mirror of
https://github.com/git/git
synced 2024-08-24 18:26:02 +00:00
![René Scharfe](/assets/img/avatar_default.png)
Now that all of its callers are gone, remove llist_mergesort(). Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
106 lines
2.9 KiB
C
106 lines
2.9 KiB
C
#ifndef MERGESORT_H
|
|
#define MERGESORT_H
|
|
|
|
/* Combine two sorted lists. Take from `list` on equality. */
|
|
#define DEFINE_LIST_MERGE_INTERNAL(name, type) \
|
|
static type *name##__merge(type *list, type *other, \
|
|
int (*compare_fn)(const type *, const type *))\
|
|
{ \
|
|
type *result = list, *tail; \
|
|
int prefer_list = compare_fn(list, other) <= 0; \
|
|
\
|
|
if (!prefer_list) { \
|
|
result = other; \
|
|
SWAP(list, other); \
|
|
} \
|
|
for (;;) { \
|
|
do { \
|
|
tail = list; \
|
|
list = name##__get_next(list); \
|
|
if (!list) { \
|
|
name##__set_next(tail, other); \
|
|
return result; \
|
|
} \
|
|
} while (compare_fn(list, other) < prefer_list); \
|
|
name##__set_next(tail, other); \
|
|
prefer_list ^= 1; \
|
|
SWAP(list, other); \
|
|
} \
|
|
}
|
|
|
|
/*
|
|
* Perform an iterative mergesort using an array of sublists.
|
|
*
|
|
* n is the number of items.
|
|
* ranks[i] is undefined if n & 2^i == 0, and assumed empty.
|
|
* ranks[i] contains a sublist of length 2^i otherwise.
|
|
*
|
|
* The number of bits in a void pointer limits the number of objects
|
|
* that can be created, and thus the number of array elements necessary
|
|
* to be able to sort any valid list.
|
|
*
|
|
* Adding an item to this array is like incrementing a binary number;
|
|
* positional values for set bits correspond to sublist lengths.
|
|
*/
|
|
#define DEFINE_LIST_SORT_INTERNAL(scope, name, type) \
|
|
scope void name(type **listp, \
|
|
int (*compare_fn)(const type *, const type *)) \
|
|
{ \
|
|
type *list = *listp; \
|
|
type *ranks[bitsizeof(type *)]; \
|
|
size_t n = 0; \
|
|
\
|
|
if (!list) \
|
|
return; \
|
|
\
|
|
for (;;) { \
|
|
int i; \
|
|
size_t m; \
|
|
type *next = name##__get_next(list); \
|
|
if (next) \
|
|
name##__set_next(list, NULL); \
|
|
for (i = 0, m = n;; i++, m >>= 1) { \
|
|
if (m & 1) { \
|
|
list = name##__merge(ranks[i], list, \
|
|
compare_fn); \
|
|
} else if (next) { \
|
|
break; \
|
|
} else if (!m) { \
|
|
*listp = list; \
|
|
return; \
|
|
} \
|
|
} \
|
|
n++; \
|
|
ranks[i] = list; \
|
|
list = next; \
|
|
} \
|
|
}
|
|
|
|
#define DECLARE_LIST_SORT(scope, name, type) \
|
|
scope void name(type **listp, \
|
|
int (*compare_fn)(const type *, const type *))
|
|
|
|
#define DEFINE_LIST_SORT_DEBUG(scope, name, type, next_member, \
|
|
on_get_next, on_set_next) \
|
|
\
|
|
static inline type *name##__get_next(const type *elem) \
|
|
{ \
|
|
on_get_next; \
|
|
return elem->next_member; \
|
|
} \
|
|
\
|
|
static inline void name##__set_next(type *elem, type *next) \
|
|
{ \
|
|
on_set_next; \
|
|
elem->next_member = next; \
|
|
} \
|
|
\
|
|
DEFINE_LIST_MERGE_INTERNAL(name, type) \
|
|
DEFINE_LIST_SORT_INTERNAL(scope, name, type) \
|
|
DECLARE_LIST_SORT(scope, name, type)
|
|
|
|
#define DEFINE_LIST_SORT(scope, name, type, next_member) \
|
|
DEFINE_LIST_SORT_DEBUG(scope, name, type, next_member, (void)0, (void)0)
|
|
|
|
#endif
|