htable: add a htable_prev method to oppose _next

[ccan] / ccan / htable / htable_type.h

diff --git a/ccan/htable/htable_type.h b/ccan/htable/htable_type.h
index 61535c2c665c43fa611f5b995205e9fccd94f648..ba33f139d72a89387c73847b80bab73f47e1ce15 100644 (file)
--- a/ccan/htable/htable_type.h
+++ b/ccan/htable/htable_type.h
@@ -43,6 +43,7 @@
  * Iteration over hashtable is also supported:
  *     type *<name>_first(const struct <name> *ht, struct <name>_iter *i);
  *     type *<name>_next(const struct <name> *ht, struct <name>_iter *i);
+ *     type *<name>_prev(const struct <name> *ht, struct <name>_iter *i);
  *
  * It's currently safe to iterate over a changing hashtable, but you might
  * miss an element.  Iteration isn't very efficient, either.
@@ -81,7 +82,7 @@
                return htable_del(&ht->raw, hashfn(keyof(elem)), elem); \
        }                                                               \
        static inline UNNEEDED type *name##_get(const struct name *ht,  \
-                                      const HTABLE_KTYPE(keyof) k)     \
+                                      const HTABLE_KTYPE(keyof, type) k) \
        {                                                               \
                /* Typecheck for eqfn */                                \
                (void)sizeof(eqfn((const type *)NULL,                   \
@@ -92,7 +93,7 @@
                                  k);                                   \
        }                                                               \
        static inline UNNEEDED type *name##_getmatch_(const struct name *ht, \
-                                        const HTABLE_KTYPE(keyof) k,   \
+                                        const HTABLE_KTYPE(keyof, type) k, \
                                         size_t h,                      \
                                         type *v,                       \
                                         struct name##_iter *iter)      \
@@ -105,7 +106,7 @@
                return v;                                               \
        }                                                               \
        static inline UNNEEDED type *name##_getfirst(const struct name *ht, \
-                                        const HTABLE_KTYPE(keyof) k,   \
+                                        const HTABLE_KTYPE(keyof, type) k, \
                                         struct name##_iter *iter)      \
        {                                                               \
                size_t h = hashfn(k);                                   \
@@ -113,7 +114,7 @@
                return name##_getmatch_(ht, k, h, v, iter);                     \
        }                                                               \
        static inline UNNEEDED type *name##_getnext(const struct name *ht, \
-                                        const HTABLE_KTYPE(keyof) k,   \
+                                        const HTABLE_KTYPE(keyof, type) k, \
                                         struct name##_iter *iter)      \
        {                                                               \
                size_t h = hashfn(k);                                   \
@@ -121,7 +122,7 @@
                return name##_getmatch_(ht, k, h, v, iter);             \
        }                                                               \
        static inline UNNEEDED bool name##_delkey(struct name *ht,      \
-                                        const HTABLE_KTYPE(keyof) k)   \
+                                        const HTABLE_KTYPE(keyof, type) k) \
        {                                                               \
                type *elem = name##_get(ht, k);                         \
                if (elem)                                               \
@@ -137,11 +138,16 @@
                                        struct name##_iter *iter)       \
        {                                                               \
                return htable_next(&ht->raw, &iter->i);                 \
+       }                                                               \
+       static inline UNNEEDED type *name##_prev(const struct name *ht, \
+                                       struct name##_iter *iter)       \
+       {                                                               \
+               return htable_prev(&ht->raw, &iter->i);                 \
        }
 
 #if HAVE_TYPEOF
-#define HTABLE_KTYPE(keyof) typeof(keyof(NULL))
+#define HTABLE_KTYPE(keyof, type) typeof(keyof((const type *)NULL))
 #else
-#define HTABLE_KTYPE(keyof) void *
+#define HTABLE_KTYPE(keyof, type) void *
 #endif
 #endif /* CCAN_HTABLE_TYPE_H */