htable: first implementation

[ccan] / ccan / htable / htable.h

diff --git a/ccan/htable/htable.h b/ccan/htable/htable.h
new file mode 100644 (file)
index 0000000..b684429
--- /dev/null
+++ b/ccan/htable/htable.h
@@ -0,0 +1,138 @@
+#ifndef CCAN_HTABLE_H
+#define CCAN_HTABLE_H
+#include "config.h"
+#include <stdbool.h>
+#include <stdlib.h>
+
+struct htable;
+
+/**
+ * htable_new - allocate a hash tree.
+ * @rehash: hash function to use for rehashing.
+ * @priv: private argument to @rehash function.
+ */
+struct htable *htable_new(size_t (*hash)(const void *elem, void *priv),
+                         void *priv);
+
+/**
+ * htable_free - dellocate a hash tree.
+ *
+ * This doesn't do anything to any pointers left in it.
+ */
+void htable_free(const struct htable *);
+
+/**
+ * htable_rehash - use a hashtree's rehash function
+ * @elem: the argument to rehash()
+ *
+ */
+size_t htable_rehash(const void *elem);
+
+/**
+ * htable_add - add a pointer into a hash tree.
+ * @ht: the htable
+ * @hash: the hash value of the object
+ * @p: the non-NULL pointer
+ *
+ * Also note that this can only fail due to allocation failure.  Otherwise, it
+ * returns true.
+ */
+bool htable_add(struct htable *ht, size_t hash, const void *p);
+
+/**
+ * htable_del - remove a pointer from a hash tree
+ * @ht: the htable
+ * @hash: the hash value of the object
+ * @p: the pointer
+ *
+ * Returns true if the pointer was found (and deleted).
+ */
+bool htable_del(struct htable *ht, size_t hash, const void *p);
+
+/**
+ * struct htable_iter - iterator or htable_first or htable_firstval etc.
+ *
+ * This refers to a location inside the hashtable.
+ */
+struct htable_iter {
+       size_t off;
+};
+
+/**
+ * htable_firstval - find a candidate for a given hash value
+ * @htable: the hashtable
+ * @i: the struct htable_iter to initialize
+ * @hash: the hash value
+ *
+ * You'll need to check the value is what you want; returns NULL if none.
+ * See Also:
+ *     htable_delval()
+ */
+void *htable_firstval(const struct htable *htable,
+                     struct htable_iter *i, size_t hash);
+
+/**
+ * htable_nextval - find another candidate for a given hash value
+ * @htable: the hashtable
+ * @i: the struct htable_iter to initialize
+ * @hash: the hash value
+ *
+ * You'll need to check the value is what you want; returns NULL if no more.
+ */
+void *htable_nextval(const struct htable *htable,
+                    struct htable_iter *i, size_t hash);
+
+/**
+ * htable_get - find an entry in the hash table
+ * @ht: the hashtable
+ * @h: the hash value of the entry
+ * @cmp: the comparison function
+ * @ptr: the pointer to hand to the comparison function.
+ *
+ * Convenient inline wrapper for htable_firstval/htable_nextval loop.
+ */
+static inline void *htable_get(const struct htable *ht,
+                              size_t h,
+                              bool (*cmp)(const void *candidate, void *ptr),
+                              const void *ptr)
+{
+       struct htable_iter i;
+       void *c;
+
+       for (c = htable_firstval(ht,&i,h); c; c = htable_nextval(ht,&i,h)) {
+               if (cmp(c, (void *)ptr))
+                       return c;
+       }
+       return NULL;
+}
+
+/**
+ * htable_first - find an entry in the hash table
+ * @ht: the hashtable
+ * @i: the struct htable_iter to initialize
+ *
+ * Get an entry in the hashtable; NULL if empty.
+ */
+void *htable_first(const struct htable *htable, struct htable_iter *i);
+
+/**
+ * htable_next - find another entry in the hash table
+ * @ht: the hashtable
+ * @i: the struct htable_iter to use
+ *
+ * Get another entry in the hashtable; NULL if all done.
+ * This is usually used after htable_first or prior non-NULL htable_next.
+ */
+void *htable_next(const struct htable *htable, struct htable_iter *i);
+
+/**
+ * htable_delval - remove an iterated pointer from a hash tree
+ * @ht: the htable
+ * @i: the htable_iter
+ *
+ * Usually used to delete a hash entry after it has been found with
+ * htable_firstval etc.
+ */
+void htable_delval(struct htable *ht, struct htable_iter *i);
+
+#endif /* CCAN_HTABLE_H */