/* Init a replace structure for further calls */

REPLACE *init_replace(char * *from, char * *to,uint count,
		      char * word_end_chars)
{
  static const int SPACE_CHAR= 256;
  static const int END_OF_LINE= 258;

  uint i,j,states,set_nr,len,result_len,max_length,found_end,bits_set,bit_nr;
  int used_sets,chr,default_state;
  char used_chars[LAST_CHAR_CODE],is_word_end[256];
  char * pos, *to_pos, **to_array;
  REP_SETS sets;
  REP_SET *set,*start_states,*word_states,*new_set;
  FOLLOWS *follow,*follow_ptr;
  REPLACE *replace;
  FOUND_SET *found_set;
  REPLACE_STRING *rep_str;
  DBUG_ENTER("init_replace");

  /* Count number of states */
  for (i=result_len=max_length=0 , states=2 ; i < count ; i++)
  {
    len=replace_len(from[i]);
    if (!len)
    {
      errno=EINVAL;
      DBUG_RETURN(0);
    }
    states+=len+1;
    result_len+=(uint) strlen(to[i])+1;
    if (len > max_length)
      max_length=len;
  }
  memset(is_word_end, 0, sizeof(is_word_end));
  for (i=0 ; word_end_chars[i] ; i++)
    is_word_end[(uchar) word_end_chars[i]]=1;

  if (init_sets(&sets,states))
    DBUG_RETURN(0);
  found_sets=0;
  if (!(found_set= (FOUND_SET*) my_malloc(sizeof(FOUND_SET)*max_length*count,
					  MYF(MY_WME))))
  {
    free_sets(&sets);
    DBUG_RETURN(0);
  }
  (void) make_new_set(&sets);			/* Set starting set */
  make_sets_invisible(&sets);			/* Hide previus sets */
  used_sets=-1;
  word_states=make_new_set(&sets);		/* Start of new word */
  start_states=make_new_set(&sets);		/* This is first state */
  if (!(follow=(FOLLOWS*) my_malloc((states+2)*sizeof(FOLLOWS),MYF(MY_WME))))
  {
    free_sets(&sets);
    my_free(found_set);
    DBUG_RETURN(0);
  }

  /* Init follow_ptr[] */
  for (i=0, states=1, follow_ptr=follow+1 ; i < count ; i++)
  {
    if (from[i][0] == '\\' && from[i][1] == '^')
    {
      internal_set_bit(start_states,states+1);
      if (!from[i][2])
      {
	start_states->table_offset=i;
	start_states->found_offset=1;
      }
    }
    else if (from[i][0] == '\\' && from[i][1] == '$')
    {
      internal_set_bit(start_states,states);
      internal_set_bit(word_states,states);
      if (!from[i][2] && start_states->table_offset == (uint) ~0)
      {
	start_states->table_offset=i;
	start_states->found_offset=0;
      }
    }
    else
    {
      internal_set_bit(word_states,states);
      if (from[i][0] == '\\' && (from[i][1] == 'b' && from[i][2]))
	internal_set_bit(start_states,states+1);
      else
	internal_set_bit(start_states,states);
    }
    for (pos=from[i], len=0; *pos ; pos++)
    {
      follow_ptr->chr= (uchar) *pos;
      follow_ptr->table_offset=i;
      follow_ptr->len= ++len;
      follow_ptr++;
    }
    follow_ptr->chr=0;
    follow_ptr->table_offset=i;
    follow_ptr->len=len;
    follow_ptr++;
    states+=(uint) len+1;
  }


  for (set_nr=0,pos=0 ; set_nr < sets.count ; set_nr++)
  {
    set=sets.set+set_nr;
    default_state= 0;				/* Start from beginning */

    /* If end of found-string not found or start-set with current set */

    for (i= (uint) ~0; (i=get_next_bit(set,i)) ;)
    {
      if (!follow[i].chr)
      {
	if (! default_state)
	  default_state= find_found(found_set,set->table_offset,
				    set->found_offset+1);
      }
    }
    copy_bits(sets.set+used_sets,set);		/* Save set for changes */
    if (!default_state)
      or_bits(sets.set+used_sets,sets.set);	/* Can restart from start */

    /* Find all chars that follows current sets */
    memset(used_chars, 0, sizeof(used_chars));
    for (i= (uint) ~0; (i=get_next_bit(sets.set+used_sets,i)) ;)
    {
      used_chars[follow[i].chr]=1;
      if ((follow[i].chr == SPACE_CHAR && !follow[i+1].chr &&
	   follow[i].len > 1) || follow[i].chr == END_OF_LINE)
	used_chars[0]=1;
    }

