notmuch-dump: add --format=(batch-tag|sup)

sup is the old format, and remains the default, at least until
restore is converted to parse this format.

Each line of the batch-tag format is modelled on the syntax of notmuch tag:
- "notmuch tag" is omitted from the front of the line
- The dump format only uses query strings of a single message-id.
- Each space seperated tag/message-id is 'hex-encoded' to remove
  trouble-making characters.
- It is permitted (and will be useful) for there to be no tags before
  the query.

In particular this format won't have the same problem with e.g. spaces
in message-ids or tags; they will be round-trip-able.

1 files changed, 13 insertions, 0 deletions

diff --git a/dump-restore-private.h b/dump-restore-private.h
new file mode 100644
index 00000000..896a0043
--- /dev/null
+++ b/dump-restore-private.h
@@ -0,0 +1,13 @@
+#ifndef DUMP_RESTORE_PRIVATE_H
+#define DUMP_RESTORE_PRIVATE_H
+
+#include "hex-escape.h"
+#include "command-line-arguments.h"
+
+typedef enum dump_formats {
+    DUMP_FORMAT_AUTO,
+    DUMP_FORMAT_BATCH_TAG,
+    DUMP_FORMAT_SUP
+} dump_format_t;
+
+#endif