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, 4 insertions, 0 deletions

diff --git a/vis.c b/vis.c
index dcd7457..f8d3dbf 100644
--- a/vis.c
+++ b/vis.c
@@ -58,6 +58,7 @@ bool vis_event_emit(Vis *vis, enum VisEvents id, ...) {
 			vis->event->vis_start(vis);
 		break;
 	case VIS_EVENT_FILE_OPEN:
+	case VIS_EVENT_FILE_SAVE_PRE:
 	case VIS_EVENT_FILE_SAVE_POST:
 	case VIS_EVENT_FILE_CLOSE:
 	{
@@ -66,6 +67,9 @@ bool vis_event_emit(Vis *vis, enum VisEvents id, ...) {
 			break;
 		if (id == VIS_EVENT_FILE_OPEN && vis->event->file_open) {
 			vis->event->file_open(vis, file);
+		} else if (id == VIS_EVENT_FILE_SAVE_PRE && vis->event->file_save_pre) {
+			const char *path = va_arg(ap, const char*);
+			ret = vis->event->file_save_pre(vis, file, path);
 		} else if (id == VIS_EVENT_FILE_SAVE_POST && vis->event->file_save_post) {
 			const char *path = va_arg(ap, const char*);
 			vis->event->file_save_post(vis, file, path);