SQLite

** into the current action table.  Then reset the transaction set back
** to an empty set in preparation for a new round of acttab_action() calls.
**
** Return the offset into the action table of the new transaction.
*/
int acttab_insert(acttab *p){
  int i, j, k, n;
  int nActtab;     /* Number of slots in the p->aAction[] table */
  assert( p->nLookahead>0 );

  /* Make sure we have enough space to hold the expanded action table
  ** in the worst case.  The worst case occurs if the transaction set
  ** must be appended to the current action table
  */
  n = p->mxLookahead + 1;
  nActtab = p->nAction + n;
  if( nActtab >= p->nActionAlloc ){
    int oldAlloc = p->nActionAlloc;
    p->nActionAlloc = p->nAction + n + p->nActionAlloc + 20;
    p->aAction = realloc( p->aAction,
                          sizeof(p->aAction[0])*p->nActionAlloc);
    if( p->aAction==0 ){
      fprintf(stderr,"malloc failed\n");
      exit(1);
    }
    for(i=oldAlloc; i<p->nActionAlloc; i++){
      p->aAction[i].lookahead = -1;
      p->aAction[i].action = -1;
    }
  }

  /* Scan the existing action table looking for an offset where we can
  ** insert the current transaction set.  Fall out of the loop when that
  ** offset is found.  In the worst case, we fall out of the loop when
  ** i reaches nActtab, which means we append the new transaction set.
  **
  ** i is the index in p->aAction[] where p->mnLookahead is inserted.
  */
  for(i=nActtab-1; i>=0; i--){
    /* First look for an existing action table entry that can be reused */
    if( p->aAction[i].lookahead==p->mnLookahead ){
      if( p->aAction[i].action!=p->mnAction ) continue;
      for(j=0; j<p->nLookahead; j++){
        k = p->aLookahead[j].lookahead - p->mnLookahead + i;
        if( k<0 || k>=p->nAction ) break;
        if( p->aLookahead[j].lookahead!=p->aAction[k].lookahead ) break;

      if( n==p->nLookahead ){
        break;  /* Same as a prior transaction set */
      }
    }
  }
  if( i<0 ){
    /* If no reusable entry is found, look for an empty slot */
    for(i=0; i<nActtab; i++){
      if( p->aAction[i].lookahead<0 ){
        for(j=0; j<p->nLookahead; j++){
          k = p->aLookahead[j].lookahead - p->mnLookahead + i;
          if( k<0 ) break;
          if( p->aAction[k].lookahead>=0 ) break;
        }
        if( j<p->nLookahead ) continue;