m_config: support flatten and merge flags for suboptions

M_OPT_PREFIXED allows adding top-level options with the suboption
mechanism. The point of this is that, even though these options are
top-level options, they don't need to be added directly to a top-
level option array (such as mplayer_opts[]). Instead, the suboption
can be defined in a separate source file. Only a suboption declaration
is needed to add these options.

M_OPT_MERGE is similar to M_OPT_PREFIXED, but doesn't add the name of
the suboptions entry as prefix.

Given you have a suboption declaration "prefix" and the suboption
"subopt", you can pass them as follows on the command line:
  normal:           --prefix=subopt=value
  M_OPT_PREFIXED:   --prefix-subopt=value
  M_OPT_MERGE:      --subopt=value

1 files changed, 8 insertions, 0 deletions

diff --git a/m_option.h b/m_option.h
index 4ab7e9c1d2..e0321d1de1 100644
--- a/m_option.h
+++ b/m_option.h
@@ -290,6 +290,14 @@ struct m_option {
 // For m_option_type_choice, the first listed choice will be used.
 #define M_OPT_IMPLICIT_DEFAULT  (1 << 7)
 
+// For options with children, add all children as top-level arguments
+// (e.g. "--parent=child=value" becomes "--parent-child=value")
+#define M_OPT_PREFIXED          (1 << 8)
+
+// Similar to M_OPT_PREFIXED, but drop the prefix.
+// (e.g. "--parent=child=value" becomes "--child=value")
+#define M_OPT_MERGE             (1 << 9)
+
 // These are kept for compatibility with older code.
 #define CONF_MIN                M_OPT_MIN
 #define CONF_MAX                M_OPT_MAX