wrapping: improve the persistence of the prepending behavior

Now you can have a look elsewhere in the buffer (and even delete
or paste stuff there) and when you return to the original line
and continue typing, any spillover from automatic hard-wrapping
will spill over onto the same line it spilled over to before.

You can even switch to a different buffer and return and continue
typing, and stuff will still spill over to the same line.

In the bargain, this gets rid of a bit of flag-resetting code
that was run for many keystrokes, in most cases needlessly.

This addresses https://savannah.gnu.org/bugs/?56189.

src/files.c

@@ -94,6 +94,9 @@ void make_new_buffer(void)
 	openfile->current_y = 0;
 
 	openfile->modified = FALSE;
+#ifdef ENABLE_WRAPPING
+	openfile->spillage_line = NULL;
+#endif
 #ifndef NANO_TINY
 	openfile->mark = NULL;
 

src/nano.c

@@ -131,6 +131,11 @@ void unlink_node(linestruct *fileptr)
 /* Free the data structures in the given node. */
 void delete_node(linestruct *fileptr)
 {
+#ifdef ENABLE_WRAPPING
+	/* If the spill-over line for hard-wrapping is deleted... */
+	if (fileptr == openfile->spillage_line)
+		openfile->spillage_line = NULL;
+#endif
 	free(fileptr->data);
 #ifdef ENABLE_COLOR
 	free(fileptr->multidata);
@@ -1780,9 +1785,6 @@ void do_input(void)
 		} else
 #endif
 		{
-#ifdef ENABLE_WRAPPING
-			linestruct *was_next = openfile->current->next;
-#endif
 #ifndef NANO_TINY
 			linestruct *was_current = openfile->current;
 			size_t was_x = openfile->current_x;
@@ -1812,14 +1814,6 @@ void do_input(void)
 					also_the_last = FALSE;
 			}
 #endif
-#ifdef ENABLE_WRAPPING
-			/* If the cursor moved to another line and this was not caused
-			 * by adding characters to the buffer, clear the prepend flag. */
-			if (openfile->current->next != was_next &&
-							shortcut->func != do_tab &&
-							shortcut->func != do_verbatim_input)
-				wrap_reset();
-#endif
 #ifdef ENABLE_COLOR
 			if (!refresh_needed && !okay_for_view(shortcut))
 				check_the_multis(openfile->current);

src/nano.h

@@ -383,6 +383,10 @@ typedef struct openfilestruct {
 		/* Whether the file has been modified. */
 	struct stat *current_stat;
 		/* The file's current stat information. */
+#ifdef ENABLE_WRAPPING
+	linestruct *spillage_line;
+		/* The line for prepending stuff to during automatic hard-wrapping. */
+#endif
 #ifndef NANO_TINY
 	linestruct *mark;
 		/* The line in the file where the mark is set; NULL if not set. */

src/proto.h

@@ -525,7 +525,6 @@ void update_multiline_undo(ssize_t lineno, char *indentation);
 void update_undo(undo_type action);
 #endif /* !NANO_TINY */
 #ifdef ENABLE_WRAPPING
-void wrap_reset(void);
 bool do_wrap(void);
 #endif
 #if defined(ENABLE_HELP) || defined(ENABLED_WRAPORJUSTIFY)

src/text.c

@@ -35,11 +35,6 @@
 static pid_t pid_of_command = -1;
 		/* The PID of the forked process -- needed when wanting to abort it. */
 #endif
-#ifdef ENABLE_WRAPPING
-static bool prepend_wrap = FALSE;
-		/* Should we prepend wrapped text to the next line? */
-#endif
-
 #ifdef ENABLE_WORDCOMPLETION
 static int pletion_x = 0;
 		/* The x position in pletion_line of the last found completion. */
@@ -1412,13 +1407,6 @@ void update_undo(undo_type action)
 #endif /* !NANO_TINY */
 
 #ifdef ENABLE_WRAPPING
-/* Unset the prepend_wrap flag.  We need to do this as soon as we do
- * something other than type text. */
-void wrap_reset(void)
-{
-	prepend_wrap = FALSE;
-}
-
 /* When the current line is overlong, hard-wrap it at the furthest possible
  * whitespace character, and (if possible) prepend the remainder of the line
  * to the next line.  Return TRUE if wrapping occurred, and FALSE otherwise. */
@@ -1466,7 +1454,8 @@ bool do_wrap(void)
 	/* When prepending and the remainder of this line will not make the next
 	 * line too long, then join the two lines, so that, after the line wrap,
 	 * the remainder will effectively have been prefixed to the next line. */
-	if (prepend_wrap && rest_length + strlenpt(line->next->data) <= wrap_at) {
+	if (openfile->spillage_line && openfile->spillage_line == line->next &&
+				rest_length + strlenpt(line->next->data) <= wrap_at) {
 		/* Go to the end of this line. */
 		openfile->current_x = line_len;
 
@@ -1511,14 +1500,13 @@ bool do_wrap(void)
 	/* Now split the line. */
 	do_enter();
 
+	openfile->spillage_line = openfile->current;
+
 	if (cursor_x < wrap_loc) {
 		openfile->current = openfile->current->prev;
 		openfile->current_x = cursor_x;
-		prepend_wrap = TRUE;
-	} else {
+	} else
 		openfile->current_x += (cursor_x - wrap_loc);
-		prepend_wrap = FALSE;
-	}
 
 	openfile->placewewant = xplustabs();