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git/khash.h
Karsten Blees 039dc71a7c hashmap: factor out getting a hash code from a SHA1 
Copying the first bytes of a SHA1 is duplicated in six places,
however, the implications (the actual value would depend on the
endianness of the platform) is documented only once.

Add a properly documented API for this.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-07 13:56:24 -07:00

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/* The MIT License
Copyright (c) 2008, 2009, 2011 by Attractive Chaos <attractor@live.co.uk>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#ifndef __AC_KHASH_H
#define __AC_KHASH_H
#define AC_VERSION_KHASH_H "0.2.8"
typedef uint32_t khint32_t;
typedef uint64_t khint64_t;
typedef khint32_t khint_t;
typedef khint_t khiter_t;
#define __ac_isempty(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&2)
#define __ac_isdel(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&1)
#define __ac_iseither(flag, i) ((flag[i>>4]>>((i&0xfU)<<1))&3)
#define __ac_set_isdel_false(flag, i) (flag[i>>4]&=~(1ul<<((i&0xfU)<<1)))
#define __ac_set_isempty_false(flag, i) (flag[i>>4]&=~(2ul<<((i&0xfU)<<1)))
#define __ac_set_isboth_false(flag, i) (flag[i>>4]&=~(3ul<<((i&0xfU)<<1)))
#define __ac_set_isdel_true(flag, i) (flag[i>>4]|=1ul<<((i&0xfU)<<1))
#define __ac_fsize(m) ((m) < 16? 1 : (m)>>4)
#define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))
static inline khint_t __ac_X31_hash_string(const char *s)
{
khint_t h = (khint_t)*s;
if (h) for (++s ; *s; ++s) h = (h << 5) - h + (khint_t)*s;
return h;
}
#define kh_str_hash_func(key) __ac_X31_hash_string(key)
#define kh_str_hash_equal(a, b) (strcmp(a, b) == 0)
static const double __ac_HASH_UPPER = 0.77;
#define __KHASH_TYPE(name, khkey_t, khval_t) \
typedef struct { \
khint_t n_buckets, size, n_occupied, upper_bound; \
khint32_t *flags; \
khkey_t *keys; \
khval_t *vals; \
} kh_##name##_t;
#define __KHASH_PROTOTYPES(name, khkey_t, khval_t) \
extern kh_##name##_t *kh_init_##name(void); \
extern void kh_destroy_##name(kh_##name##_t *h); \
extern void kh_clear_##name(kh_##name##_t *h); \
extern khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key); \
extern int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets); \
extern khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret); \
extern void kh_del_##name(kh_##name##_t *h, khint_t x);
#define __KHASH_IMPL(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
SCOPE kh_##name##_t *kh_init_##name(void) { \
return (kh_##name##_t*)xcalloc(1, sizeof(kh_##name##_t)); \
} \
SCOPE void kh_destroy_##name(kh_##name##_t *h) \
{ \
if (h) { \
free((void *)h->keys); free(h->flags); \
free((void *)h->vals); \
free(h); \
} \
} \
SCOPE void kh_clear_##name(kh_##name##_t *h) \
{ \
if (h && h->flags) { \
memset(h->flags, 0xaa, __ac_fsize(h->n_buckets) * sizeof(khint32_t)); \
h->size = h->n_occupied = 0; \
} \
} \
SCOPE khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key) \
{ \
if (h->n_buckets) { \
khint_t k, i, last, mask, step = 0; \
mask = h->n_buckets - 1; \
k = __hash_func(key); i = k & mask; \
last = i; \
while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
i = (i + (++step)) & mask; \
if (i == last) return h->n_buckets; \
} \
return __ac_iseither(h->flags, i)? h->n_buckets : i; \
} else return 0; \
} \
SCOPE int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets) \
{ /* This function uses 0.25*n_buckets bytes of working space instead of [sizeof(key_t+val_t)+.25]*n_buckets. */ \
khint32_t *new_flags = NULL; \
khint_t j = 1; \
{ \
kroundup32(new_n_buckets); \
if (new_n_buckets < 4) new_n_buckets = 4; \
if (h->size >= (khint_t)(new_n_buckets * __ac_HASH_UPPER + 0.5)) j = 0; /* requested size is too small */ \
else { /* hash table size to be changed (shrink or expand); rehash */ \
new_flags = (khint32_t*)xmalloc(__ac_fsize(new_n_buckets) * sizeof(khint32_t)); \
if (!new_flags) return -1; \
memset(new_flags, 0xaa, __ac_fsize(new_n_buckets) * sizeof(khint32_t)); \
