options: add --zap, that makes <Bsp> and <Del> erase a marked region

Using --zap or -Z on the command line, or 'set zap' in a nanorc file,
makes the <Bsp> and <Del> keys erase selected text (a marked region)
as they do in some other editors, and without affecting the cutbuffer.

This fulfills https://savannah.gnu.org/bugs/?54837.
Requested-by: Liu Hao <lh_mouse@126.com>

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

doc/nano.1

@@ -167,6 +167,10 @@ should be considered as part of a word.  This overrides option
 Specify the name of the syntax highlighting to use from among the ones
 defined in the \fInanorc\fP files.
 .TP
+.BR \-Z ", " \-\-zap
+Let an unmodified Backspace or Delete erase the marked region
+(instead of a single character, and without affecting the cutbuffer).
+.TP
 .BR \-a ", " \-\-atblanks
 When doing soft line wrapping, wrap lines at whitespace
 instead of always at the edge of the screen.

doc/nano.texi

@@ -270,6 +270,11 @@ should be considered as parts of words.  This overrides option
 Specify the syntax to be used for highlighting.
 @xref{Syntax Highlighting} for more info.
 
+@item -Z
+@itemx --zap
+Let an unmodified @key{Backspace} or @key{Delete} erase the marked region
+(instead of a single character, and without affecting the cutbuffer).
+
 @item -a
 @itemx --atblanks
 When doing soft line wrapping, wrap lines at whitespace
@@ -932,6 +937,10 @@ Specify which other characters (besides the normal alphanumeric ones)
 should be considered as parts of words.  This overrides the option
 @code{wordbounds}.
 
+@item set zap
+Let an unmodified @key{Backspace} or @key{Delete} erase the marked region
+(instead of a single character, and without affecting the cutbuffer).
+
 @end table
 
 @node Syntax Highlighting

doc/nanorc.5

@@ -297,6 +297,10 @@ characters as parts of words.
 Specify which other characters (besides the normal alphanumeric ones)
 should be considered as parts of words.  This overrides the option
 \fBwordbounds\fR.
+.TP
+.B set zap
+Let an unmodified Backspace or Delete erase the marked region
+(instead of a single character, and without affecting the cutbuffer).
 
 .SH SYNTAX HIGHLIGHTING
 Coloring the different syntactic elements of a file

doc/sample.nanorc.in

@@ -194,6 +194,9 @@
 ## set, it overrides option 'set wordbounds'.
 # set wordchars "<_>."
 
+## Let an unmodified Backspace or Delete erase the marked region (instead
+## of a single character, and without affecting the cutbuffer).
+# set zap
 
 ## Paint the interface elements of nano.  These are examples;
 ## by default there are no colors, except for errorcolor.

src/nano.c

@@ -845,6 +845,7 @@ void usage(void)
 					N_("Syntax definition to use for coloring"));
 #endif
 #ifndef NANO_TINY
+	print_opt("-Z", "--zap", N_("Let Bsp and Del erase a marked region"));
 	print_opt("-a", "--atblanks", N_("When soft-wrapping, do it at whitespace"));
 #endif
 	print_opt("-c", "--constantshow", N_("Constantly show cursor position"));
@@ -2020,6 +2021,7 @@ int main(int argc, char **argv)
 		{"smooth", 0, NULL, 'S'},
 		{"wordbounds", 0, NULL, 'W'},
 		{"wordchars", 1, NULL, 'X'},
+		{"zap", 0, NULL, 'Z'},
 		{"atblanks", 0, NULL, 'a'},
 		{"autoindent", 0, NULL, 'i'},
 		{"cutfromcursor", 0, NULL, 'k'},
@@ -2083,7 +2085,7 @@ int main(int argc, char **argv)
 
 	while ((optchr =
 		getopt_long(argc, argv,
-				"ABC:DEFGHIKLMNOPQ:RST:UVWX:Y:abcdefghijklmno:pqr:s:tuvwxyz$",
+				"ABC:DEFGHIKLMNOPQ:RST:UVWX:Y:Zabcdefghijklmno:pqr:s:tuvwxyz$",
 				long_options, NULL)) != -1) {
 		switch (optchr) {
 #ifndef NANO_TINY
@@ -2189,6 +2191,9 @@ int main(int argc, char **argv)
 				break;
 #endif
 #ifndef NANO_TINY
+			case 'Z':
+				SET(LET_THEM_ZAP);
+				break;
 			case 'a':
 				SET(AT_BLANKS);
 				break;

src/nano.h

@@ -540,7 +540,8 @@ enum
 	LINE_NUMBERS,
 	NO_PAUSES,
 	AT_BLANKS,
-	AFTER_ENDS
+	AFTER_ENDS,
+	LET_THEM_ZAP
 };
 
