Refactor IRB::Context#prompting (#889)

Author: st0012

lib/irb/context.rb

@@ -479,9 +479,7 @@ def verbose?
     # StdioInputMethod or RelineInputMethod or ReadlineInputMethod, see #io
     # for more information.
     def prompting?
-      verbose? || (STDIN.tty? && @io.kind_of?(StdioInputMethod) ||
-                   @io.kind_of?(RelineInputMethod) ||
-                   (defined?(ReadlineInputMethod) && @io.kind_of?(ReadlineInputMethod)))
+      verbose? || @io.prompting?
     end
 
     # The return value of the last statement evaluated.

lib/irb/input-method.rb

@@ -44,6 +44,10 @@ def support_history_saving?
       false
     end
 
+    def prompting?
+      false
+    end
+
     # For debug message
     def inspect
       'Abstract InputMethod'
@@ -91,6 +95,10 @@ def readable_after_eof?
       true
     end
 
+    def prompting?
+      STDIN.tty?
+    end
+
     # Returns the current line number for #io.
     #
     # #line counts the number of times #gets is called.
@@ -220,6 +228,10 @@ def eof?
       @eof
     end
 
+    def prompting?
+      true
+    end
+
     # For debug message
     def inspect
       readline_impl = (defined?(Reline) && Readline == Reline) ? 'Reline' : 'ext/readline'
@@ -467,6 +479,10 @@ def eof?
       @eof
     end
 
+    def prompting?
+      true
+    end
+
     # For debug message
     def inspect
       config = Reline::Config.new