Use the existing code in format.c to add foramts for word and line at

cursor position in copy mode, from Anindya Mukherjee.

format.c

@@ -703,30 +703,19 @@ format_cb_cursor_character(struct format_tree *ft, struct format_entry *fe)
 		xasprintf(&fe->value, "%.*s", (int)gc.data.size, gc.data.data);
 }
 
-/* Callback for mouse_word. */
-static void
-format_cb_mouse_word(struct format_tree *ft, struct format_entry *fe)
+/* Return word at given coordinates. Caller frees. */
+char *
+format_grid_word(struct grid *gd, u_int x, u_int y)
 {
-	struct window_pane	*wp;
-	u_int			 x, y, end;
-	struct grid		*gd;
 	struct grid_line	*gl;
 	struct grid_cell	 gc;
 	const char		*ws;
 	struct utf8_data	*ud = NULL;
+	u_int			 end;
 	size_t			 size = 0;
 	int			 found = 0;
+	char			*s = NULL;
 
-	if (!ft->m.valid)
-		return;
-	wp = cmd_mouse_pane(&ft->m, NULL, NULL);
-	if (wp == NULL)
-		return;
-	if (!TAILQ_EMPTY (&wp->modes))
-		return;
-	if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
-		return;
-	gd = wp->base.grid;
 	ws = options_get_string(global_s_options, "word-separators");
 
 	y = gd->hsize + y;
@@ -779,21 +768,19 @@ format_cb_mouse_word(struct format_tree *ft, struct format_entry *fe)
 	}
 	if (size != 0) {
 		ud[size].size = 0;
-		fe->value = utf8_tocstr(ud);
+		s = utf8_tocstr(ud);
 		free(ud);
 	}
+	return (s);
 }
 
-/* Callback for mouse_line. */
+/* Callback for mouse_word. */
 static void
-format_cb_mouse_line(struct format_tree *ft, struct format_entry *fe)
+format_cb_mouse_word(struct format_tree *ft, struct format_entry *fe)
 {
 	struct window_pane	*wp;
 	u_int			 x, y;
-	struct grid		*gd;
-	struct grid_cell	 gc;
-	struct utf8_data	*ud = NULL;
-	size_t			 size = 0;
+	char			*s;
 
 	if (!ft->m.valid)
 		return;
@@ -804,7 +791,21 @@ format_cb_mouse_line(struct format_tree *ft, struct format_entry *fe)
 		return;
 	if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
 		return;
-	gd = wp->base.grid;
+
+	s = format_grid_word(wp->base.grid, x, y);
+	if (s != NULL)
+		fe->value = s;
+}
+
+/* Return line at given coordinates. Caller frees. */
+char *
+format_grid_line(struct grid *gd, u_int y)
+{
+	struct grid_cell	 gc;
+	struct utf8_data	*ud = NULL;
+	u_int			 x;
+	size_t			 size = 0;
+	char			*s = NULL;
 
 	y = gd->hsize + y;
 	for (x = 0; x < grid_line_length(gd, y); x++) {
@@ -817,9 +818,33 @@ format_cb_mouse_line(struct format_tree *ft, struct format_entry *fe)
 	}
 	if (size != 0) {
 		ud[size].size = 0;
-		fe->value = utf8_tocstr(ud);
+		s = utf8_tocstr(ud);
 		free(ud);
 	}
+	return (s);
+}
+
+/* Callback for mouse_line. */
+static void
+format_cb_mouse_line(struct format_tree *ft, struct format_entry *fe)
+{
+	struct window_pane	*wp;
+	u_int			 x, y;
+	char			*s;
+
+	if (!ft->m.valid)
+		return;
+	wp = cmd_mouse_pane(&ft->m, NULL, NULL);
+	if (wp == NULL)
+		return;
+	if (!TAILQ_EMPTY (&wp->modes))
+		return;
+	if (cmd_mouse_at(wp, &ft->m, &x, &y, 0) != 0)
+		return;
+
+	s = format_grid_line(wp->base.grid, y);
+	if (s != NULL)
+		fe->value = s;
 }
 
 /* Merge a format tree. */

tmux.1

@@ -4214,6 +4214,8 @@ The following variables are available, where appropriate:
 .It Li "command_list_alias" Ta "" Ta "Command alias if listing commands"
 .It Li "command_list_name" Ta "" Ta "Command name if listing commands"
 .It Li "command_list_usage" Ta "" Ta "Command usage if listing commands"
+.It Li "copy_cursor_line" Ta "" Ta "Line the cursor is on in copy mode"
+.It Li "copy_cursor_word" Ta "" Ta "Word under cursor in copy mode"
 .It Li "copy_cursor_x" Ta "" Ta "Cursor X position in copy mode"
 .It Li "copy_cursor_y" Ta "" Ta "Cursor Y position in copy mode"
 .It Li "cursor_character" Ta "" Ta "Character at cursor in pane"

tmux.h

@@ -1787,6 +1787,8 @@ void		 format_defaults_pane(struct format_tree *,
 void		 format_defaults_paste_buffer(struct format_tree *,
 		     struct paste_buffer *);
 void		 format_lost_client(struct client *);
+char		*format_grid_word(struct grid *, u_int, u_int);
+char		*format_grid_line(struct grid *, u_int);
 
 /* format-draw.c */
 void		 format_draw(struct screen_write_ctx *,

window-copy.c

@@ -564,6 +564,7 @@ static void
 window_copy_formats(struct window_mode_entry *wme, struct format_tree *ft)
 {
 	struct window_copy_mode_data	*data = wme->data;
+	char				*s;
 
 	format_add(ft, "scroll_position", "%d", data->oy);
 	format_add(ft, "rectangle_toggle", "%d", data->rectflag);
@@ -578,6 +579,18 @@ window_copy_formats(struct window_mode_entry *wme, struct format_tree *ft)
 		format_add(ft, "selection_end_x", "%d", data->endselx);
 		format_add(ft, "selection_end_y", "%d", data->endsely);
 	}
+
+	s = format_grid_word(data->screen.grid, data->cx, data->cy);
+	if (s != NULL) {
+		format_add(ft, "copy_cursor_word", "%s", s);
+		free(s);
+	}
+
+	s = format_grid_line(data->screen.grid, data->cy);
+	if (s != NULL) {
+		format_add(ft, "copy_cursor_line", "%s", s);
+		free(s);
+	}
 }
 
 static void