tabpage: track last-used tabpage #11626

In a multi-window scenario, it is possible to return focus to the last
accessed window via n_CTRL-W_p.  However, in the case of a multi-tab
scenario, there was previously no way to return focus to the last
accessed *tab*.  Here, that ability is added via n_g<tab>.

Additionally, the index of the previous tab is exposed via
tabpagenr('#'), mirroring the existing functionality of winnr('#').

1 files changed, 19 insertions, 0 deletions

diff --git a/src/nvim/window.c b/src/nvim/window.c
index 79d7a8acba..4d105dd11e 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -519,6 +519,10 @@ wingotofile:
       do_nv_ident('g', xchar);
       break;
 
+    case TAB:
+      goto_tabpage_lastused();
+      break;
+
     case 'f':                       /* CTRL-W gf: "gf" in a new tab page */
     case 'F':                       /* CTRL-W gF: "gF" in a new tab page */
       cmdmod.tab = tabpage_index(curtab) + 1;
@@ -3691,6 +3695,10 @@ void free_tabpage(tabpage_T *tp)
   hash_init(&tp->tp_vars->dv_hashtab);
   unref_var_dict(tp->tp_vars);
 
+  if (tp == lastused_tabpage) {
+    lastused_tabpage = NULL;
+  }
+
   xfree(tp->tp_localdir);
   xfree(tp);
 }
@@ -3750,6 +3758,8 @@ int win_new_tabpage(int after, char_u *filename)
 
     tabpage_check_windows(tp);
 
+    lastused_tabpage = tp;
+
     apply_autocmds(EVENT_WINNEW, NULL, NULL, false, curbuf);
     apply_autocmds(EVENT_WINENTER, NULL, NULL, false, curbuf);
     apply_autocmds(EVENT_TABNEW, filename, filename, false, curbuf);
@@ -3976,6 +3986,7 @@ static void enter_tabpage(tabpage_T *tp, buf_T *old_curbuf, int trigger_enter_au
   if (curtab->tp_old_Columns != Columns && starting == 0)
     shell_new_columns();        /* update window widths */
 
+  lastused_tabpage = old_curtab;
 
   /* Apply autocommands after updating the display, when 'rows' and
    * 'columns' have been set correctly. */
@@ -4095,6 +4106,14 @@ void goto_tabpage_tp(tabpage_T *tp, int trigger_enter_autocmds, int trigger_leav
   }
 }
 
+// Go to the last accessed tab page, if there is one.
+void goto_tabpage_lastused(void)
+{
+  if (valid_tabpage(lastused_tabpage)) {
+    goto_tabpage_tp(lastused_tabpage, true, true);
+  }
+}
+
 /*
  * Enter window "wp" in tab page "tp".
  * Also updates the GUI tab.