cosmopolitan/libc/str/strsep.c

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2020-06-15 14:18:57 +00:00
/*-*- 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
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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.
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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.
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*/
#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;
}