/* Copyright (C) 2001-2005 MySQL AB

   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 */

/*  TODO: add caching - pre-read several index entries at once */

#define FT_CORE
#include "ftdefs.h"

/* search with boolean queries */

static double _wghts[11]=
{
  0.131687242798354,
  0.197530864197531,
  0.296296296296296,
  0.444444444444444,
  0.666666666666667,
  1.000000000000000,
  1.500000000000000,
  2.250000000000000,
  3.375000000000000,
  5.062500000000000,
  7.593750000000000};
static double *wghts=_wghts+5; /* wghts[i] = 1.5**i */

static double _nwghts[11]=
{
 -0.065843621399177,
 -0.098765432098766,
 -0.148148148148148,
 -0.222222222222222,
 -0.333333333333334,
 -0.500000000000000,
 -0.750000000000000,
 -1.125000000000000,
 -1.687500000000000,
 -2.531250000000000,
 -3.796875000000000};
static double *nwghts=_nwghts+5; /* nwghts[i] = -0.5*1.5**i */

#define FTB_FLAG_TRUNC 1
/* At most one of the following flags can be set */
#define FTB_FLAG_YES   2
#define FTB_FLAG_NO    4
#define FTB_FLAG_WONLY 8

typedef struct st_ftb_expr FTB_EXPR;
struct st_ftb_expr
{
  FTB_EXPR *up;
  uint      flags;
/* ^^^^^^^^^^^^^^^^^^ FTB_{EXPR,WORD} common section */
  my_off_t  docid[2];
  float     weight;
  float     cur_weight;
  LIST     *phrase;               /* phrase words */
  uint      yesses;               /* number of "yes" words matched */
  uint      nos;                  /* number of "no"  words matched */
  uint      ythresh;              /* number of "yes" words in expr */
  uint      yweaks;               /* number of "yes" words for scan only */
};

typedef struct st_ftb_word
{
  FTB_EXPR  *up;
  uint       flags;
/* ^^^^^^^^^^^^^^^^^^ FTB_{EXPR,WORD} common section */
  my_off_t   docid[2];             /* for index search and for scan */
  my_off_t   key_root;
  MI_KEYDEF *keyinfo;
  float      weight;
  uint       ndepth;
  uint       len;
  uchar      off;
  byte       word[1];
} FTB_WORD;

typedef struct st_ft_info
{
  struct _ft_vft *please;
  MI_INFO   *info;
  CHARSET_INFO *charset;
  FTB_EXPR  *root;
  FTB_WORD **list;
  MEM_ROOT   mem_root;
  QUEUE      queue;
  TREE       no_dupes;
  my_off_t   lastpos;
  uint       keynr;
  uchar      with_scan;
  enum { UNINITIALIZED, READY, INDEX_SEARCH, INDEX_DONE } state;
} FTB;

static int FTB_WORD_cmp(my_off_t *v, FTB_WORD *a, FTB_WORD *b)
{
  int i;

  /* if a==curdoc, take it as  a < b */
  if (v && a->docid[0] == *v)
    return -1;

  /* ORDER BY docid, ndepth DESC */
  i=CMP_NUM(a->docid[0], b->docid[0]);
  if (!i)
    i=CMP_NUM(b->ndepth,a->ndepth);
  return i;
}

static int FTB_WORD_cmp_list(CHARSET_INFO *cs, FTB_WORD **a, FTB_WORD **b)
{
  /* ORDER BY word, ndepth */
  int i= mi_compare_text(cs, (uchar*) (*a)->word + 1, (*a)->len - 1,
                             (uchar*) (*b)->word + 1, (*b)->len - 1, 0, 0);
  if (!i)
    i= CMP_NUM((*a)->ndepth, (*b)->ndepth);
  return i;
}

