Add a -S flag to new-window to make it select the existing window if one

with the given name already exists rather than failing with an error.
Also add a format to check if a window or session name exists which
allows the same with other commands. Requested by and discussed with
kn@.

cmd-new-window.c

@@ -38,8 +38,8 @@ const struct cmd_entry cmd_new_window_entry = {
 	.name = "new-window",
 	.alias = "neww",
 
-	.args = { "abc:de:F:kn:Pt:", 0, -1 },
-	.usage = "[-abdkP] [-c start-directory] [-e environment] [-F format] "
+	.args = { "abc:de:F:kn:PSt:", 0, -1 },
+	.usage = "[-abdkPS] [-c start-directory] [-e environment] [-F format] "
 		 "[-n window-name] " CMD_TARGET_WINDOW_USAGE " [command]",
 
 	.target = { 't', CMD_FIND_WINDOW, CMD_FIND_WINDOW_INDEX },
@@ -52,6 +52,7 @@ static enum cmd_retval
 cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 {
 	struct args		*args = cmd_get_args(self);
+	struct client		*c = cmdq_get_client(item);
 	struct cmd_find_state	*current = cmdq_get_current(item);
 	struct cmd_find_state	*target = cmdq_get_target(item);
 	struct spawn_context	 sc;
@@ -59,12 +60,41 @@ cmd_new_window_exec(struct cmd *self, struct cmdq_item *item)
 	struct session		*s = target->s;
 	struct winlink		*wl = target->wl;
 	int			 idx = target->idx, before;
-	struct winlink		*new_wl;
+	struct winlink		*new_wl = NULL;
 	char			*cause = NULL, *cp;
-	const char		*template, *add;
+	const char		*template, *add, *name;
 	struct cmd_find_state	 fs;
 	struct args_value	*value;
 
+	/*
+	 * If -S and -n are given and -t is not and a single window with this
+	 * name already exists, select it.
+	 */
+	name = args_get(args, 'n');
+	if (args_has(args, 'S') && name != NULL && target->idx == -1) {
+		RB_FOREACH(wl, winlinks, &s->windows) {
+			if (strcmp(wl->window->name, name) != 0)
+				continue;
+			if (new_wl == NULL) {
+				new_wl = wl;
+				continue;
+			}
+			cmdq_error(item, "multiple windows named %s", name);
+			return (CMD_RETURN_ERROR);
+		}
+		if (new_wl != NULL) {
+			if (args_has(args, 'd'))
+				return (CMD_RETURN_NORMAL);
+			if (session_set_current(s, new_wl) == 0)
+				server_redraw_session(s);
+			if (c != NULL && c->session != NULL)
+				s->curw->window->latest = c;
+			recalculate_sizes();
+			return (CMD_RETURN_NORMAL);
+		}
+	}
+
+
 	before = args_has(args, 'b');
 	if (args_has(args, 'a') || before) {
 		idx = winlink_shuffle_up(s, wl, before);

format.c

@@ -100,6 +100,8 @@ format_job_cmp(struct format_job *fj1, struct format_job *fj2)
 #define FORMAT_LENGTH 0x800
 #define FORMAT_WIDTH 0x1000
 #define FORMAT_QUOTE_STYLE 0x2000
+#define FORMAT_WINDOW_NAME 0x4000
+#define FORMAT_SESSION_NAME 0x8000
 
 /* Limit on recursion. */
 #define FORMAT_LOOP_LIMIT 10
@@ -1733,7 +1735,7 @@ format_build_modifiers(struct format_expand_state *es, const char **s,
 		}
 
 		/* Now try single character with arguments. */
-		if (strchr("mCst=peq", cp[0]) == NULL)
+		if (strchr("mCNst=peq", cp[0]) == NULL)
 			break;
 		c = cp[0];
 
@@ -1857,6 +1859,24 @@ format_search(struct format_modifier *fm, struct window_pane *wp, const char *s)
 	return (value);
 }
 
