/*-*- 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"

/**
 * Extracts non-empty tokens from string.
 *
 * @param s is mutated and should be NULL on subsequent calls
 * @param sep is a NUL-terminated set of bytes to consider separators
 * @param state tracks progress between calls
 * @return pointer to next token or NULL for end
 * @see strsep() which is similar
 * @asyncsignalsafe
 */
char *strtok_r(char *s, const char *sep, char **state) {
  size_t leadingseps, tokenlen;
  if (!s) {
    s = *state;
    if (!s) {
      return NULL;
    }
  }
  leadingseps = strspn(s, sep);
  s += leadingseps;
  if (*s) {
    tokenlen = strcspn(s, sep);
    if (s[tokenlen]) {
      s[tokenlen] = '\0';
      *state = &s[tokenlen + 1];
      return s;
    } else if (tokenlen) {
      s[tokenlen] = '\0';
      *state = NULL;
      return s;
    }
  }
  return (*state = NULL);
}