static void _ftb_parse_query(FTB *ftb, byte **start, byte *end,
                      FTB_EXPR *up, uint depth, byte *up_quot)
{
  byte        res;
  FTB_PARAM   param;
  FT_WORD     w;
  FTB_WORD   *ftbw;
  FTB_EXPR   *ftbe;
  FT_WORD    *phrase_word;
  LIST       *phrase_list;
  uint  extra=HA_FT_WLEN+ftb->info->s->rec_reflength; /* just a shortcut */

  if (ftb->state != UNINITIALIZED)
    return;

  param.prev=' ';
  param.quot= up_quot;
  while ((res=ft_get_word(ftb->charset,start,end,&w,&param)))
  {
    int   r=param.plusminus;
    float weight= (float) (param.pmsign ? nwghts : wghts)[(r>5)?5:((r<-5)?-5:r)];
    switch (res) {
      case 1: /* word found */
        ftbw=(FTB_WORD *)alloc_root(&ftb->mem_root,
                                    sizeof(FTB_WORD) +
                                    (param.trunc ? MI_MAX_KEY_BUFF :
                                     w.len*ftb->charset->mbmaxlen+extra));
        ftbw->len=w.len+1;
        ftbw->flags=0;
        ftbw->off=0;
        if (param.yesno>0) ftbw->flags|=FTB_FLAG_YES;
        if (param.yesno<0) ftbw->flags|=FTB_FLAG_NO;
        if (param.trunc)   ftbw->flags|=FTB_FLAG_TRUNC;
        ftbw->weight=weight;
        ftbw->up=up;
        ftbw->docid[0]=ftbw->docid[1]=HA_OFFSET_ERROR;
        ftbw->ndepth= (param.yesno<0) + depth;
        ftbw->key_root=HA_OFFSET_ERROR;
        memcpy(ftbw->word+1, w.pos, w.len);
        ftbw->word[0]=w.len;
        if (param.yesno > 0) up->ythresh++;
        queue_insert(& ftb->queue, (byte *)ftbw);
        ftb->with_scan|=(param.trunc & FTB_FLAG_TRUNC);
      case 4: /* not indexed word (stopword or too short/long) */
        if (! up_quot) break;
        phrase_word= (FT_WORD *)alloc_root(&ftb->mem_root, sizeof(FT_WORD));
        phrase_list= (LIST *)alloc_root(&ftb->mem_root, sizeof(LIST));
        phrase_word->pos= w.pos;
        phrase_word->len= w.len;
        phrase_list->data= (void *)phrase_word;
        up->phrase= list_add(up->phrase, phrase_list);
        break;
      case 2: /* left bracket */
        ftbe=(FTB_EXPR *)alloc_root(&ftb->mem_root, sizeof(FTB_EXPR));
        ftbe->flags=0;
        if (param.yesno>0) ftbe->flags|=FTB_FLAG_YES;
        if (param.yesno<0) ftbe->flags|=FTB_FLAG_NO;
        ftbe->weight=weight;
        ftbe->up=up;
        ftbe->ythresh=ftbe->yweaks=0;
        ftbe->docid[0]=ftbe->docid[1]=HA_OFFSET_ERROR;
        ftbe->phrase= NULL;
        if (param.quot) ftb->with_scan|=2;
        if (param.yesno > 0) up->ythresh++;
        _ftb_parse_query(ftb, start, end, ftbe, depth+1, param.quot);
        param.quot=0;
        break;
      case 3: /* right bracket */
        if (up_quot) up->phrase= list_reverse(up->phrase);
        return;
    }
  }
  return;
}

static int _ftb_no_dupes_cmp(void* not_used __attribute__((unused)),
                             const void *a,const void *b)
{
  return CMP_NUM((*((my_off_t*)a)), (*((my_off_t*)b)));
}

/* returns 1 if the search was finished (must-word wasn't found) */
static int _ft2_search(FTB *ftb, FTB_WORD *ftbw, my_bool init_search)
{
  int r;
  int subkeys=1;
  my_bool can_go_down;
  MI_INFO *info=ftb->info;
  uint off, extra=HA_FT_WLEN+info->s->base.rec_reflength;
  byte *lastkey_buf=ftbw->word+ftbw->off;
  LINT_INIT(off);

