new feature: a bindable 'zap', to erase text without changing cutbuffer

This function allows the user to "make space": annihilating lines or
regions while keeping intact for pasting the stuff in the cutbuffer
that was cut or copied earlier.

Signed-off-by: Brand Huntsman <alpha@qzx.com>

doc/nano.texi

@@ -1150,6 +1150,9 @@ Pastes the currently stored text into the current buffer at the
 current cursor position.
 (The old form 'uncut' is deprecated.)
 
+@item zap
+Throw away the current line (or the marked region).
+
 @item cutwordleft
 Cuts from the cursor position to the beginning of the preceding word.
 (This function is not bound by default.  If your terminal produces

doc/nanorc.5

@@ -506,6 +506,9 @@ Pastes the currently stored text into the current buffer at the
 current cursor position.
 (The old form 'uncut' is deprecated.)
 .TP
+.B zap
+Throw away the current line (or the marked region).
+.TP
 .B cutwordleft
 Cuts from the cursor position to the beginning of the preceding word.
 (This function is not bound by default.  If your terminal produces

src/cut.c

@@ -104,8 +104,9 @@ void cut_to_eof(void)
 /* Move text from the current buffer into the cutbuffer.  If
  * copy_text is TRUE, copy the text back into the buffer afterward.
  * If cut_till_eof is TRUE, move all text from the current cursor
- * position to the end of the file into the cutbuffer. */
-void do_cut_text(bool copy_text, bool marked, bool cut_till_eof)
+ * position to the end of the file into the cutbuffer.  If append
+ * is TRUE (when zapping), always append the cut to the cutbuffer. */
+void do_cut_text(bool copy_text, bool marked, bool cut_till_eof, bool append)
 {
 #ifndef NANO_TINY
 	filestruct *cb_save = NULL;
@@ -120,7 +121,7 @@ void do_cut_text(bool copy_text, bool marked, bool cut_till_eof)
 	size_t was_totsize = openfile->totsize;
 
 	/* If cuts were not continuous, or when cutting a region, clear the slate. */
-	if (!keep_cutbuffer || marked || cut_till_eof) {
+	if (!append && (!keep_cutbuffer || marked || cut_till_eof)) {
 		free_filestruct(cutbuffer);
 		cutbuffer = NULL;
 		/* After a line cut, future line cuts should add to the cutbuffer. */
@@ -193,10 +194,10 @@ void do_cut_text_void(void)
 			openfile->current_undo->mark_begin_lineno != openfile->current->lineno ||
 			!keep_cutbuffer)
 		add_undo(CUT);
-	do_cut_text(FALSE, openfile->mark, FALSE);
+	do_cut_text(FALSE, openfile->mark, FALSE, FALSE);
 	update_undo(CUT);
 #else
-	do_cut_text(FALSE, FALSE, FALSE);
+	do_cut_text(FALSE, FALSE, FALSE, FALSE);
 #endif
 }
 
@@ -218,7 +219,7 @@ void do_copy_text(void)
 	if (mark_is_set || openfile->current != next_contiguous_line)
 		cutbuffer_reset();
 
-	do_cut_text(TRUE, mark_is_set, FALSE);
+	do_cut_text(TRUE, mark_is_set, FALSE, FALSE);
 
 	/* If the mark was set, blow away the cutbuffer on the next copy. */
 	next_contiguous_line = (mark_is_set ? NULL : openfile->current);
@@ -236,9 +237,35 @@ void do_copy_text(void)
 void do_cut_till_eof(void)
 {
 	add_undo(CUT_TO_EOF);
-	do_cut_text(FALSE, FALSE, TRUE);
+	do_cut_text(FALSE, FALSE, TRUE, FALSE);
 	update_undo(CUT_TO_EOF);
 }
+
+/* Erase text (current line or marked region), sending it into oblivion. */
+void zap_text(void)
+{
+	/* Remember the current cutbuffer so it can be restored after the zap. */
+	filestruct *was_cutbuffer = cutbuffer;
+	filestruct *was_cutbottom = cutbottom;
+
+	/* Add a new undo item only when the current item is not a ZAP or when
+	 * the current zap is not contiguous with the previous zapping. */
+	if (openfile->last_action != ZAP || openfile->current_undo == NULL ||
+			openfile->current_undo->mark_begin_lineno != openfile->current->lineno ||
+			openfile->current_undo->xflags & (MARK_WAS_SET|WAS_MARKED_FORWARD))
+		add_undo(ZAP);
+
+	/* Use the cutbuffer from the ZAP undo item, so the cut can be undone. */
+	cutbuffer = openfile->current_undo->cutbuffer;
+	cutbottom = openfile->current_undo->cutbottom;
+
+	do_cut_text(FALSE, openfile->mark, FALSE, TRUE);
+
+	update_undo(ZAP);
+
+	cutbuffer = was_cutbuffer;
+	cutbottom = was_cutbottom;
+}
 #endif /* !NANO_TINY */
 
