { |target, preposing = nil, postposing = nil|
+    def completion_candidates(preposing, target, postposing, bind:)
       if preposing && postposing
-        result = CompletionRequireProc.(target, preposing, postposing)
-        unless result
-          result = retrieve_completion_data(target).compact.map{ |i| i.encode(Encoding.default_external) }
-        end
-        result
-      else
-        retrieve_completion_data(target).compact.map{ |i| i.encode(Encoding.default_external) }
+        result = complete_require_path(target, preposing, postposing)
+        return result if result
       end
-    }
+      retrieve_completion_data(target, bind: bind, doc_namespace: false).compact.map{ |i| i.encode(Encoding.default_external) }
+    end
 
-    def self.retrieve_completion_data(input, bind: IRB.conf[:MAIN_CONTEXT].workspace.binding, doc_namespace: false)
+    def doc_namespace(_preposing, matched, _postposing, bind:)
+      retrieve_completion_data(matched, bind: bind, doc_namespace: true)
+    end
+
+    def retrieve_completion_data(input, bind:, doc_namespace:)
       case input
       # this regexp only matches the closing character because of irb's Reline.completer_quote_characters setting
       # details are described in: https://github.com/ruby/irb/pull/523
@@ -394,44 +402,10 @@ def self.retrieve_completion_data(input, bind: IRB.conf[:MAIN_CONTEXT].workspace
       end
     end
 
-    PerfectMatchedProc = ->(matched, bind: IRB.conf[:MAIN_CONTEXT].workspace.binding) {
-      begin
-        require 'rdoc'
-      rescue LoadError
-        return
-      end
-
-      RDocRIDriver ||= RDoc::RI::Driver.new
-
-      if matched =~ /\A(?:::)?RubyVM/ and not ENV['RUBY_YES_I_AM_NOT_A_NORMAL_USER']
-        IRB.__send__(:easter_egg)
-        return
-      end
-
-      namespace = retrieve_completion_data(matched, bind: bind, doc_namespace: true)
-      return unless namespace
-
-      if namespace.is_a?(Array)
-        out = RDoc::Markup::Document.new
-        namespace.each do |m|
-          begin
-            RDocRIDriver.add_method(out, m)
-          rescue RDoc::RI::Driver::NotFoundError
-          end
-        end
-        RDocRIDriver.display(out)
-      else
-        begin
-          RDocRIDriver.display_names([namespace])
-        rescue RDoc::RI::Driver::NotFoundError
-        end
-      end
-    }
-
     # Set of available operators in Ruby
     Operators = %w[% & * ** + - / < << <= <=> == === =~ > >= >> [] []= ^ ! != !~]
 
-    def self.select_message(receiver, message, candidates, sep = ".")
+    def select_message(receiver, message, candidates, sep = ".")
       candidates.grep(/^#{Regexp.quote(message)}/).collect do |e|
         case e
         when /^[a-zA-Z_]/