  LINT_INIT(off);
  if (ftbw->flags & FTB_FLAG_TRUNC)
    lastkey_buf+=ftbw->len;

  if (init_search)
  {
    ftbw->key_root=info->s->state.key_root[ftb->keynr];
    ftbw->keyinfo=info->s->keyinfo+ftb->keynr;

    r=_mi_search(info, ftbw->keyinfo, (uchar*) ftbw->word, ftbw->len,
                 SEARCH_FIND | SEARCH_BIGGER, ftbw->key_root);
  }
  else
  {
    r=_mi_search(info, ftbw->keyinfo, (uchar*) lastkey_buf,
                   USE_WHOLE_KEY, SEARCH_BIGGER, ftbw->key_root);
  }

  can_go_down=(!ftbw->off && (init_search || (ftbw->flags & FTB_FLAG_TRUNC)));
  /* Skip rows inserted by concurrent insert */
  while (!r)
  {
    if (can_go_down)
    {
      /* going down ? */
      off=info->lastkey_length-extra;
      subkeys=ft_sintXkorr(info->lastkey+off);
    }
    if (subkeys<0 || info->lastpos < info->state->data_file_length)
      break;
    r= _mi_search_next(info, ftbw->keyinfo, info->lastkey,
                       info->lastkey_length,
		       SEARCH_BIGGER, ftbw->key_root);
  }

  if (!r && !ftbw->off)
  {
    r= mi_compare_text(ftb->charset,
                       info->lastkey+1,
                       info->lastkey_length-extra-1,
              (uchar*) ftbw->word+1,
                       ftbw->len-1,
             (my_bool) (ftbw->flags & FTB_FLAG_TRUNC),0);
  }

  if (r) /* not found */
  {
    if (!ftbw->off || !(ftbw->flags & FTB_FLAG_TRUNC))
    {
      ftbw->docid[0]=HA_OFFSET_ERROR;
      if ((ftbw->flags & FTB_FLAG_YES) && ftbw->up->up==0)
      {
        /*
          This word MUST BE present in every document returned,
          so we can stop the search right now
        */
        ftb->state=INDEX_DONE;
        return 1; /* search is done */
      }
      else
        return 0;
    }

    /* going up to the first-level tree to continue search there */
    _mi_dpointer(info, (uchar*) (lastkey_buf+HA_FT_WLEN), ftbw->key_root);
    ftbw->key_root=info->s->state.key_root[ftb->keynr];
    ftbw->keyinfo=info->s->keyinfo+ftb->keynr;
    ftbw->off=0;
    return _ft2_search(ftb, ftbw, 0);
  }

  /* matching key found */
  memcpy(lastkey_buf, info->lastkey, info->lastkey_length);
  if (lastkey_buf == ftbw->word)
    ftbw->len=info->lastkey_length-extra;

  /* going down ? */
  if (subkeys<0)
  {
    /*
      yep, going down, to the second-level tree
      TODO here: subkey-based optimization
    */
    ftbw->off=off;
    ftbw->key_root=info->lastpos;
    ftbw->keyinfo=& info->s->ft2_keyinfo;
    r=_mi_search_first(info, ftbw->keyinfo, ftbw->key_root);
    DBUG_ASSERT(r==0);  /* found something */
    memcpy(lastkey_buf+off, info->lastkey, info->lastkey_length);
  }
  ftbw->docid[0]=info->lastpos;
  return 0;
}

static void _ftb_init_index_search(FT_INFO *ftb)
{
  int i;
  FTB_WORD   *ftbw;

  if ((ftb->state != READY && ftb->state !=INDEX_DONE) ||
      ftb->keynr == NO_SUCH_KEY)
    return;
  ftb->state=INDEX_SEARCH;

