Add -n and -p flags to switch-client to move to the next and previous

session (yes, it doesn't match window/pane, but so what, nor does
switch-client).

Based on a diff long ago from "edsouza".

cmd-switch-client.c

@@ -27,6 +27,7 @@
  * Switch client to a different session.
  */
 
+void	cmd_switch_client_init(struct cmd *, int);
 int	cmd_switch_client_parse(struct cmd *, int, char **, char **);
 int	cmd_switch_client_exec(struct cmd *, struct cmd_ctx *);
 void	cmd_switch_client_free(struct cmd *);
@@ -35,28 +36,50 @@ size_t	cmd_switch_client_print(struct cmd *, char *, size_t);
 struct cmd_switch_client_data {
 	char	*name;
 	char	*target;
+	int	 flag_next;
+	int	 flag_previous;
 };
 
 const struct cmd_entry cmd_switch_client_entry = {
 	"switch-client", "switchc",
-	"[-c target-client] [-t target-session]",
+	"[-np] [-c target-client] [-t target-session]",
 	0, "",
-	NULL,
+	cmd_switch_client_init,
 	cmd_switch_client_parse,
 	cmd_switch_client_exec,
 	cmd_switch_client_free,
 	cmd_switch_client_print
 };
 
+void
+cmd_switch_client_init(struct cmd *self, int key)
+{
+	struct cmd_switch_client_data	*data;
+
+	self->data = data = xmalloc(sizeof *data);
+	data->name = NULL;
+	data->target = NULL;
+	data->flag_next = 0;
+	data->flag_previous = 0;
+
+	switch (key) {
+	case '(':
+		data->flag_previous = 1;
+		break;
+	case ')':
+		data->flag_next = 1;
+		break;
+	}
+}
+
 int
 cmd_switch_client_parse(struct cmd *self, int argc, char **argv, char **cause)
 {
 	struct cmd_switch_client_data	*data;
 	int				 opt;
 
-	self->data = data = xmalloc(sizeof *data);
-	data->name = NULL;
-	data->target = NULL;
+	self->entry->init(self, KEYC_NONE);
+	data = self->data;
 
 	while ((opt = getopt(argc, argv, "c:t:")) != -1) {
 		switch (opt) {
@@ -65,9 +88,21 @@ cmd_switch_client_parse(struct cmd *self, int argc, char **argv, char **cause)
 				data->name = xstrdup(optarg);
 			break;
 		case 't':
+			if (data->flag_next || data->flag_previous)
+				goto usage;
 			if (data->target == NULL)
 				data->target = xstrdup(optarg);
 			break;
+		case 'n':
+			if (data->flag_previous || data->target != NULL)
+				goto usage;
+			data->flag_next = 1;
+			break;
+		case 'p':
+			if (data->flag_next || data->target != NULL)
+				goto usage;
+			data->flag_next = 1;
+			break;
 		default:
 			goto usage;
 		}
@@ -98,9 +133,22 @@ cmd_switch_client_exec(struct cmd *self, struct cmd_ctx *ctx)
 
 	if ((c = cmd_find_client(ctx, data->name)) == NULL)
 		return (-1);
-	if ((s = cmd_find_session(ctx, data->target)) == NULL)
-		return (-1);
 
+	if (data->flag_next) {
+		if ((s = session_next_session(c->session)) == NULL) {
+			ctx->error(ctx, "can't find next session");
+			return (-1);
+		}
+	} else if (data->flag_previous) {
+		if ((s = session_previous_session(c->session)) == NULL) {
+			ctx->error(ctx, "can't find previous session");
+			return (-1);
+		}
+	} else
+		s = cmd_find_session(ctx, data->target);
+
+	if (s == NULL)
+		return (-1);
 	c->session = s;
 
 	recalculate_sizes();
@@ -130,6 +178,10 @@ cmd_switch_client_print(struct cmd *self, char *buf, size_t len)
 	off += xsnprintf(buf, len, "%s", self->entry->name);
 	if (data == NULL)
 		return (off);
+	if (off < len && data->flag_next)
+		off += xsnprintf(buf + off, len - off, "%s", " -n");
+	if (off < len && data->flag_previous)
+		off += xsnprintf(buf + off, len - off, "%s", " -p");
 	if (off < len && data->name != NULL)
 		off += cmd_prarg(buf + off, len - off, " -c ", data->name);
 	if (off < len && data->target != NULL)

key-bindings.c

@@ -108,6 +108,8 @@ key_bindings_init(void)
 		{ '#', 			  0, &cmd_list_buffers_entry },
 		{ '%', 			  0, &cmd_split_window_entry },
 		{ '&', 			  0, &cmd_confirm_before_entry },
+		{ '(',                    0, &cmd_switch_client_entry },
+		{ ')',                    0, &cmd_switch_client_entry },
 		{ ',', 			  0, &cmd_command_prompt_entry },
 		{ '-', 			  0, &cmd_delete_buffer_entry },
 		{ '.', 			  0, &cmd_command_prompt_entry },

session.c

@@ -169,6 +169,48 @@ session_index(struct session *s, u_int *i)
 	return (-1);
 }
 
+/* Find the next usable session. */
+struct session *
+session_next_session(struct session *s)
+{
+	struct session *s2;
+	u_int		i;
+
+	if (ARRAY_LENGTH(&sessions) == 0 || session_index(s, &i) != 0)
+		return (NULL);
+
+	do {
+		if (i == ARRAY_LENGTH(&sessions) - 1)
+			i = 0;
+		else
+			i++;
+		s2 = ARRAY_ITEM(&sessions, i);
+	} while (s2 == NULL || s2->flags & SESSION_DEAD);
+
+	return (s2);
+}
+
+/* Find the previous usable session. */
+struct session *
+session_previous_session(struct session *s)
+{
+	struct session *s2;
+	u_int		i;
+
+	if (ARRAY_LENGTH(&sessions) == 0 || session_index(s, &i) != 0)
+		return (NULL);
+
+	do {
+		if (i == 0)
+			i = ARRAY_LENGTH(&sessions) - 1;
+		else
+			i--;
+		s2 = ARRAY_ITEM(&sessions, i);
+	} while (s2 == NULL || s2->flags & SESSION_DEAD);
+
+	return (s2);
+}
+
 /* Create a new window on a session. */
 struct winlink *
 session_new(struct session *s,

tmux.1

@@ -660,6 +660,7 @@ Suspend a client by sending
 .Dv SIGTSTP
 (tty stop).
 .It Xo Ic switch-client
+.Op Fl np
 .Op Fl c Ar target-client
 .Op Fl t Ar target-session
 .Xc
@@ -668,6 +669,11 @@ Switch the current session for client
 .Ar target-client
 to
 .Ar target-session .
+If
+.Fl n
+or
+.Fl p
+is used, the client is moved to the next or previous session respectively.
 .El
 .Sh WINDOWS AND PANES
 A

tmux.h

@@ -1965,6 +1965,8 @@ struct session	*session_create(const char *, const char *, const char *,
 		     char **);
 void		 session_destroy(struct session *);
 int		 session_index(struct session *, u_int *);
+struct session	*session_next_session(struct session *);
+struct session	*session_previous_session(struct session *);
 struct winlink	*session_new(struct session *,
 		     const char *, const char *, const char *, int, char **);
 struct winlink	*session_attach(