new feature: allow binding a key to a string (in a nanorc file)

In this way a single keystroke can produce a fragment of text or a
series of commands, or a mix of the two.  It is like a prerecorded
macro.

This fulfills https://savannah.gnu.org/bugs/?52931.

src/global.c

@@ -318,6 +318,9 @@ void flip_newbuffer(void)
 void discard_buffer(void)
 {
 }
+void implant(void)
+{
+}
 
 /* Add a function to the function list. */
 void add_to_funcs(void (*func)(void), int menus, const char *desc, const char *help,
@@ -1379,6 +1382,17 @@ void set_spell_shortcuts(void)
 }
 #endif /* ENABLE_COLOR && ENABLE_SPELLER */
 
+/* Execute the function of the given shortcut. */
+void execute(const sc *shortcut)
+{
+	if (shortcut->scfunc == implant)
+		/* Insert the corresponding string into the keyboard buffer. */
+		for (int i = strlen(shortcut->expansion); i > 0; i--)
+			put_back(shortcut->expansion[i - 1]);
+	else
+		shortcut->scfunc();
+}
+
 const subnfunc *sctofunc(const sc *s)
 {
 	subnfunc *f = allfuncs;

src/nano.c

@@ -1753,7 +1753,8 @@ int do_input(bool allow_funcs)
 			}
 #endif
 			/* Execute the function of the shortcut. */
-			s->scfunc();
+			execute(s);
+
 #ifndef NANO_TINY
 			/* When the marked region changes without Shift being held,
 			 * discard a soft mark.  And when the marked region covers a

src/nano.h

@@ -439,6 +439,8 @@ typedef struct sc {
 	int ordinal;
 		/* The how-manieth toggle this is, in order to be able to
 		 * keep them in sequence. */
+	char *expansion;
+		/* The string of keycodes to which this shortcut is expanded. */
 #endif
 	struct sc *next;
 		/* Next in the list. */

src/prompt.c

@@ -180,7 +180,7 @@ int do_statusbar_input(bool *ran_func, bool *finished)
 				*ran_func = TRUE;
 				if (f && (!ISSET(VIEW_MODE) || f->viewok) &&
 								f->scfunc != do_gotolinecolumn_void)
-					f->scfunc();
+					execute(s);
 			}
 			*finished = TRUE;
 		}

src/proto.h

@@ -318,6 +318,7 @@ char *input_tab(char *buf, bool allow_files, size_t *place,
 
 /* Some functions in global.c. */
 size_t length_of_list(int menu);
+void implant(void);
 const sc *first_sc_for(int menu, void (*func)(void));
 int the_code_for(void (*func)(void), int defaultval);
 functionptrtype func_from_key(int *kbinput);
@@ -329,6 +330,7 @@ void shortcut_init(void);
 void set_lint_or_format_shortcuts(void);
 void set_spell_shortcuts(void);
 #endif
+void execute(const sc *shortcut);
 const subnfunc *sctofunc(const sc *s);
 const char *flagtostr(int flag);
 sc *strtosc(const char *input);
@@ -619,6 +621,7 @@ void dump_filestruct(const filestruct *inptr);
 void record_macro(void);
 void run_macro(void);
 size_t get_key_buffer_len(void);
+void put_back(int keycode);
 void unget_kbinput(int kbinput, bool metakey);
 int get_kbinput(WINDOW *win, bool showcursor);
 int parse_kbinput(WINDOW *win);

src/rcfile.c

@@ -336,6 +336,7 @@ bool is_universal(void (*func)(void))
 		func == do_home || func == do_end ||
 #ifndef NANO_TINY
 		func == do_prev_word_void || func == do_next_word_void ||
+		func == implant ||
 #endif
 		func == do_delete || func == do_backspace ||
 		func == do_cut_text_void || func == do_uncut_text ||
@@ -396,7 +397,7 @@ void parse_binding(char *ptr, bool dobind)
 
 	if (dobind) {
 		funcptr = ptr;
-		ptr = parse_next_word(ptr);
+		ptr = parse_argument(ptr);
 
 		if (funcptr[0] == '\0') {
 			rcfile_error(N_("Must specify a function to bind the key to"));
@@ -414,7 +415,16 @@ void parse_binding(char *ptr, bool dobind)
 	}
 
 	if (dobind) {
-		newsc = strtosc(funcptr);
+		/* If the thing to bind starts with a double quote, it is a string,
+		 * otherwise it is the name of a function. */
+		if (*funcptr == '"') {
+			newsc = nmalloc(sizeof(sc));
+			newsc->scfunc = implant;
+			newsc->expansion = mallocstrcpy(NULL, funcptr + 1);
+			newsc->toggle = 0;
+		} else
+		    newsc = strtosc(funcptr);
+
 		if (newsc == NULL) {
 			rcfile_error(N_("Cannot map name \"%s\" to a function"), funcptr);
 			goto free_things;