path: root/libibex/words.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 * Copyright (C) 2000 Helix Code, Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with the Gnome Library; see the file COPYING.LIB.  If not,
 * write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

/* words.c: low-level indexing ops */

#include <ctype.h>
#include <errno.h>
#include <string.h>

#include <unicode.h>

#include "ibex_internal.h"

static signed char utf8_trans[] = {
    'A', 'A', 'A', 'A', 'A', 'A', -1, 'C', 'E', 'E', 'E', 'E', 'I', 'I',
    'I', 'I', -2, 'N', 'O', 'O', 'O', 'O', 'O', '*', 'O', 'U', 'U', 'U',
    'U', 'Y', -3, -4, 'a', 'a', 'a', 'a', 'a', 'a', -5, 'c', 'e', 'e',
    'e', 'e', 'i', 'i', 'i', 'i', -6, 'n', 'o', 'o', 'o', 'o', 'o', '/',
    'o', 'u', 'u', 'u', 'u', 'y', -7, 'y', 'A', 'a', 'A', 'a', 'A', 'a',
    'C', 'c', 'C', 'c', 'C', 'c', 'C', 'c', 'D', 'd', 'D', 'd', 'E', 'e',
    'E', 'e', 'E', 'e', 'E', 'e', 'E', 'e', 'G', 'g', 'G', 'g', 'G', 'g',
    'G', 'g', 'H', 'h', 'H', 'h', 'I', 'i', 'I', 'i', 'I', 'i', 'I', 'i',
    'I', 'i', -8, -9, 'J', 'j', 'K', 'k', 'k', 'L', 'l', 'L', 'l', 'L',
    'l', 'L', 'l', 'L', 'l', 'N', 'n', 'N', 'n', 'N', 'n', 'n', -10, -11,
    'O', 'o', 'O', 'o', 'O', 'o', -12, -13, 'R', 'r', 'R', 'r', 'R', 'r',
    'S', 'r', 'S', 's', 'S', 's', 'S', 's', 'T', 't', 'T', 't', 'T', 't',
    'U', 'u', 'U', 'u', 'U', 'u', 'U', 'u', 'U', 'u', 'U', 'u', 'W', 'w',
    'Y', 'y', 'Y', 'Z', 'z', 'Z', 'z', 'Z', 'z', 's'
};

static char *utf8_long_trans[] = {
    "AE", "TH", "TH", "ss", "ae", "th", "th", "IJ", "ij",
    "NG", "ng", "OE", "oe"
};

/* This is a bit weird. It takes pointers to the start and end (actually
 * just past the end) of a UTF-8-encoded word, and a buffer at least 1
 * byte longer than the length of the word. It copies the word into the
 * buffer in all lowercase without accents, and splits up ligatures.
 * (Since any ligature would be a multi-byte character in UTF-8, splitting
 * them into two US-ASCII characters won't overrun the buffer.)
 *
 * It is not safe to call this routine with bad UTF-8.
 */
static void
normalize_word (char *start, char *end, char *buf)
{
    unsigned char *s, *d;
    unicode_char_t uc;

    s = (unsigned char *)start;
    d = (unsigned char *)buf;
    while (s < (unsigned char *)end) {
        if (*s < 0x80) {
            /* US-ASCII character: copy unless it's
             * an apostrophe.
             */
            if (*s != '\'')
                *d++ = tolower (*s);
            s++;
        } else {
            char *next = unicode_get_utf8 (s, &uc);
            if (uc >= 0xc0 && uc < 0xc0 + sizeof (utf8_trans)) {
                signed char ch = utf8_trans[uc - 0xc0];
                if (ch > 0)
                    *d++ = tolower (ch);
                else {
                    *d++ = tolower (utf8_long_trans[-ch - 1][0]);
                    *d++ = tolower (utf8_long_trans[-ch - 1][1]);
                }
                s = next;
            } else {
                while (s < (unsigned char *)next)
                    *d++ = *s++;
            }
        }
    }
    *d = '\0';
}

enum { IBEX_ALPHA, IBEX_NONALPHA, IBEX_INVALID, IBEX_INCOMPLETE };