    /* Mark word_chars used if \b is in state */
    if (used_chars[SPACE_CHAR])
      for (pos= word_end_chars ; *pos ; pos++)
	used_chars[(int) (uchar) *pos] = 1;

    /* Handle other used characters */
    for (chr= 0 ; chr < 256 ; chr++)
    {
      if (! used_chars[chr])
	set->next[chr]= chr ? default_state : -1;
      else
      {
	new_set=make_new_set(&sets);
        assert(new_set);
	set=sets.set+set_nr;			/* if realloc */
	new_set->table_offset=set->table_offset;
	new_set->found_len=set->found_len;
	new_set->found_offset=set->found_offset+1;
	found_end=0;

	for (i= (uint) ~0 ; (i=get_next_bit(sets.set+used_sets,i)) ; )
	{
	  if (!follow[i].chr || follow[i].chr == chr ||
	      (follow[i].chr == SPACE_CHAR &&
	       (is_word_end[chr] ||
		(!chr && follow[i].len > 1 && ! follow[i+1].chr))) ||
	      (follow[i].chr == END_OF_LINE && ! chr))
	  {
	    if ((! chr || (follow[i].chr && !follow[i+1].chr)) &&
		follow[i].len > found_end)
	      found_end=follow[i].len;
	    if (chr && follow[i].chr)
	      internal_set_bit(new_set,i+1);		/* To next set */
	    else
	      internal_set_bit(new_set,i);
	  }
	}
	if (found_end)
	{
	  new_set->found_len=0;			/* Set for testing if first */
	  bits_set=0;
	  for (i= (uint) ~0; (i=get_next_bit(new_set,i)) ;)
	  {
	    if ((follow[i].chr == SPACE_CHAR ||
		 follow[i].chr == END_OF_LINE) && ! chr)
	      bit_nr=i+1;
	    else
	      bit_nr=i;
	    if (follow[bit_nr-1].len < found_end ||
		(new_set->found_len &&
		 (chr == 0 || !follow[bit_nr].chr)))
	      internal_clear_bit(new_set,i);
	    else
	    {
	      if (chr == 0 || !follow[bit_nr].chr)
	      {					/* best match  */
		new_set->table_offset=follow[bit_nr].table_offset;
		if (chr || (follow[i].chr == SPACE_CHAR ||
			    follow[i].chr == END_OF_LINE))
		  new_set->found_offset=found_end;	/* New match */
		new_set->found_len=found_end;
	      }
	      bits_set++;
	    }
	  }
	  if (bits_set == 1)
	  {
	    set->next[chr] = find_found(found_set,
					new_set->table_offset,
					new_set->found_offset);
	    free_last_set(&sets);
	  }
	  else
	    set->next[chr] = find_set(&sets,new_set);
	}
	else
	  set->next[chr] = find_set(&sets,new_set);
      }
    }
  }

  /* Alloc replace structure for the replace-state-machine */

  if ((replace=(REPLACE*) my_malloc(sizeof(REPLACE)*(sets.count)+
				    sizeof(REPLACE_STRING)*(found_sets+1)+
				    sizeof(char *)*count+result_len,
				    MYF(MY_WME | MY_ZEROFILL))))
  {
    rep_str=(REPLACE_STRING*) (replace+sets.count);
    to_array= (char **) (rep_str+found_sets+1);
    to_pos=(char *) (to_array+count);
    for (i=0 ; i < count ; i++)
    {
      to_array[i]=to_pos;
      to_pos=strmov(to_pos,to[i])+1;
    }
    rep_str[0].found=1;
    rep_str[0].replace_string=0;
    for (i=1 ; i <= found_sets ; i++)
    {
      pos=from[found_set[i-1].table_offset];
      rep_str[i].found= !memcmp(pos, "\\^", 3) ? 2 : 1;
      rep_str[i].replace_string=to_array[found_set[i-1].table_offset];
      rep_str[i].to_offset=found_set[i-1].found_offset-start_at_word(pos);
      rep_str[i].from_offset=found_set[i-1].found_offset-replace_len(pos)+
	end_of_word(pos);
    }
    for (i=0 ; i < sets.count ; i++)
    {
      for (j=0 ; j < 256 ; j++)
	if (sets.set[i].next[j] >= 0)
	  replace[i].next[j]=replace+sets.set[i].next[j];
	else
	  replace[i].next[j]=(REPLACE*) (rep_str+(-sets.set[i].next[j]-1));
    }
  }
  my_free(follow);
  free_sets(&sets);
  my_free(found_set);
  DBUG_PRINT("exit",("Replace table has %d states",sets.count));