cosmopolitan/libc/alg/replacestr.c

65 lines
3.0 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/alg/alg.h"
#include "libc/alg/arraylist2.h"
#include "libc/bits/safemacros.h"
#include "libc/str/str.h"
#include "libc/sysv/errfuns.h"
/**
* Replaces all instances of NEEDLE in S with REPLACEMENT.
*
* @param needle can't be empty
* @return newly allocated memory that must be free()'d or NULL w/ errno
* @error ENOMEM, EINVAL
*/
char *(replacestr)(const char *s, const char *needle, const char *replacement) {
char *p1, *p2, *res_p;
size_t left, nlen, rlen, res_i, res_n;
if (*needle) {
p1 = s;
left = strlen(s);
nlen = strlen(needle);
rlen = strlen(replacement);
res_i = 0;
res_n = max(left, 32);
if ((res_p = malloc(res_n * sizeof(char)))) {
do {
if (!(p2 = memmem(p1, left, needle, nlen))) break;
if (CONCAT(&res_p, &res_i, &res_n, p1, p2 - p1) == -1 ||
CONCAT(&res_p, &res_i, &res_n, replacement, rlen) == -1) {
goto oom;
}
p2 += nlen;
left -= p2 - p1;
p1 = p2;
} while (left);
if (CONCAT(&res_p, &res_i, &res_n, p1, left + 1) != -1) {
return res_p;
}
}
oom:
free(res_p);
} else {
einval();
}
return NULL;
}