xref: /dflybsd-src/lib/libc/string/strspn.c (revision 86d7f5d305c6adaa56ff4582ece9859d73106103)

/*-
 * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Andreas Hauser <andy-dragonfly@splashground.de>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $DragonFly: src/lib/libc/string/strspn.c,v 1.5 2008/05/15 03:48:58 dillon Exp $
 */

#include <assert.h>
#include <limits.h>
#include <stdbool.h>
#include <string.h>

/*
 * Longest initial segment of string *str, containing any chars from *chars.
 */
size_t
strspn(const char *str, const char *chars)
{
        const char *s;
        bool charset[UCHAR_MAX + 1];

         _DIAGASSERT(str != NULL);
         _DIAGASSERT(chars != NULL);

        if(*str == '\0')
                return 0;
        if(*chars == '\0')
                return 0;

        memset(charset, false, sizeof(charset));
        for( ; *chars != '\0'; chars++)
                charset[*(const unsigned char *)chars] = true;

        for(s = str; charset[*(const unsigned char *)s] == true; s++)
                /* NOTHING */
                ;

        return (s - str);
}