  for (i=ftb->queue.elements; i; i--)
  {
    ftbw=(FTB_WORD *)(ftb->queue.root[i]);

    if (ftbw->flags & FTB_FLAG_TRUNC)
    {
      /*
        special treatment for truncation operator
        1. there are some (besides this) +words
           | no need to search in the index, it can never ADD new rows
           | to the result, and to remove half-matched rows we do scan anyway
        2. -trunc*
           | same as 1.
        3. in 1 and 2, +/- need not be on the same expr. level,
           but can be on any upper level, as in +word +(trunc1* trunc2*)
        4. otherwise
           | We have to index-search for this prefix.
           | It may cause duplicates, as in the index (sorted by <word,docid>)
           |   <aaaa,row1>
           |   <aabb,row2>
           |   <aacc,row1>
           | Searching for "aa*" will find row1 twice...
      */
      FTB_EXPR *ftbe;
      for (ftbe=(FTB_EXPR*)ftbw;
           ftbe->up && !(ftbe->up->flags & FTB_FLAG_TRUNC);
           ftbe->up->flags|= FTB_FLAG_TRUNC, ftbe=ftbe->up)
      {
        if (ftbe->flags & FTB_FLAG_NO ||                     /* 2 */
             ftbe->up->ythresh - ftbe->up->yweaks >1)        /* 1 */
        {
          FTB_EXPR *top_ftbe=ftbe->up;
          ftbw->docid[0]=HA_OFFSET_ERROR;
          for (ftbe=(FTB_EXPR *)ftbw;
               ftbe != top_ftbe && !(ftbe->flags & FTB_FLAG_NO);
               ftbe=ftbe->up)
              ftbe->up->yweaks++;
          ftbe=0;
          break;
        }
      }
      if (!ftbe)
        continue;
      /* 4 */
      if (!is_tree_inited(& ftb->no_dupes))
        init_tree(& ftb->no_dupes,0,0,sizeof(my_off_t),
            _ftb_no_dupes_cmp,0,0,0);
      else
        reset_tree(& ftb->no_dupes);
    }

    ftbw->off=0; /* in case of reinit */
    if (_ft2_search(ftb, ftbw, 1))
      return;
  }
  queue_fix(& ftb->queue);
}


FT_INFO * ft_init_boolean_search(MI_INFO *info, uint keynr, byte *query,
                                 uint query_len, CHARSET_INFO *cs)
{
  FTB       *ftb;
  FTB_EXPR  *ftbe;
  uint       res;

  if (!(ftb=(FTB *)my_malloc(sizeof(FTB), MYF(MY_WME))))
    return 0;
  ftb->please= (struct _ft_vft *) & _ft_vft_boolean;
  ftb->state=UNINITIALIZED;
  ftb->info=info;
  ftb->keynr=keynr;
  ftb->charset=cs;
  DBUG_ASSERT(keynr==NO_SUCH_KEY || cs == info->s->keyinfo[keynr].seg->charset);
  ftb->with_scan=0;
  ftb->lastpos=HA_OFFSET_ERROR;
  bzero(& ftb->no_dupes, sizeof(TREE));

  init_alloc_root(&ftb->mem_root, 1024, 1024);

