mariadb/myisam/ft_stopwords.c

/* Copyright (C) 2000-2011, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* Written by Sergei A. Golubchik, who has a shared copyright to this code */

#include "ftdefs.h"
#include "my_compare.h"

typedef struct st_ft_stopwords
{
  const char * pos;
  uint   len;
} FT_STOPWORD;

static TREE *stopwords3=NULL;

static int FT_STOPWORD_cmp(void* cmp_arg __attribute__((unused)),
			   FT_STOPWORD *w1, FT_STOPWORD *w2)
{
  return mi_compare_text(default_charset_info,
			 (uchar *)w1->pos,w1->len,
			 (uchar *)w2->pos,w2->len,0,0);
}

static void FT_STOPWORD_free(FT_STOPWORD *w, TREE_FREE action,
                             void *arg __attribute__((unused)))
{
  if (action == free_free)
    my_free((gptr) w->pos, MYF(0));
}

static int ft_add_stopword(const char *w)
{
  FT_STOPWORD sw;
  return !w ||
         (((sw.len= (uint) strlen(sw.pos=w)) >= ft_min_word_len) &&
          (tree_insert(stopwords3, &sw, 0, stopwords3->custom_arg)==NULL));
}

int ft_init_stopwords()
{
  if (!stopwords3)
  {
    if (!(stopwords3=(TREE *)my_malloc(sizeof(TREE),MYF(0))))
      return -1;
    init_tree(stopwords3,0,0,sizeof(FT_STOPWORD),(qsort_cmp2)&FT_STOPWORD_cmp,
              0,
              (ft_stopword_file ? (tree_element_free)&FT_STOPWORD_free : 0),
              NULL);
  }

  if (ft_stopword_file)
  {
    File fd;
    uint len;
    byte *buffer, *start, *end;
    FT_WORD w;
    int error=-1;

    if (!*ft_stopword_file)
      return 0;

    if ((fd=my_open(ft_stopword_file, O_RDONLY, MYF(MY_WME))) == -1)
      return -1;
    len=(uint)my_seek(fd, 0L, MY_SEEK_END, MYF(0));
    my_seek(fd, 0L, MY_SEEK_SET, MYF(0));
    if (!(start=buffer=my_malloc(len+1, MYF(MY_WME))))
      goto err0;
    len=my_read(fd, buffer, len, MYF(MY_WME));
    end=start+len;
    while (ft_simple_get_word(default_charset_info, &start, end, &w, TRUE))
    {
      if (ft_add_stopword(my_strdup_with_length(w.pos, w.len, MYF(0))))
        goto err1;
    }
    error=0;
err1:
    my_free(buffer, MYF(0));
err0:
    my_close(fd, MYF(MY_WME));
    return error;
  }
  else
  {
    /* compatibility mode: to be removed */
    char **sws=(char **)ft_precompiled_stopwords;

    for (;*sws;sws++)
    {
      if (ft_add_stopword(*sws))
        return -1;
    }
    ft_stopword_file="(built-in)"; /* for SHOW VARIABLES */
  }
  return 0;
}

int is_stopword(char *word, uint len)
{
  FT_STOPWORD sw;
  sw.pos=word;
  sw.len=len;
  return tree_search(stopwords3,&sw, stopwords3->custom_arg) != NULL;
}


void ft_free_stopwords()
{
  if (stopwords3)
  {
    delete_tree(stopwords3); /* purecov: inspected */
    my_free((char*) stopwords3,MYF(0));
    stopwords3=0;
  }
  ft_stopword_file= 0;
}