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Add string similarity function

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Justine Tunney 2024-08-17 16:45:07 -07:00
parent 60e697f7b2
commit 863c704684
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GPG key ID: BE714B4575D6E328
3 changed files with 53 additions and 2 deletions
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5
libc/mem/alg.h
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@ -7,7 +7,6 @@ void *bsearch(const void *, const void *, size_t, size_t,
void *bsearch_r(const void *, const void *, size_t, size_t,
int (*)(const void *, const void *, void *), void *)
paramsnonnull((1, 2, 5)) nosideeffect;
void djbsort(int32_t *, size_t) libcesque;
void qsort3(void *, size_t, size_t,
int (*)(const void *, const void *)) libcesque paramsnonnull();
void qsort(void *, size_t, size_t,
@ -25,8 +24,12 @@ int mergesort(void *, size_t, size_t, int (*)(const void *, const void *));
int mergesort_r(void *, size_t, size_t,
int (*)(const void *, const void *, void *), void *);
#ifdef _COSMO_SOURCE
void djbsort(int32_t *, size_t) libcesque;
int radix_sort_int32(int32_t *, size_t) libcesque;
int radix_sort_int64(int64_t *, size_t) libcesque;
double levenshtein(const char *, const char *) libcesque;
#endif
COSMOPOLITAN_C_END_
#endif /* COSMOPOLITAN_LIBC_ALG_ALG_H_ */

48
libc/mem/levenshtein.c Normal file
View file

@ -0,0 +1,48 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2024 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/mem/alg.h"
#include "libc/mem/mem.h"
#define MIN3(a, b, c) \
((a) < (b) ? ((a) < (c) ? (a) : (c)) : ((b) < (c) ? (b) : (c)))
/**
* Computes similarity between two strings.
*/
double levenshtein(const char *s0, const char *s1) {
int n0 = strlen(s0) + 1;
int n1 = strlen(s1) + 1;
int *col = (int *)malloc(n1 * sizeof(int));
int *pol = (int *)malloc(n1 * sizeof(int));
for (int i = 0; i < n1; i++)
pol[i] = i;
for (int i = 0; i < n0; i++) {
col[0] = i;
for (int j = 1; j < n1; j++)
col[j] = MIN3(1 + col[j - 1], 1 + pol[j],
pol[j - 1] + !(i > 0 && s0[i - 1] == s1[j - 1]));
int *t = col;
col = pol;
pol = t;
}
int dist = pol[n1 - 1];
free(pol);
free(col);
return 1 - dist / ((n0 > n1 ? n0 : n1) - 1.);
}

2
third_party/dlmalloc/locks.inc vendored
View file

@ -34,7 +34,7 @@
#define MLOCK_T atomic_uint
static int malloc_wipe(MLOCK_T *lk) {
bzero(lk, sizeof(*lk));
atomic_store_explicit(lk, 0, memory_order_relaxed);
return 0;
}