  /*
    Hack: instead of init_queue, we'll use reinit queue to be able
    to alloc queue with alloc_root()
  */
  res=ftb->queue.max_elements=1+query_len/2;
  if (!(ftb->queue.root=
        (byte **)alloc_root(&ftb->mem_root, (res+1)*sizeof(void*))))
    goto err;
  reinit_queue(& ftb->queue, res, 0, 0,
                         (int (*)(void*,byte*,byte*))FTB_WORD_cmp, 0);
  if (!(ftbe=(FTB_EXPR *)alloc_root(&ftb->mem_root, sizeof(FTB_EXPR))))
    goto err;
  ftbe->weight=1;
  ftbe->flags=FTB_FLAG_YES;
  ftbe->nos=1;
  ftbe->up=0;
  ftbe->ythresh=ftbe->yweaks=0;
  ftbe->docid[0]=ftbe->docid[1]=HA_OFFSET_ERROR;
  ftbe->phrase= NULL;
  ftb->root=ftbe;
  _ftb_parse_query(ftb, &query, query+query_len, ftbe, 0, NULL);
  ftb->list=(FTB_WORD **)alloc_root(&ftb->mem_root,
                                     sizeof(FTB_WORD *)*ftb->queue.elements);
  memcpy(ftb->list, ftb->queue.root+1, sizeof(FTB_WORD *)*ftb->queue.elements);
  my_qsort2(ftb->list, ftb->queue.elements, sizeof(FTB_WORD *),
            (qsort2_cmp)FTB_WORD_cmp_list, ftb->charset);
  if (ftb->queue.elements<2) ftb->with_scan &= ~FTB_FLAG_TRUNC;
  ftb->state=READY;
  return ftb;
err:
  free_root(& ftb->mem_root, MYF(0));
  my_free((gptr)ftb,MYF(0));
  return 0;
}


/*
  Checks if given buffer matches phrase list.

  SYNOPSIS
    _ftb_check_phrase()
    s0     start of buffer
    e0     end of buffer
    phrase broken into list phrase
    cs     charset info

  RETURN VALUE
    1 is returned if phrase found, 0 else.
*/

static int _ftb_check_phrase(const byte *s0, const byte *e0,
                LIST *phrase, CHARSET_INFO *cs)
{
  FT_WORD h_word;
  const byte *h_start= s0;
  DBUG_ENTER("_ftb_strstr");
  DBUG_ASSERT(phrase);

  while (ft_simple_get_word(cs, (byte **)&h_start, e0, &h_word, FALSE))
  {
    FT_WORD *n_word;
    LIST *phrase_element= phrase;
    const byte *h_start1= h_start;
    for (;;)
    {
      n_word= (FT_WORD *)phrase_element->data;
      if (my_strnncoll(cs, (const uchar *) h_word.pos, h_word.len,
		       (const uchar *) n_word->pos, n_word->len))
        break;
      if (! (phrase_element= phrase_element->next))
        DBUG_RETURN(1);
      if (! ft_simple_get_word(cs, (byte **)&h_start1, e0, &h_word, FALSE))
        DBUG_RETURN(0);
    }
  }
  DBUG_RETURN(0);
}


static void _ftb_climb_the_tree(FTB *ftb, FTB_WORD *ftbw, FT_SEG_ITERATOR *ftsi_orig)
{
  FT_SEG_ITERATOR ftsi;
  FTB_EXPR *ftbe;
  float weight=ftbw->weight;
  int  yn_flag= ftbw->flags, ythresh, mode=(ftsi_orig != 0);
  my_off_t curdoc=ftbw->docid[mode];

  for (ftbe=ftbw->up; ftbe; ftbe=ftbe->up)
  {
    ythresh = ftbe->ythresh - (mode ? 0 : ftbe->yweaks);
    if (ftbe->docid[mode] != curdoc)
    {
      ftbe->cur_weight=0;
      ftbe->yesses=ftbe->nos=0;
      ftbe->docid[mode]=curdoc;
    }
    if (ftbe->nos)
      break;
    if (yn_flag & FTB_FLAG_YES)
    {
      weight /= ftbe->ythresh;
      ftbe->cur_weight += weight;
      if ((int) ++ftbe->yesses == ythresh)
      {
        yn_flag=ftbe->flags;
        weight=ftbe->cur_weight*ftbe->weight;
        if (mode && ftbe->phrase)
        {
          int not_found=1;