/* This incorporates parts of libunicode, because there's no way to
 * force libunicode to not read past a certain point.
 */
static int
utf8_category (char *sp, char **snp, char *send)
{
    unsigned char *p = (unsigned char *)sp, **np = (unsigned char **)snp;
    unsigned char *end = (unsigned char *)send;

    if (isascii (*p)) {
        *np = p + 1;
        if (isalpha (*p) || *p == '\'')
            return IBEX_ALPHA;
        return IBEX_NONALPHA;
    } else {
        unicode_char_t uc;
        int more;

        if ((*p & 0xe0) == 0xc0) {
            more = 1;
            uc = *p & 0x1f;
        } else if ((*p & 0xf0) == 0xe0) {
            more = 2;
            uc = *p & 0x0f;
        } else if ((*p & 0xf8) == 0xf0) {
            more = 3;
            uc = *p & 0x07;
        } else if ((*p & 0xfc) == 0xf8) {
            more = 4;
            uc = *p & 0x03;
        } else if ((*p & 0xfe) == 0xfc) {
            more = 5;
            uc = *p & 0x01;
        } else
            return IBEX_INVALID;

        if (p + more > end)
            return IBEX_INCOMPLETE;

        while (more--) {
            if ((*++p & 0xc0) != 0x80)
                return IBEX_INVALID;
            uc <<= 6;
            uc |= *p & 0x3f;
        }

        *np = p + 1;
        if (unicode_isalpha (uc))
            return IBEX_ALPHA;
        else
            return IBEX_NONALPHA;
    }
}

static ibex_file *
get_ibex_file (ibex *ib, char *name)
{
    ibex_file *ibf;

    ibf = g_tree_lookup (ib->files, name);
    if (!ibf) {
        ibf = g_malloc (sizeof (ibex_file));
        ibf->name = g_strdup (name);
        ibf->index = 0;
        g_tree_insert (ib->files, ibf->name, ibf);
        ib->dirty = TRUE;
    }
    return ibf;
}

static void
ref_word (ibex *ib, ibex_file *ibf, char *word)
{
    GPtrArray *refs;

    refs = g_hash_table_lookup (ib->words, word);
    if (!refs) {
        refs = g_ptr_array_new ();
        g_hash_table_insert (ib->words, g_strdup (word), refs);
        g_ptr_array_add (refs, ibf);
        ib->dirty = TRUE;
    } else if (g_ptr_array_index (refs, refs->len - 1) != ibf) {
        g_ptr_array_add (refs, ibf);
        ib->dirty = TRUE;
    }
}

/**
 * ibex_index_buffer: the lowest-level ibex indexing interface
 * @ib: an ibex
 * @name: the name of the file being indexed
 * @buffer: a buffer containing data from the file
 * @len: the length of @buffer
 * @unread: an output argument containing the number of unread bytes
 *
 * This routine indexes up to @len bytes from @buffer into @ib.
 * If @unread is NULL, the indexer assumes that the buffer ends on a
 * word boundary, and will index all the way to the end of the
 * buffer. If @unread is not NULL, and the buffer ends with an
 * alphabetic character, the indexer will assume that the buffer has
 * been cut off in the middle of a word, and return the number of
 * un-indexed bytes at the end of the buffer in *@unread. The caller
 * should then read in more data through whatever means it has
 * and pass in the unread bytes from the original buffer, followed
 * by the new data, on its next call.
 *
 * Return value: 0 on success, -1 on failure.
 **/
int
ibex_index_buffer (ibex *ib, char *name, char *buffer,
           size_t len, size_t *unread)
{
    char *p, *q, *nq, *end, *word;
    ibex_file *ibf = get_ibex_file (ib, name);
    int wordsiz, cat;

    if (unread)
        *unread = 0;

    end = buffer + len;
    wordsiz = 20;
    word = g_malloc (wordsiz);

    p = buffer;
    while (p < end) {
        while (p < end) {
            cat = utf8_category (p, &q, end);
            if (cat != IBEX_NONALPHA)
                break;
            p = q;
        }
        if (p == end) {
            g_free (word);
            return 0;
        } else if (cat == IBEX_INVALID) {
            errno = EINVAL;
            g_free (word);
            return -1;
        } else if (cat == IBEX_INCOMPLETE)
            q = end;

        while (q < end) {
            cat = utf8_category (q, &nq, end);
            if (cat != IBEX_ALPHA)
                break;
            q = nq;
        }
        if (cat == IBEX_INVALID ||
            (cat == IBEX_INCOMPLETE && !unread)) {
            errno = EINVAL;
            g_free (word);
            return -1;
        } else if (cat == IBEX_INCOMPLETE || (q == end && unread)) {
            *unread = end - p;
            g_free (word);
            return 0;
        }

        if (wordsiz < q - p + 1) {
            wordsiz = q - p + 1;
            word = g_realloc (word, wordsiz);
        }
        normalize_word (p, q, word);
        ref_word (ib, ibf, word);
        p = q;
    }

    g_free (word);
    return 0;
}