lib/libc/string/strspn.c

   1 /*-
   2  * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Andreas Hauser <andy-dragonfly@splashground.de>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/lib/libc/string/strspn.c,v 1.5 2008/05/15 03:48:58 dillon Exp $
  35  */
  36
  37 #include <assert.h>
  38 #include <limits.h>
  39 #include <stdbool.h>
  40 #include <string.h>
  41
  42 /*
  43  * Longest initial segment of string *str, containing any chars from *chars.
  44  */
  45 size_t
  46 strspn(const char *str, const char *chars)
  47 {
  48         const char *s;
  49         bool charset[UCHAR_MAX + 1];
  50
  51          _DIAGASSERT(str != NULL);
  52          _DIAGASSERT(chars != NULL);
  53
  54         if(*str == '\0')
  55                 return 0;
  56         if(*chars == '\0')
  57                 return strlen(str);
  58
  59         memset(charset, false, sizeof(charset));
  60         for( ; *chars != '\0'; chars++)
  61                 charset[*(const unsigned char *)chars] = true;
  62
  63         for(s = str; charset[*(const unsigned char *)s] == true; s++)
  64                 /* NOTHING */
  65                 ;
  66
  67         return (s - str);
  68 }