          memcpy(&ftsi, ftsi_orig, sizeof(ftsi));
          while (_mi_ft_segiterator(&ftsi) && not_found)
          {
            if (!ftsi.pos)
              continue;
            not_found = ! _ftb_check_phrase(ftsi.pos, ftsi.pos+ftsi.len,
                                      ftbe->phrase, ftb->charset);
          }
          if (not_found) break;
        } /* ftbe->quot */
      }
      else
        break;
    }
    else
    if (yn_flag & FTB_FLAG_NO)
    {
      /*
        NOTE: special sort function of queue assures that all
        (yn_flag & FTB_FLAG_NO) != 0
        events for every particular subexpression will
        "auto-magically" happen BEFORE all the
        (yn_flag & FTB_FLAG_YES) != 0 events. So no
        already matched expression can become not-matched again.
      */
      ++ftbe->nos;
      break;
    }
    else
    {
      if (ftbe->ythresh)
        weight/=3;
      ftbe->cur_weight +=  weight;
      if ((int) ftbe->yesses < ythresh)
        break;
      if (!(yn_flag & FTB_FLAG_WONLY))
        yn_flag= ((int) ftbe->yesses++ == ythresh) ? ftbe->flags : FTB_FLAG_WONLY ;
      weight*= ftbe->weight;
    }
  }
}


int ft_boolean_read_next(FT_INFO *ftb, char *record)
{
  FTB_EXPR  *ftbe;
  FTB_WORD  *ftbw;
  MI_INFO   *info=ftb->info;
  my_off_t   curdoc;

  if (ftb->state != INDEX_SEARCH && ftb->state != INDEX_DONE)
    return -1;

  /* black magic ON */
  if ((int) _mi_check_index(info, ftb->keynr) < 0)
    return my_errno;
  if (_mi_readinfo(info, F_RDLCK, 1))
    return my_errno;
  /* black magic OFF */

  if (!ftb->queue.elements)
    return my_errno=HA_ERR_END_OF_FILE;

  /* Attention!!! Address of a local variable is used here! See err: label */
  ftb->queue.first_cmp_arg=(void *)&curdoc;

  while (ftb->state == INDEX_SEARCH &&
         (curdoc=((FTB_WORD *)queue_top(& ftb->queue))->docid[0]) !=
         HA_OFFSET_ERROR)
  {
    while (curdoc == (ftbw=(FTB_WORD *)queue_top(& ftb->queue))->docid[0])
    {
      _ftb_climb_the_tree(ftb, ftbw, 0);

      /* update queue */
      _ft2_search(ftb, ftbw, 0);
      queue_replaced(& ftb->queue);
    }

    ftbe=ftb->root;
    if (ftbe->docid[0]==curdoc && ftbe->cur_weight>0 &&
        ftbe->yesses>=(ftbe->ythresh-ftbe->yweaks) && !ftbe->nos)
    {
      /* curdoc matched ! */
      if (is_tree_inited(&ftb->no_dupes) &&
          tree_insert(&ftb->no_dupes, &curdoc, 0,
                      ftb->no_dupes.custom_arg)->count >1)
        /* but it managed already to get past this line once */
        continue;

      info->lastpos=curdoc;
      /* Clear all states, except that the table was updated */
      info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);

      if (!(*info->read_record)(info,curdoc,record))
      {
        info->update|= HA_STATE_AKTIV;          /* Record is read */
        if (ftb->with_scan && ft_boolean_find_relevance(ftb,record,0)==0)
            continue; /* no match */
        my_errno=0;
        goto err;
      }
      goto err;
    }
  }
  ftb->state=INDEX_DONE;
  my_errno=HA_ERR_END_OF_FILE;
err:
  ftb->queue.first_cmp_arg=(void *)0;
  return my_errno;
}


float ft_boolean_find_relevance(FT_INFO *ftb, byte *record, uint length)
{
  FT_WORD word;
  FTB_WORD *ftbw;
  FTB_EXPR *ftbe;
  FT_SEG_ITERATOR ftsi, ftsi2;
  const byte *end;
  my_off_t  docid=ftb->info->lastpos;

