args: keyword extraction mechanism.

Implement a mechanism for extracting keyword arguments out of
"struct args *" argument lists which avoids consing up an
argument list and scanning it multiple times for multiple
keywords.

* args.c (args_for_each): New function.
(struct args_bool_key, struct args_bool_ctx): New struct
types.
(args_key_check_store): New static function.
(args_keys_extract_vl, args_key_extract): New functions.

* args.h (args_for_each, args_keys_extract_vl,
args_key_extract): Declared.

1 files changed, 5 insertions, 0 deletions

diff --git a/args.h b/args.h
index 5877e44c..6e0036c0 100644
--- a/args.h
+++ b/args.h
@@ -186,3 +186,8 @@ struct args *args_copy_zap(struct args *to, struct args *from);
 struct args *args_cat_zap(struct args *to, struct args *from);
 struct args *args_cat_zap_from(struct args *to, struct args *from, cnum index);
 val args_copy_to_list(struct args *args);
+void args_for_each(struct args *args,
+                   int (*fn)(val arg, int ix, mem_t *ctx),
+                   mem_t *ctx);
+void args_keys_extract_vl(struct args *args, va_list);
+void args_keys_extract(struct args *args, ...);