source: mainline/uspace/dist/src/c/demos/edit/search.c@ f1380b7

/*
 * Copyright (c) 2012 Martin Sucha
 * 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.
 */

/** @addtogroup edit
 * @{
 */
/**
 * @file
 * @brief Simple searching facility.
 */

#include <stdlib.h>
#include <stddef.h>
#include <errno.h>

#include "search.h"
#include "search_impl.h"

search_t *search_init(const char *pattern, void *client_data, search_ops_t ops,
    bool reverse)
{
        search_t *search = calloc(1, sizeof(search_t));
        if (search == NULL)
                return NULL;

        wchar_t *p = str_to_awstr(pattern);
        if (p == NULL) {
                free(search);
                return NULL;
        }

        search->pattern_length = wstr_length(p);

        if (reverse) {
                /* Reverse the pattern */
                size_t pos, half;
                half = search->pattern_length / 2;
                for (pos = 0; pos < half; pos++) {
                        wchar_t tmp = p[pos];
                        p[pos] = p[search->pattern_length - pos - 1];
                        p[search->pattern_length - pos - 1] = tmp;
                }
        }

        search->pattern = p;

        search->client_data = client_data;
        search->ops = ops;
        search->back_table = calloc(search->pattern_length, sizeof(ssize_t));
        if (search->back_table == NULL) {
                free(search->pattern);
                free(search);
                return NULL;
        }

        search->pattern_pos = 0;

        search->back_table[0] = -1;
        search->back_table[1] = 0;
        size_t table_idx = 2;
        size_t pattern_idx = 0;
        while (table_idx < search->pattern_length) {
                if (ops.equals(search->pattern[table_idx - 1],
                    search->pattern[pattern_idx])) {
                        pattern_idx++;
                        search->back_table[table_idx] = pattern_idx;
                        table_idx++;
                }
                else if (pattern_idx > 0) {
                        pattern_idx = search->back_table[pattern_idx];
                }
                else {
                        pattern_idx = 0;
                        table_idx++;
                }
        }

        return search;
}

errno_t search_next_match(search_t *s, match_t *match)
{
        search_equals_fn eq = s->ops.equals;

        wchar_t cur_char;
        errno_t rc = EOK;
        while ((rc = s->ops.producer(s->client_data, &cur_char)) == EOK && cur_char > 0) {
                /* Deal with mismatches */
                while (s->pattern_pos > 0 && !eq(cur_char, s->pattern[s->pattern_pos])) {
                        s->pattern_pos = s->back_table[s->pattern_pos];
                }
                /* Check if the character matched */
                if (eq(cur_char, s->pattern[s->pattern_pos])) {
                        s->pattern_pos++;
                        if (s->pattern_pos == s->pattern_length) {
                                s->pattern_pos = s->back_table[s->pattern_pos];
                                rc = s->ops.mark(s->client_data, &match->end);
                                if (rc != EOK)
                                        return rc;
                                match->length = s->pattern_length;
                                return EOK;
                        }
                }
        }

        match->end = NULL;
        match->length = 0;

        return rc;
}

void search_fini(search_t *search)
{
        free(search->pattern);
        free(search->back_table);

}

bool char_exact_equals(const wchar_t a, const wchar_t b)
{
        return a == b;
}

/** @}
 */