if (h->n_buckets < new_n_buckets) { /* expand */ \
khkey_t *new_keys = (khkey_t*)xrealloc((void *)h->keys, new_n_buckets * sizeof(khkey_t)); \
if (!new_keys) return -1; \
h->keys = new_keys; \
if (kh_is_map) { \
khval_t *new_vals = (khval_t*)xrealloc((void *)h->vals, new_n_buckets * sizeof(khval_t)); \
if (!new_vals) return -1; \
h->vals = new_vals; \
} \
} /* otherwise shrink */ \
} \
} \
if (j) { /* rehashing is needed */ \
for (j = 0; j != h->n_buckets; ++j) { \
if (__ac_iseither(h->flags, j) == 0) { \
khkey_t key = h->keys[j]; \
khval_t val; \
khint_t new_mask; \
new_mask = new_n_buckets - 1; \
if (kh_is_map) val = h->vals[j]; \
__ac_set_isdel_true(h->flags, j); \
while (1) { /* kick-out process; sort of like in Cuckoo hashing */ \
khint_t k, i, step = 0; \
k = __hash_func(key); \
i = k & new_mask; \
while (!__ac_isempty(new_flags, i)) i = (i + (++step)) & new_mask; \
__ac_set_isempty_false(new_flags, i); \
if (i < h->n_buckets && __ac_iseither(h->flags, i) == 0) { /* kick out the existing element */ \
{ khkey_t tmp = h->keys[i]; h->keys[i] = key; key = tmp; } \
if (kh_is_map) { khval_t tmp = h->vals[i]; h->vals[i] = val; val = tmp; } \
__ac_set_isdel_true(h->flags, i); /* mark it as deleted in the old hash table */ \
} else { /* write the element and jump out of the loop */ \
h->keys[i] = key; \
if (kh_is_map) h->vals[i] = val; \
break; \
} \
} \
} \
} \
if (h->n_buckets > new_n_buckets) { /* shrink the hash table */ \
h->keys = (khkey_t*)xrealloc((void *)h->keys, new_n_buckets * sizeof(khkey_t)); \
if (kh_is_map) h->vals = (khval_t*)xrealloc((void *)h->vals, new_n_buckets * sizeof(khval_t)); \
} \
free(h->flags); /* free the working space */ \
h->flags = new_flags; \
h->n_buckets = new_n_buckets; \
h->n_occupied = h->size; \
h->upper_bound = (khint_t)(h->n_buckets * __ac_HASH_UPPER + 0.5); \
} \
return 0; \
} \
SCOPE khint_t kh_put_##name(kh_##name##_t *h, khkey_t key, int *ret) \
{ \
khint_t x; \
if (h->n_occupied >= h->upper_bound) { /* update the hash table */ \
if (h->n_buckets > (h->size<<1)) { \
if (kh_resize_##name(h, h->n_buckets - 1) < 0) { /* clear "deleted" elements */ \
*ret = -1; return h->n_buckets; \
} \
} else if (kh_resize_##name(h, h->n_buckets + 1) < 0) { /* expand the hash table */ \
*ret = -1; return h->n_buckets; \
} \
} /* TODO: to implement automatically shrinking; resize() already support shrinking */ \
{ \
khint_t k, i, site, last, mask = h->n_buckets - 1, step = 0; \
x = site = h->n_buckets; k = __hash_func(key); i = k & mask; \
if (__ac_isempty(h->flags, i)) x = i; /* for speed up */ \
else { \
last = i; \
while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
if (__ac_isdel(h->flags, i)) site = i; \
i = (i + (++step)) & mask; \
if (i == last) { x = site; break; } \
} \
if (x == h->n_buckets) { \
if (__ac_isempty(h->flags, i) && site != h->n_buckets) x = site; \
else x = i; \
} \
} \
} \
if (__ac_isempty(h->flags, x)) { /* not present at all */ \
h->keys[x] = key; \
__ac_set_isboth_false(h->flags, x); \
++h->size; ++h->n_occupied; \
*ret = 1; \
} else if (__ac_isdel(h->flags, x)) { /* deleted */ \
h->keys[x] = key; \
__ac_set_isboth_false(h->flags, x); \
++h->size; \
*ret = 2; \
} else *ret = 0; /* Don't touch h->keys[x] if present and not deleted */ \
return x; \
} \
SCOPE void kh_del_##name(kh_##name##_t *h, khint_t x) \
{ \
if (x != h->n_buckets && !__ac_iseither(h->flags, x)) { \
__ac_set_isdel_true(h->flags, x); \
--h->size; \
} \
}
#define KHASH_DECLARE(name, khkey_t, khval_t) \
__KHASH_TYPE(name, khkey_t, khval_t) \
__KHASH_PROTOTYPES(name, khkey_t, khval_t)
#define KHASH_INIT2(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
__KHASH_TYPE(name, khkey_t, khval_t) \
__KHASH_IMPL(name, SCOPE, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal)
#define KHASH_INIT(name, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal) \
KHASH_INIT2(name, static inline, khkey_t, khval_t, kh_is_map, __hash_func, __hash_equal)
/* Other convenient macros... */
/*! @function
@abstract Test whether a bucket contains data.
