Remove internal-only methods from Command::Base

Command#ruby_args and Command#unwrap_string_literal are used for default command's argument backward compatibility.
Moved these methods to another module to avoid being used from custom commands.

lib/irb/command/base.rb

@@ -50,25 +50,6 @@ def initialize(irb_context)
 
       attr_reader :irb_context
 
-      def unwrap_string_literal(str)
-        return if str.empty?
-
-        sexp = Ripper.sexp(str)
-        if sexp && sexp.size == 2 && sexp.last&.first&.first == :string_literal
-          @irb_context.workspace.binding.eval(str).to_s
-        else
-          str
-        end
-      end
-
-      def ruby_args(arg)
-        # Use throw and catch to handle arg that includes `;`
-        # For example: "1, kw: (2; 3); 4" will be parsed to [[1], { kw: 3 }]
-        catch(:EXTRACT_RUBY_ARGS) do
-          @irb_context.workspace.binding.eval "IRB::Command.extract_ruby_args #{arg}"
-        end || [[], {}]
-      end
-
       def execute(arg)
         #nop
       end

lib/irb/command/edit.rb

@@ -8,6 +8,8 @@ module IRB
 
   module Command
     class Edit < Base
+      include IRB::Command::RubyArgsExtractor
+
       category "Misc"
       description 'Open a file or source location.'
       help_message <<~HELP_MESSAGE

lib/irb/command/internal_helpers.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+module IRB
+  module Command
+    # Internal use only, for default command's backward compatibility.
+    module RubyArgsExtractor # :nodoc:
+      def unwrap_string_literal(str)
+        return if str.empty?
+
+        sexp = Ripper.sexp(str)
+        if sexp && sexp.size == 2 && sexp.last&.first&.first == :string_literal
+          @irb_context.workspace.binding.eval(str).to_s
+        else
+          str
+        end
+      end
+
+      def ruby_args(arg)
+        # Use throw and catch to handle arg that includes `;`
+        # For example: "1, kw: (2; 3); 4" will be parsed to [[1], { kw: 3 }]
+        catch(:EXTRACT_RUBY_ARGS) do
+          @irb_context.workspace.binding.eval "IRB::Command.extract_ruby_args #{arg}"
+        end || [[], {}]
+      end
+    end
+  end
+end

lib/irb/command/load.rb

@@ -10,6 +10,7 @@ module IRB
 
   module Command
     class LoaderCommand < Base
+      include RubyArgsExtractor
       include IrbLoader
 
       def raise_cmd_argument_error

lib/irb/command/ls.rb

@@ -11,6 +11,8 @@ module IRB
 
   module Command
     class Ls < Base
+      include RubyArgsExtractor
+
       category "Context"
       description "Show methods, constants, and variables."
 

lib/irb/command/measure.rb

@@ -3,6 +3,8 @@ module IRB
 
   module Command
     class Measure < Base
+      include RubyArgsExtractor
+
       category "Misc"
       description "`measure` enables the mode to measure processing time. `measure :off` disables it."
 

lib/irb/command/show_doc.rb

@@ -3,6 +3,8 @@
 module IRB
   module Command
     class ShowDoc < Base
+      include RubyArgsExtractor
+
       category "Context"
       description "Look up documentation with RI."
 

lib/irb/command/show_source.rb

@@ -7,6 +7,8 @@
 module IRB
   module Command
     class ShowSource < Base
+      include RubyArgsExtractor
+
       category "Context"
       description "Show the source code of a given method, class/module, or constant."
 

lib/irb/command/subirb.rb

@@ -9,6 +9,8 @@ module IRB
 
   module Command
     class MultiIRBCommand < Base
+      include RubyArgsExtractor
+
       private
 
       def print_deprecated_warning

lib/irb/default_commands.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative "command"
+require_relative "command/internal_helpers"
 require_relative "command/context"
 require_relative "command/exit"
 require_relative "command/force_exit"