undo: move another piece of checking to the two places that need it

And in the bargain get rid of a function that is used just once.

src/cut.c

@@ -33,12 +33,6 @@ void cutbuffer_reset(void)
 	keep_cutbuffer = FALSE;
 }
 
-/* Return the status of cutbuffer preservation. */
-inline bool keeping_cutbuffer(void)
-{
-	return keep_cutbuffer;
-}
-
 /* If we aren't on the last line of the file, move all the text of the
  * current line, plus the newline at the end, into the cutbuffer.  If we
  * are, move all of the text of the current line into the cutbuffer.  In
@@ -193,7 +187,12 @@ void do_cut_text(bool copy_text, bool marked, bool cut_till_eof)
 void do_cut_text_void(void)
 {
 #ifndef NANO_TINY
-	add_undo(CUT);
+	/* Only add a new undo item when the current item is not a CUT or when
+	 * the current cut is not contiguous with the previous cutting. */
+	if (openfile->last_action != CUT || openfile->current_undo == NULL ||
+			openfile->current_undo->mark_begin_lineno != openfile->current->lineno ||
+			!keep_cutbuffer)
+		add_undo(CUT);
 	do_cut_text(FALSE, openfile->mark, FALSE);
 	update_undo(CUT);
 #else

src/nano.c

@@ -1885,7 +1885,12 @@ void do_output(char *output, size_t output_len, bool allow_cntrls)
 		set_modified();
 
 #ifndef NANO_TINY
-		add_undo(ADD);
+		/* Only add a new undo item when the current item is not an ADD or when
+		 * the current typing is not contiguous with the previous typing. */
+		if (openfile->last_action != ADD || openfile->current_undo == NULL ||
+				openfile->current_undo->mark_begin_lineno != openfile->current->lineno ||
+				openfile->current_undo->mark_begin_x != openfile->current_x)
+			add_undo(ADD);
 
 		/* Note that current_x has not yet been incremented. */
 		if (openfile->current == openfile->mark &&

src/proto.h

@@ -251,7 +251,6 @@ void precalc_multicolorinfo(void);
 
 /* Most functions in cut.c. */
 void cutbuffer_reset(void);
-bool keeping_cutbuffer(void);
 #ifndef NANO_TINY
 void cut_marked(bool *right_side_up);
 #endif

src/text.c

@@ -1319,14 +1319,6 @@ void add_undo(undo_type action)
 	undo *u = openfile->current_undo;
 		/* The thing we did previously. */
 
-	/* When doing contiguous adds or cuts, don't add a new undo item, but
-	 * let a later update call update the existing item. */
-	if (u != NULL && action == openfile->last_action && action == u->type &&
-					openfile->current->lineno == u->mark_begin_lineno &&
-					((action == ADD && u->mark_begin_x == openfile->current_x) ||
-					(action == CUT && keeping_cutbuffer())))
-		return;
-
 	/* Blow away newer undo items if we add somewhere in the middle. */
 	discard_until(u, openfile, TRUE);