@param h Pointer to the hash table [khash_t(name)*]
@param x Iterator to the bucket [khint_t]
@return 1 if containing data; 0 otherwise [int]
*/
#define kh_exist(h, x) (!__ac_iseither((h)->flags, (x)))
/*! @function
@abstract Get key given an iterator
@param h Pointer to the hash table [khash_t(name)*]
@param x Iterator to the bucket [khint_t]
@return Key [type of keys]
*/
#define kh_key(h, x) ((h)->keys[x])
/*! @function
@abstract Get value given an iterator
@param h Pointer to the hash table [khash_t(name)*]
@param x Iterator to the bucket [khint_t]
@return Value [type of values]
@discussion For hash sets, calling this results in segfault.
*/
#define kh_val(h, x) ((h)->vals[x])
/*! @function
@abstract Alias of kh_val()
*/
#define kh_value(h, x) ((h)->vals[x])
/*! @function
@abstract Get the start iterator
@param h Pointer to the hash table [khash_t(name)*]
@return The start iterator [khint_t]
*/
#define kh_begin(h) (khint_t)(0)
/*! @function
@abstract Get the end iterator
@param h Pointer to the hash table [khash_t(name)*]
@return The end iterator [khint_t]
*/
#define kh_end(h) ((h)->n_buckets)
/*! @function
@abstract Get the number of elements in the hash table
@param h Pointer to the hash table [khash_t(name)*]
@return Number of elements in the hash table [khint_t]
*/
#define kh_size(h) ((h)->size)
/*! @function
@abstract Get the number of buckets in the hash table
@param h Pointer to the hash table [khash_t(name)*]
@return Number of buckets in the hash table [khint_t]
*/
#define kh_n_buckets(h) ((h)->n_buckets)
/*! @function
@abstract Iterate over the entries in the hash table
@param h Pointer to the hash table [khash_t(name)*]
@param kvar Variable to which key will be assigned
@param vvar Variable to which value will be assigned
@param code Block of code to execute
*/
#define kh_foreach(h, kvar, vvar, code) { khint_t __i; \
for (__i = kh_begin(h); __i != kh_end(h); ++__i) { \
if (!kh_exist(h,__i)) continue; \
(kvar) = kh_key(h,__i); \
(vvar) = kh_val(h,__i); \
code; \
} }
/*! @function
@abstract Iterate over the values in the hash table
@param h Pointer to the hash table [khash_t(name)*]
@param vvar Variable to which value will be assigned
@param code Block of code to execute
*/
#define kh_foreach_value(h, vvar, code) { khint_t __i; \
for (__i = kh_begin(h); __i != kh_end(h); ++__i) { \
if (!kh_exist(h,__i)) continue; \
(vvar) = kh_val(h,__i); \
code; \
} }
#define __kh_oid_cmp(a, b) (hashcmp(a, b) == 0)
KHASH_INIT(sha1, const unsigned char *, void *, 1, sha1hash, __kh_oid_cmp)
typedef kh_sha1_t khash_sha1;
KHASH_INIT(sha1_pos, const unsigned char *, int, 1, sha1hash, __kh_oid_cmp)
typedef kh_sha1_pos_t khash_sha1_pos;
#endif /* __AC_KHASH_H */
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