/* Copyright (c) 2016, 2019 Dennis Wölfing
 *
 * 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.
 */

/* libc/src/string/strspn.c
 * Calculates the length of a substring.
 */

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

size_t strspn(const char* string, const char* characters) {
    size_t result = 0;

    while (true) {
        bool found = false;
        for (size_t i = 0; characters[i]; i++) {
            if (string[result] == characters[i]) {
                found = true;
                break;
            }
        }
        if (!found) return result;

        result++;
    }
}
