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Diffstat (limited to 'ccan/ccan/htable/htable.h')
-rw-r--r-- | ccan/ccan/htable/htable.h | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/ccan/ccan/htable/htable.h b/ccan/ccan/htable/htable.h new file mode 100644 index 0000000..faaf541 --- /dev/null +++ b/ccan/ccan/htable/htable.h @@ -0,0 +1,290 @@ +/* Licensed under LGPLv2+ - see LICENSE file for details */ +#ifndef CCAN_HTABLE_H +#define CCAN_HTABLE_H +#include "config.h" +#include <ccan/str/str.h> +#include <stdint.h> +#include <stdbool.h> +#include <stdlib.h> + +/* Define CCAN_HTABLE_DEBUG for expensive debugging checks on each call. */ +#define HTABLE_LOC __FILE__ ":" stringify(__LINE__) +#ifdef CCAN_HTABLE_DEBUG +#define htable_debug(h, loc) htable_check((h), loc) +#else +#define htable_debug(h, loc) ((void)loc, h) +#endif + +/** + * struct htable - private definition of a htable. + * + * It's exposed here so you can put it in your structures and so we can + * supply inline functions. + */ +struct htable { + size_t (*rehash)(const void *elem, void *priv); + void *priv; + unsigned int bits, perfect_bitnum; + size_t elems, deleted; + /* These are the bits which are the same in all pointers. */ + uintptr_t common_mask, common_bits; + uintptr_t *table; +}; + +/** + * HTABLE_INITIALIZER - static initialization for a hash table. + * @name: name of this htable. + * @rehash: hash function to use for rehashing. + * @priv: private argument to @rehash function. + * + * This is useful for setting up static and global hash tables. + * + * Example: + * // For simplicity's sake, say hash value is contents of elem. + * static size_t rehash(const void *elem, void *unused) + * { + * (void)unused; + * return *(size_t *)elem; + * } + * static struct htable ht = HTABLE_INITIALIZER(ht, rehash, NULL); + */ +#define HTABLE_INITIALIZER(name, rehash, priv) \ + { rehash, priv, 0, 0, 0, 0, -1, 0, &name.common_bits } + +/** + * htable_init - initialize an empty hash table. + * @ht: the hash table to initialize + * @rehash: hash function to use for rehashing. + * @priv: private argument to @rehash function. + */ +void htable_init(struct htable *ht, + size_t (*rehash)(const void *elem, void *priv), void *priv); + +/** + * htable_init_sized - initialize an empty hash table of given size. + * @ht: the hash table to initialize + * @rehash: hash function to use for rehashing. + * @priv: private argument to @rehash function. + * @size: the number of element. + * + * If this returns false, @ht is still usable, but may need to do reallocation + * upon an add. If this returns true, it will not need to reallocate within + * @size htable_adds. + */ +bool htable_init_sized(struct htable *ht, + size_t (*rehash)(const void *elem, void *priv), + void *priv, size_t size); + +/** + * htable_count - count number of entries in a hash table. + * @ht: the hash table + */ +static inline size_t htable_count(const struct htable *ht) +{ + return ht->elems; +} + +/** + * htable_clear - empty a hash table. + * @ht: the hash table to clear + * + * This doesn't do anything to any pointers left in it. + */ +void htable_clear(struct htable *ht); + + +/** + * htable_check - check hash table for consistency + * @ht: the htable + * @abortstr: the location to print on aborting, or NULL. + * + * Because hash tables have redundant information, consistency checking that + * each element is in the correct location can be done. This is useful as a + * debugging check. If @abortstr is non-NULL, that will be printed in a + * diagnostic if the htable is inconsistent, and the function will abort. + * + * Returns the htable if it is consistent, NULL if not (it can never return + * NULL if @abortstr is set). + */ +struct htable *htable_check(const struct htable *ht, const char *abortstr); + +/** + * htable_copy - duplicate a hash table. + * @dst: the hash table to overwrite + * @src: the hash table to copy + * + * Only fails on out-of-memory. + * + * Equivalent to (but faster than): + * if (!htable_init_sized(dst, src->rehash, src->priv, 1U << src->bits)) + * return false; + * v = htable_first(src, &i); + * while (v) { + * htable_add(dst, v); + * v = htable_next(src, i); + * } + * return true; + */ +#define htable_copy(dst, src) htable_copy_(dst, htable_debug(src, HTABLE_LOC)) +bool htable_copy_(struct htable *dst, const struct htable *src); + +/** + * htable_add - add a pointer into a hash table. + * @ht: the htable + * @hash: the hash value of the object + * @p: the non-NULL pointer (also cannot be (void *)1). + * + * Also note that this can only fail due to allocation failure. Otherwise, it + * returns true. + */ +#define htable_add(ht, hash, p) \ + htable_add_(htable_debug(ht, HTABLE_LOC), hash, p) +bool htable_add_(struct htable *ht, size_t hash, const void *p); + +/** + * htable_del - remove a pointer from a hash table + * @ht: the htable + * @hash: the hash value of the object + * @p: the pointer + * + * Returns true if the pointer was found (and deleted). + */ +#define htable_del(ht, hash, p) \ + htable_del_(htable_debug(ht, HTABLE_LOC), hash, p) +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() + */ +#define htable_firstval(htable, i, hash) \ + htable_firstval_(htable_debug(htable, HTABLE_LOC), i, hash) + +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. + */ +#define htable_nextval(htable, i, hash) \ + htable_nextval_(htable_debug(htable, HTABLE_LOC), i, hash) +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. + */ +#define htable_first(htable, i) \ + htable_first_(htable_debug(htable, HTABLE_LOC), i) +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. + */ +#define htable_next(htable, i) \ + htable_next_(htable_debug(htable, HTABLE_LOC), i) +void *htable_next_(const struct htable *htable, struct htable_iter *i); + +/** + * htable_prev - find the previous entry in the hash table + * @ht: the hashtable + * @i: the struct htable_iter to use + * + * Get previous entry in the hashtable; NULL if all done. + * + * "previous" here only means the item that would have been returned by + * htable_next() before the item it returned most recently. + * + * This is usually used in the middle of (or after) a htable_next iteration and + * to "unwind" actions taken. + */ +#define htable_prev(htable, i) \ + htable_prev_(htable_debug(htable, HTABLE_LOC), i) +void *htable_prev_(const struct htable *htable, struct htable_iter *i); + +/** + * htable_delval - remove an iterated pointer from a hash table + * @ht: the htable + * @i: the htable_iter + * + * Usually used to delete a hash entry after it has been found with + * htable_firstval etc. + */ +#define htable_delval(htable, i) \ + htable_delval_(htable_debug(htable, HTABLE_LOC), i) +void htable_delval_(struct htable *ht, struct htable_iter *i); + +/** + * htable_pick - set iterator to a random valid entry. + * @ht: the htable + * @seed: a random number to use. + * @i: the htable_iter which is output (or NULL). + * + * Usually used with htable_delval to delete a random entry. Returns + * NULL iff the table is empty, otherwise a random entry. + */ +#define htable_pick(htable, seed, i) \ + htable_pick_(htable_debug(htable, HTABLE_LOC), seed, i) +void *htable_pick_(const struct htable *ht, size_t seed, struct htable_iter *i); + +/** + * htable_set_allocator - set calloc/free functions. + * @alloc: allocator to use, must zero memory! + * @free: unallocator to use (@p is NULL or a return from @alloc) + */ +void htable_set_allocator(void *(*alloc)(struct htable *, size_t len), + void (*free)(struct htable *, void *p)); +#endif /* CCAN_HTABLE_H */ |