void c4_FormatB::Remove(int index_, int count_) {
  _recalc = true;

  t4_i32 off = Offset(index_);
  t4_i32 n = Offset(index_ + count_) - off;
  d4_assert(n >= 0);

  // remove the columns, if present
  for (int i = 0; i < count_; ++i)
    delete (c4_Column*)_memos.GetAt(index_ + i);
  _memos.RemoveAt(index_, count_);

  if (n > 0)
    _data.Shrink(off, n);

  _offsets.RemoveAt(index_, count_);

  d4_assert(index_ < _offsets.GetSize());

  // adjust all following entries
  while (index_ < _offsets.GetSize())
    _offsets.ElementAt(index_++) -= n;

  d4_assert((t4_i32)_offsets.GetAt(index_ - 1) == _data.ColSize());
  d4_assert(index_ <= _memos.GetSize() + 1);
}

void c4_FormatB::InitOffsets(c4_ColOfInts& sizes_)
{
  int rows = Owner().NumRows();

  if (sizes_.RowCount() != rows) {
    sizes_.SetRowCount(rows);
  }

  _memos.SetSize(rows);
  _offsets.SetSize(rows + 1);

  if (_data.ColSize() > 0) {
    t4_i32 total = 0;

    for (int r = 0; r < rows; ++r) {
      int n = sizes_.GetInt(r);
      d4_assert(n >= 0);
      total += n;
      _offsets.SetAt(r + 1, total);
    }

    d4_assert(total == _data.ColSize());
  }
  
}

bool c4_JoinViewer::GetItem(int row_, int col_, c4_Bytes& buf_)
{
  c4_View v = _parent;

  int o = 0;
  int r = _offset.GetAt(row_);

  if (r < 0)
  {
    o = ~r;
    if (o == 0)
      return false; // if this is a null row in an outer join
    r -= o;
  }

  if (col_ >= v.NumProperties())
  {
    v = _argView;
    r = _o;

    col_ = v.FindProperty(_template.NthProperty(col_));
    if (col_ < 0)
      return false; // if second view doesn't have all properties
  }

  return v.GetItem(r, col_, buf_);
}

bool c4_GroupByViewer::GetItem(int row_, int col_, c4_Bytes& buf_)
{
  if (col_ < _keys.NumProperties())
    return _sorted.GetItem(_map.GetAt(row_), col_, buf_);

  d4_assert(col_ == _keys.NumProperties());
  
  t4_i32 count;
  switch (_result.Type())
  {
    case 'I': count = _map.GetAt(row_ + 1) - _map.GetAt(row_);
          buf_ = c4_Bytes (&count, sizeof count, true);
          break;
    case 'V': _temp = _sorted.Slice(_map.GetAt(row_), _map.GetAt(row_ + 1))
                .ProjectWithout(_keys);
          buf_ = c4_Bytes (&_temp, sizeof _temp, true);
          break;
    default:  d4_assert(0);
  }

  return true;
}

bool c4_JoinPropViewer::GetItem(int row_, int col_, c4_Bytes &buf_) {
  c4_View v = _parent;
  int r = _base.GetAt(row_);

  if (col_ >= _subPos)
  if (col_ >= _subPos + _subWidth) {
    col_ -= _subWidth - 1;
  } else {
    v = _sub(_parent[r]);
    r = _offset.GetAt(row_);
    if (r < 0)
      return false;
    // if this is a null row in an outer join

    col_ = v.FindProperty(_template.NthProperty(col_).GetId());
    if (col_ < 0)
      return false;
    // if subview doesn't have all properties
  }

  return v.GetItem(r, col_, buf_);
}

void c4_FormatB::Insert(int index_, const c4_Bytes& buf_, int count_)
{
  d4_assert(count_ > 0);

  _recalc = true;

  int m = buf_.Size();
  t4_i32 off = Offset(index_);

  _memos.InsertAt(index_, 0, count_);

    // insert the appropriate number of bytes
  t4_i32 n = count_ * (t4_i32) m;
  if (n > 0) {
    _data.Grow(off, n);

      // store as many copies as needed, but may have to do it in chunks
    int spos = 0;

    c4_ColIter iter (_data, off, off + n);
    while (iter.Next(m - spos)) {
      memcpy(iter.BufSave(), buf_.Contents() + spos, iter.BufLen());

      spos += iter.BufLen();
      if (spos >= m)
        spos = 0;
    }

    d4_assert(spos == 0); // must have copied an exact multiple of the data
  }

    // define offsets of the new entries
  _offsets.InsertAt(index_, 0, count_);
  d4_assert(_offsets.GetSize() <= _memos.GetSize() + 1);

  while (--count_ >= 0) {
    _offsets.SetAt(index_++, off);
    off += m;
  }

  d4_assert(index_ < _offsets.GetSize());

    // adjust all following entries
  while (index_ < _offsets.GetSize())
    _offsets.ElementAt(index_++) += n;

  d4_assert((t4_i32) _offsets.GetAt(index_ - 1) == _data.ColSize());
  d4_assert(index_ <= _memos.GetSize() + 1);
}

void c4_FormatB::SetOne(int index_, const c4_Bytes &xbuf_, bool ignoreMemos_) {
  // this fixes bug in 2.4.0 when copying string from higher row
  // TODO: this fix is very conservative, figure out when to copy
  // (can probably look at pointer to see whether it's from us)
  int sz = xbuf_.Size();
  c4_Bytes buf_(xbuf_.Contents(), sz, 0 < sz && sz <= c4_Column::kSegMax);

  c4_Column *cp = &_data;
  t4_i32 start = Offset(index_);
  int len = Offset(index_ + 1) - start;

  if (!ignoreMemos_ && _memos.GetAt(index_) != 0)
    len = ItemLenOffCol(index_, start, cp);

  int m = buf_.Size();
  int n = m - len;

  if (n > 0)
    cp->Grow(start, n);
  else if (n < 0)
    cp->Shrink(start,  - n);
  else if (m == 0)
    return ;
  // no size change and no contents

  _recalc = true;

  cp->StoreBytes(start, buf_);

  if (n && cp ==  &_data) {
    // if size has changed
    int k = _offsets.GetSize() - 1;

    // if filling in an empty entry at end: extend offsets first
    if (m > 0 && index_ >= k) {
      _offsets.InsertAt(k, _offsets.GetAt(k), index_ - k + 1);

      k = index_ + 1;
      d4_assert(k == _offsets.GetSize() - 1);
    }

    // adjust following entry offsets
    while (++index_ <= k)
      _offsets.ElementAt(index_) += n;
  }

  d4_assert((t4_i32)_offsets.GetAt(_offsets.GetSize() - 1) == _data.ColSize());
}

d4_inline t4_i32 c4_FormatB::Offset(int index_)const {
  d4_assert((t4_i32)_offsets.GetAt(_offsets.GetSize() - 1) == _data.ColSize());
  d4_assert(_offsets.GetSize() == _memos.GetSize() + 1);
  d4_assert(index_ < _offsets.GetSize());

  // extend offset vectors for missing empty entries at end 
  int n = _offsets.GetSize();
  d4_assert(n > 0);

  if (index_ >= n)
    index_ = n - 1;

  return _offsets.GetAt(index_);
}