+/* Does session name exist? */
+static char *
+format_session_name(struct format_expand_state *es, const char *fmt)
+{
+	char		*name;
+	struct session	*s;
+
+	name = format_expand1(es, fmt);
+	RB_FOREACH(s, sessions, &sessions) {
+		if (strcmp(s->name, name) == 0) {
+			free(name);
+			return (xstrdup("1"));
+		}
+	}
+	free(name);
+	return (xstrdup("0"));
+}
+
 /* Loop over sessions. */
 static char *
 format_loop_sessions(struct format_expand_state *es, const char *fmt)
@@ -1892,6 +1912,30 @@ format_loop_sessions(struct format_expand_state *es, const char *fmt)
 	return (value);
 }
 
+/* Does window name exist? */
+static char *
+format_window_name(struct format_expand_state *es, const char *fmt)
+{
+	struct format_tree	*ft = es->ft;
+	char			*name;
+	struct winlink		*wl;
+
+	if (ft->s == NULL) {
+		format_log(es, "window name but no session");
+		return (NULL);
+	}
+
+	name = format_expand1(es, fmt);
+	RB_FOREACH(wl, winlinks, &ft->s->windows) {
+		if (strcmp(wl->window->name, name) == 0) {
+			free(name);
+			return (xstrdup("1"));
+		}
+	}
+	free(name);
+	return (xstrdup("0"));
+}
+
 /* Loop over windows. */
 static char *
 format_loop_windows(struct format_expand_state *es, const char *fmt)
@@ -2251,6 +2295,13 @@ format_replace(struct format_expand_state *es, const char *key, size_t keylen,
 			case 'T':
 				modifiers |= FORMAT_EXPANDTIME;
 				break;
+			case 'N':
+				if (fm->argc < 1 ||
+				    strchr(fm->argv[0], 'w') != NULL)
+					modifiers |= FORMAT_WINDOW_NAME;
+				else if (strchr(fm->argv[0], 's') != NULL)
+					modifiers |= FORMAT_SESSION_NAME;
+				break;
 			case 'S':
 				modifiers |= FORMAT_SESSIONS;
 				break;
@@ -2291,6 +2342,14 @@ format_replace(struct format_expand_state *es, const char *key, size_t keylen,
 		value = format_loop_panes(es, copy);
 		if (value == NULL)
 			goto fail;
+	} else if (modifiers & FORMAT_WINDOW_NAME) {
+		value = format_window_name(es, copy);
+		if (value == NULL)
+			goto fail;
+	} else if (modifiers & FORMAT_SESSION_NAME) {
+		value = format_session_name(es, copy);
+		if (value == NULL)
+			goto fail;
 	} else if (search != NULL) {
 		/* Search in pane. */
 		new = format_expand1(es, copy);

tmux.1

@@ -2348,7 +2348,7 @@ the
 .Ic base-index
 option.
 .It Xo Ic new-window
-.Op Fl abdkP
+.Op Fl abdkPS
 .Op Fl c Ar start-directory
 .Op Fl e Ar environment
 .Op Fl F Ar format
@@ -2377,6 +2377,14 @@ represents the window to be created; if the target already exists an error is
 shown, unless the
 .Fl k
 flag is used, in which case it is destroyed.
+If
+.Fl S
+is given and a window named
+.Ar window-name
+already exists, it is selected (unless
+.Fl d
+is also given in which case the command does nothing).
+.Pp
 .Ar shell-command
 is the command to execute.
 If
@@ -4688,6 +4696,17 @@ For example, to get a list of windows formatted like the status line:
 #{W:#{E:window-status-format} ,#{E:window-status-current-format} }
 .Ed
 .Pp
+.Ql N:\&
+checks if a window (without any suffix or with the
+.Ql w
+suffix) or a session (with the
+.Ql s
+suffix) name exists, for example
+.Ql `N/w:foo`
+is replaced with 1 if a window named
+.Ql foo
+exists.
+.Pp
 A prefix of the form
 .Ql s/foo/bar/:\&
 will substitute