vis-lua: introduce pre-save hook

The first argument is the file object while the second argument denotes
the full path to which it will be written. Path might be `nil` if the
file is going to be written to stdout.

The Lua function is expected to return a boolean value indicating whether
the write operation should proceed or be aborted.

1 files changed, 1 insertions, 0 deletions

diff --git a/vis-lua.h b/vis-lua.h
index 7dab14e..71e30fc 100644
--- a/vis-lua.h
+++ b/vis-lua.h
@@ -23,6 +23,7 @@ void vis_lua_init(Vis*);
 void vis_lua_start(Vis*);
 void vis_lua_quit(Vis*);
 void vis_lua_file_open(Vis*, File*);
+bool vis_lua_file_save_pre(Vis*, File*, const char *path);
 void vis_lua_file_save_post(Vis*, File*, const char *path);
 void vis_lua_file_close(Vis*, File*);
 void vis_lua_win_open(Vis*, Win*);