m_config: support auto-allocated sub-structs

Given your option struct has a field that is a pointer to another
struct, this commit allows you to declare options that write into that
other struct. The code in m_config will dereference the pointer field
on its own if such an option is accessed. If the field is NULL on
initialization of the containing m_config, the struct is automatically
allocated.

OPT_SUBSTRUCT() can be used to declare such a field.
struct m_sub_options is used to describe the pointed-to struct, and
includes size and defaults if the struct has to be allocated by
m_config.

1 files changed, 6 insertions, 0 deletions

diff --git a/m_option.c b/m_option.c
index 35b5efc98d..22abee1496 100644
--- a/m_option.c
+++ b/m_option.c
@@ -907,6 +907,12 @@ const m_option_type_t m_option_type_subconfig = {
     .parse = parse_subconf,
 };
 
+const m_option_type_t m_option_type_subconfig_struct = {
+    .name = "Subconfig",
+    .flags = M_OPT_TYPE_HAS_CHILD | M_OPT_TYPE_USE_SUBSTRUCT,
+    .parse = parse_subconf,
+};
+
 #include "libmpcodecs/img_format.h"
 
 /* FIXME: snyc with img_format.h */