 /* Flags for the menus in which a given function should be present. */

src/rcfile.c

@@ -112,6 +112,7 @@ static const rcoption rcopts[] = {
 	{"whitespace", 0},
 	{"wordbounds", WORD_BOUNDS},
 	{"wordchars", 0},
+	{"zap", LET_THEM_ZAP},
 #endif
 #ifdef ENABLE_COLOR
 	{"titlecolor", 0},

src/text.c

@@ -183,6 +183,11 @@ void do_deletion(undo_type action)
 /* Delete the character under the cursor. */
 void do_delete(void)
 {
+#ifndef NANO_TINY
+	if (openfile->mark && ISSET(LET_THEM_ZAP))
+		zap_text();
+	else
+#endif
 	do_deletion(DEL);
 }
 
@@ -190,6 +195,11 @@ void do_delete(void)
  * character, and then delete the character under the cursor. */
 void do_backspace(void)
 {
+#ifndef NANO_TINY
+	if (openfile->mark && ISSET(LET_THEM_ZAP))
+		zap_text();
+	else
+#endif
 	if (openfile->current != openfile->fileage || openfile->current_x > 0) {
 		do_left();
 		do_deletion(BACK);

syntax/nanorc.nanorc

@@ -7,7 +7,7 @@ comment "#"
 icolor brightred "^[[:space:]]*((un)?(bind|set)|include|syntax|header|magic|comment|linter|i?color|extendsyntax).*"
 
 # Keywords
-icolor brightgreen "^[[:space:]]*(set|unset)[[:space:]]+(afterends|allow_insecure_backup|atblanks|autoindent|backup|backwards|boldtext|casesensitive|constantshow|cutfromcursor|fill[[:space:]]+-?[[:digit:]]+|historylog|linenumbers|locking|morespace|mouse|multibuffer|noconvert|nohelp|nopauses|nonewlines|nowrap|positionlog|preserve|quickblank|quiet|rebinddelete|rebindkeypad|regexp|showcursor|smarthome|smooth|softwrap|suspend|tabsize[[:space:]]+[1-9][0-9]*|tabstospaces|tempfile|trimblanks|unix|view|wordbounds)\>"
+icolor brightgreen "^[[:space:]]*(set|unset)[[:space:]]+(afterends|allow_insecure_backup|atblanks|autoindent|backup|backwards|boldtext|casesensitive|constantshow|cutfromcursor|fill[[:space:]]+-?[[:digit:]]+|historylog|linenumbers|locking|morespace|mouse|multibuffer|noconvert|nohelp|nopauses|nonewlines|nowrap|positionlog|preserve|quickblank|quiet|rebinddelete|rebindkeypad|regexp|showcursor|smarthome|smooth|softwrap|suspend|tabsize[[:space:]]+[1-9][0-9]*|tabstospaces|tempfile|trimblanks|unix|view|wordbounds|zap)\>"
 icolor yellow "^[[:space:]]*set[[:space:]]+((error|function|key|number|selected|status|title)color)[[:space:]]+(bright)?(white|black|red|blue|green|yellow|magenta|cyan|normal)?(,(white|black|red|blue|green|yellow|magenta|cyan|normal))?\>"
 icolor brightgreen "^[[:space:]]*set[[:space:]]+(backupdir|brackets|errorcolor|functioncolor|keycolor|matchbrackets|numbercolor|operatingdir|punct|quotestr|selectedcolor|speller|statuscolor|titlecolor|whitespace|wordchars)[[:space:]]+"
 icolor brightgreen "^[[:space:]]*bind[[:space:]]+((\^([[:alpha:]]|[]@\^_]|Space)|M-([[:alpha:]]|[]!"#$%&'()*+,./0-9:;<=>?@\^_`{|}~-]|Space))|F([1-9]|1[0-6])|Ins|Del)[[:space:]]+([[:alpha:]]+|".*")[[:space:]]+(all|main|search|replace(with)?|yesno|gotoline|writeout|insert|ext(ernal)?cmd|help|spell|linter|browser|whereisfile|gotodir)([[:space:]]+#|[[:space:]]*$)"