  if (docid == HA_OFFSET_ERROR)
    return -2.0;
  if (!ftb->queue.elements)
    return 0;

  if (ftb->state != INDEX_SEARCH && docid <= ftb->lastpos)
  {
    FTB_EXPR *x;
    uint i;

    for (i=0; i < ftb->queue.elements; i++)
    {
      ftb->list[i]->docid[1]=HA_OFFSET_ERROR;
      for (x=ftb->list[i]->up; x; x=x->up)
        x->docid[1]=HA_OFFSET_ERROR;
    }
  }

  ftb->lastpos=docid;

  if (ftb->keynr==NO_SUCH_KEY)
    _mi_ft_segiterator_dummy_init(record, length, &ftsi);
  else
    _mi_ft_segiterator_init(ftb->info, ftb->keynr, record, &ftsi);
  memcpy(&ftsi2, &ftsi, sizeof(ftsi));

  while (_mi_ft_segiterator(&ftsi))
  {
    if (!ftsi.pos)
      continue;

    end=ftsi.pos+ftsi.len;
    while (ft_simple_get_word(ftb->charset, (byte **) &ftsi.pos,
                              (byte *) end, &word, TRUE))
    {
      int a, b, c;
      /*
        Find right-most element in the array of query words matching this
        word from a document.
      */
      for (a=0, b=ftb->queue.elements, c=(a+b)/2; b-a>1; c=(a+b)/2)
      {
        ftbw=ftb->list[c];
        if (mi_compare_text(ftb->charset, (uchar*) word.pos, word.len,
                            (uchar*) ftbw->word+1, ftbw->len-1,
                            (my_bool) (ftbw->flags & FTB_FLAG_TRUNC), 0) < 0)
          b=c;
        else
          a=c;
      }
      /*
        If there were no words with truncation operator, we iterate to the
        beginning of an array until array element is equal to the word from
        a document. This is done mainly because the same word may be
        mentioned twice (or more) in the query.

        In case query has words with truncation operator we must iterate
        to the beginning of the array. There may be non-matching query words
        between matching word with truncation operator and the right-most
        matching element. E.g., if we're looking for 'aaa15' in an array of
        'aaa1* aaa14 aaa15 aaa16'.

        Worse of that there still may be match even if the binary search
        above didn't find matching element. E.g., if we're looking for
        'aaa15' in an array of 'aaa1* aaa14 aaa16'. The binary search will
        stop at 'aaa16'.
      */
      for (; c>=0; c--)
      {
        ftbw=ftb->list[c];
        if (mi_compare_text(ftb->charset, (uchar*) word.pos, word.len,
                            (uchar*) ftbw->word+1,ftbw->len-1,
                            (my_bool) (ftbw->flags&FTB_FLAG_TRUNC),0))
        {
          if (ftb->with_scan & FTB_FLAG_TRUNC)
            continue;
          else
            break;
        }
        if (ftbw->docid[1] == docid)
          continue;
        ftbw->docid[1]=docid;
        _ftb_climb_the_tree(ftb, ftbw, &ftsi2);
      }
    }
  }

  ftbe=ftb->root;
  if (ftbe->docid[1]==docid && ftbe->cur_weight>0 &&
      ftbe->yesses>=ftbe->ythresh && !ftbe->nos)
  { /* row matched ! */
    return ftbe->cur_weight;
  }
  else
  { /* match failed ! */
    return 0.0;
  }
}


void ft_boolean_close_search(FT_INFO *ftb)
{
  if (is_tree_inited(& ftb->no_dupes))
  {
    delete_tree(& ftb->no_dupes);
  }
  free_root(& ftb->mem_root, MYF(0));
  my_free((gptr)ftb,MYF(0));
}


float ft_boolean_get_relevance(FT_INFO *ftb)
{
  return ftb->root->cur_weight;
}


void ft_boolean_reinit_search(FT_INFO *ftb)
{
  _ftb_init_index_search(ftb);
}