 /* Copy text from the cutbuffer into the current buffer. */

src/files.c

@@ -533,7 +533,7 @@ void replace_buffer(const char *filename)
 #ifndef NANO_TINY
 	add_undo(CUT_TO_EOF);
 #endif
-	do_cut_text(FALSE, FALSE, TRUE);
+	do_cut_text(FALSE, FALSE, TRUE, FALSE);
 #ifndef NANO_TINY
 	update_undo(CUT_TO_EOF);
 #endif
@@ -574,7 +574,7 @@ void replace_marked_buffer(const char *filename)
 	/* Throw away the text under the mark. */
 	cutbuffer = NULL;
 	add_undo(CUT);
-	do_cut_text(FALSE, TRUE, FALSE);
+	do_cut_text(FALSE, TRUE, FALSE, FALSE);
 	update_undo(CUT);
 	free_filestruct(cutbuffer);
 	cutbuffer = was_cutbuffer;

src/global.c

@@ -576,6 +576,7 @@ void shortcut_init(void)
 	const char *mark_gist = N_("Mark text starting from the cursor position");
 	const char *copy_gist =
 		N_("Copy current line (or marked region) and store it in cutbuffer");
+	const char *zap_gist = N_("Throw away the current line (or marked region)");
 	const char *indent_gist = N_("Indent the current line (or marked lines)");
 	const char *unindent_gist = N_("Unindent the current line (or marked lines)");
 	const char *undo_gist = N_("Undo the last operation");
@@ -988,6 +989,9 @@ void shortcut_init(void)
 	add_to_funcs(run_macro, MMAIN,
 		N_("Run Macro"), WITHORSANS(runmacro_gist), BLANKAFTER, VIEW);
 
+	add_to_funcs(zap_text, MMAIN,
+		N_("Zap Text"), WITHORSANS(zap_gist), BLANKAFTER, NOVIEW);
+
 #ifdef ENABLE_COLOR
 	if (!ISSET(RESTRICTED))
 		add_to_funcs(do_linter, MMAIN,
@@ -1471,6 +1475,8 @@ sc *strtosc(const char *input)
 	else if (!strcasecmp(input, "copy") ||
 			 !strcasecmp(input, "copytext"))  /* Deprecated.  Remove end of 2018. */
 		s->func = do_copy_text;
+	else if (!strcasecmp(input, "zap"))
+		s->func = zap_text;
 	else if (!strcasecmp(input, "mark"))
 		s->func = do_mark;
 #endif

src/nano.h

@@ -178,7 +178,7 @@ typedef enum {
 #ifdef ENABLE_COMMENT
 	COMMENT, UNCOMMENT, PREFLIGHT,
 #endif
-	CUT, CUT_TO_EOF, PASTE, INSERT, COUPLE_BEGIN, COUPLE_END, OTHER
+	ZAP, CUT, CUT_TO_EOF, PASTE, INSERT, COUPLE_BEGIN, COUPLE_END, OTHER
 } undo_type;
 
 /* Structure types. */

src/proto.h

@@ -249,11 +249,12 @@ void cutbuffer_reset(void);
 #ifndef NANO_TINY
 void cut_marked(bool *right_side_up);
 #endif
-void do_cut_text(bool copy_text, bool marked, bool cut_till_eof);
+void do_cut_text(bool copy_text, bool marked, bool cut_till_eof, bool append);
 void do_cut_text_void(void);
 #ifndef NANO_TINY
 void do_copy_text(void);
 void do_cut_till_eof(void);
+void zap_text(void);
 #endif
 void do_uncut_text(void);
 

src/text.c

@@ -687,7 +687,7 @@ void redo_cut(undo *u)
 	openfile->mark = fsfromline(u->mark_begin_lineno);
 	openfile->mark_x = (u->xflags == WAS_WHOLE_LINE) ? 0 : u->mark_begin_x;
 
-	do_cut_text(FALSE, TRUE, FALSE);
+	do_cut_text(FALSE, TRUE, FALSE, u->type == ZAP);
 
 	free_filestruct(cutbuffer);
 	cutbuffer = oldcutbuffer;
@@ -792,6 +792,10 @@ void do_undo(void)
 		undidmsg = _("text add");
 		break;
 #endif
+	case ZAP:
+		undidmsg = _("erasure");
+		undo_cut(u);
+		break;
 	case CUT_TO_EOF:
 	case CUT:
 		undidmsg = _("text cut");
@@ -968,6 +972,10 @@ void do_redo(void)
 		redidmsg = _("text add");
 		break;
 #endif
+	case ZAP:
+		redidmsg = _("erasure");
+		redo_cut(u);
+		break;
 	case CUT_TO_EOF:
 	case CUT:
 		redidmsg = _("text cut");
@@ -1201,7 +1209,7 @@ bool execute_command(const char *command)
 		if (ISSET(MULTIBUFFER)) {
 			switch_to_prev_buffer();
 			if (openfile->mark)
-				do_cut_text(TRUE, TRUE, FALSE);
+				do_cut_text(TRUE, TRUE, FALSE, FALSE);
 		} else
 #endif
 		{
@@ -1212,7 +1220,7 @@ bool execute_command(const char *command)
 				openfile->current_x = 0;
 			}
 			add_undo(CUT);
-			do_cut_text(FALSE, openfile->mark, openfile->mark == NULL);
+			do_cut_text(FALSE, openfile->mark, openfile->mark == NULL, FALSE);
 			update_undo(CUT);
 		}
 
@@ -1403,6 +1411,7 @@ void add_undo(undo_type action)
 #endif
 	case CUT_TO_EOF:
 		break;
+	case ZAP:
 	case CUT:
 		if (openfile->mark) {
 			u->mark_begin_lineno = openfile->mark->lineno;
@@ -1529,12 +1538,17 @@ void update_undo(undo_type action)
 	case SPLIT_END:
 		break;
 #endif
+	case ZAP:
 	case CUT_TO_EOF:
 	case CUT:
 		if (!cutbuffer)
 			break;
-		free_filestruct(u->cutbuffer);
-		u->cutbuffer = copy_filestruct(cutbuffer);
+		if (u->type == ZAP)
+			u->cutbuffer = cutbuffer;
+		else {
+			free_filestruct(u->cutbuffer);
+			u->cutbuffer = copy_filestruct(cutbuffer);
+		}
 		if (u->xflags == MARK_WAS_SET) {
 			/* If the "marking" operation was from right-->left or
 			 * bottom-->top, then swap the mark points. */