HelenOS sources

root/uspace/app/sbi/src/strtab.c

DEFINITIONS

1. strtab_init
2. strtab_get_sid
3. strtab_get_str

/*
 * Copyright (c) 2010 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @file String table.
 *
 * Converts strings to more compact SID (string ID, integer) and back.
 * (The point is that this deduplicates the strings. Using SID might actually
 * not be such a big win.)
 *
 * The string table is a singleton as there will never be a need for
 * more than one.
 *
 * Current implementation uses a linked list and thus it is slow.
 */

#include <stdlib.h>
#include "mytypes.h"
#include "os/os.h"
#include "list.h"

#include "strtab.h"

static list_t str_list;

/** Initialize string table. */
void strtab_init(void)
{
        list_init(&str_list);
}

/** Get SID of a string.
 *
 * Return SID of @a str. If @a str is not in the string table yet,
 * it is added and thus a new SID is assigned.
 *
 * @param str   String
 * @return      SID of @a str.
 */
sid_t strtab_get_sid(const char *str)
{
        list_node_t *node;
        sid_t sid;

        sid = 0;
        node = list_first(&str_list);

        while (node != NULL) {
                ++sid;
                if (os_str_cmp(str, list_node_data(node, char *)) == 0)
                        return sid;

                node = list_next(&str_list, node);
        }

        ++sid;
        list_append(&str_list, os_str_dup(str));

        return sid;
}

/** Get string with the given SID.
 *
 * Returns string that has SID @a sid. If no such string exists, this
 * causes a fatal error in the interpreter.
 *
 * @param sid   SID of the string.
 * @return      Pointer to the string.
 */
char *strtab_get_str(sid_t sid)
{
        list_node_t *node;
        sid_t cnt;

        node = list_first(&str_list);
        cnt = 1;
        while (node != NULL && cnt < sid) {
                node = list_next(&str_list, node);
                cnt += 1;
        }

        if (node == NULL) {
                printf("Internal error: Invalid SID %d", sid);
                abort();
        }

        return list_node_data(node, char *);
}