tweaks: factor out a three-line condition into a separate function

For clarity.

src/cut.c

@@ -330,10 +330,8 @@ void ingraft_buffer(linestruct *topline)
 	bool edittop_inside = (openfile->edittop == openfile->current);
 #ifndef NANO_TINY
 	/* Remember whether mark and cursor are on the same line, and their order. */
+	bool right_side_up = (openfile->mark && mark_is_before_cursor());
 	bool same_line = (openfile->mark == openfile->current);
-	bool right_side_up = (openfile->mark &&
-						(openfile->mark->lineno < openfile->current->lineno ||
-						(same_line && openfile->mark_x <= openfile->current_x)));
 #endif
 
 	/* Partition the buffer so that it contains no text, then delete it.*/

src/proto.h

@@ -578,6 +578,7 @@ void new_magicline(void);
 void remove_magicline(void);
 #endif
 #ifndef NANO_TINY
+bool mark_is_before_cursor(void);
 void get_region(const linestruct **top, size_t *top_x,
 		const linestruct **bot, size_t *bot_x, bool *right_side_up);
 void get_range(const linestruct **top, const linestruct **bot);

src/text.c

@@ -1181,9 +1181,7 @@ void add_undo(undo_type action, const char *message)
 	case CUT:
 		if (openfile->mark) {
 			u->xflags |= MARK_WAS_SET;
-			if (openfile->mark->lineno < openfile->current->lineno ||
+			if (mark_is_before_cursor()){
-							(openfile->mark == openfile->current &&
-							openfile->mark_x < openfile->current_x)) {
 				u->head_lineno = openfile->mark->lineno;
 				u->head_x = openfile->mark_x;
 			} else {
@@ -2552,10 +2550,8 @@ const char *treat(char *tempfile_name, char *theprogram, bool spelling)
 #ifndef NANO_TINY
 	/* Replace the marked text (or entire text) with the corrected text. */
 	if (spelling && openfile->mark) {
-		bool upright = (openfile->mark->lineno < openfile->current->lineno ||
-								(openfile->mark == openfile->current &&
-								openfile->mark_x < openfile->current_x));
 		ssize_t was_mark_lineno = openfile->mark->lineno;
+		bool upright = mark_is_before_cursor();
 
 		replaced = replace_buffer(tempfile_name, CUT, TRUE, "spelling correction");
 

src/utils.c

@@ -450,15 +450,21 @@ void remove_magicline(void)
 #endif
 
 #ifndef NANO_TINY
+/* Return TRUE when the mark is before or at the cursor, and FALSE otherwise. */
+bool mark_is_before_cursor(void)
+{
+	return (openfile->mark->lineno < openfile->current->lineno ||
+						(openfile->mark == openfile->current &&
+						openfile->mark_x <= openfile->current_x));
+}
+
 /* Return in (top, top_x) and (bot, bot_x) the start and end "coordinates"
  * of the marked region.  If right_side_up isn't NULL, set it to TRUE when
  * the mark is at the top of the marked region, and to FALSE otherwise. */
 void get_region(const linestruct **top, size_t *top_x,
 				const linestruct **bot, size_t *bot_x, bool *right_side_up)
 {
-	if (openfile->mark->lineno < openfile->current->lineno ||
+	if (mark_is_before_cursor()) {
-				(openfile->mark == openfile->current &&
-				openfile->mark_x < openfile->current_x)) {
 		*top = openfile->mark;
 		*top_x = openfile->mark_x;
 		*bot = openfile->current;