cosmopolitan/libc/str/strsep.c

49 lines
2.8 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 │
│ │
│ 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/str/str.h"
/**
* Tokenizes string.
*
* This works by mutating the caller's pointer and the string itself.
* The returned value is the next available token, or NULL if we've
* reached the end. Upon each call, *str is updated to point past the
* terminator we inserted. Multiple delimiter bytes may be passed, which
* are treated as a set of characters, not a substring.
*
* @param str on first call points to var holding string to be tokenized
* and is used by this function to track state on subsequent calls
* @param delim is a set of characters that constitute separators
* @return next token or NULL when we've reached the end or *str==NULL
* @note unlike strtok() this does empty tokens and is re-entrant
*/
char *strsep(char **str, const char *delim) {
char *token = *str;
if (token) {
size_t i = strcspn(token, delim);
char *next = NULL;
if (token[i]) {
token[i] = '\0';
next = &token[i + 1];
}
*str = next;
}
return token;
}