[gtksourceview/wip/chergert/vim: 308/363] add simple completion for command bar

[Christian Hergert <chergert src gnome org>]

commit 3c07f606bf5e02f3b15848b4a33933e53e2f67b4
Author: Christian Hergert <chergert redhat com>
Date:   Fri Nov 5 09:02:30 2021 -0700

    add simple completion for command bar

 gtksourceview/vim/gtk-source-vim-command-bar.c | 35 +++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)
---
diff --git a/gtksourceview/vim/gtk-source-vim-command-bar.c b/gtksourceview/vim/gtk-source-vim-command-bar.c
index 3d7ccb8b..bd7020c4 100644
--- a/gtksourceview/vim/gtk-source-vim-command-bar.c
+++ b/gtksourceview/vim/gtk-source-vim-command-bar.c
@@ -96,6 +96,34 @@ move_history (GtkSourceVimCommandBar *self,
        g_string_append (self->buffer, g_ptr_array_index (history, self->history_pos));
 }
 
+static void
+complete_command (GtkSourceVimCommandBar *self,
+                  const char             *prefix)
+{
+       static const char *commands[] = {
+               ":colorscheme",
+               ":write",
+               ":quit",
+               ":edit",
+               ":open",
+               ":file",
+               ":set",
+       };
+
+       g_assert (GTK_SOURCE_IS_VIM_COMMAND_BAR (self));
+
+       for (guint i = 0; i < G_N_ELEMENTS (commands); i++)
+       {
+               if (g_str_has_prefix (commands[i], prefix))
+               {
+                       g_string_truncate (self->buffer, 0);
+                       g_string_append (self->buffer, commands[i]);
+                       g_string_append_c (self->buffer, ' ');
+                       break;
+               }
+       }
+}
+
 static void
 do_execute (GtkSourceVimCommandBar *self,
             const char             *command)
@@ -152,17 +180,18 @@ gtk_source_vim_command_bar_handle_keypress (GtkSourceVimState *state,
 
                case GDK_KEY_Tab:
                case GDK_KEY_KP_Tab:
-                       break;
+                       complete_command (self, self->buffer->str);
+                       return TRUE;
 
                case GDK_KEY_Up:
                case GDK_KEY_KP_Up:
                        move_history (self, -1);
-                       break;
+                       return TRUE;
 
                case GDK_KEY_Down:
                case GDK_KEY_KP_Down:
                        move_history (self, 1);
-                       break;
+                       return TRUE;
 
                case GDK_KEY_Return:
                case GDK_KEY_KP_Enter: