public bool MoveNext()
{
AssertNoChanges();
while (_currentPage != null)
{
_currentPage.LastSearchPosition++;
if (_currentPage.LastSearchPosition < _currentPage.NumberOfEntries)
{
// run out of entries, need to select the next page...
while (_currentPage.IsBranch)
{
_parent._cursor.Push(_currentPage);
var childParentNumber = _currentPage.GetEntry(_currentPage.LastSearchPosition)->PageNumber;
_currentPage = _parent.GetReadOnlyPage(childParentNumber);
_currentPage.LastSearchPosition = 0;
}
return(true);// there is another entry in this page
}
if (_parent._cursor.Count == 0)
{
break;
}
_currentPage = _parent._cursor.Pop();
}
_currentPage = null;
return(false);
}
public bool MovePrev()
{
AssertNoChanges();
if (_currentPage == null)
{
throw new InvalidOperationException("No current page was set");
}
while (_currentPage != null)
{
_currentPage.LastSearchPosition--;
if (_currentPage.LastSearchPosition >= 0)
{
// run out of entries, need to select the next page...
while (_currentPage.IsBranch)
{
_parent._cursor.Push(_currentPage);
var childParentNumber = _currentPage.GetEntry(_currentPage.LastSearchPosition)->PageNumber;
_currentPage = _parent.GetReadOnlyPage(childParentNumber);
_currentPage.LastSearchPosition = _currentPage.NumberOfEntries - 1;
}
return(true);// there is another entry in this page
}
if (_parent._cursor.Count == 0)
{
break;
}
_currentPage = _parent._cursor.Pop();
}
_currentPage = null;
return(false);
}
public bool MoveNext()
{
AssertNoChanges();
if (_currentPage == null)
{
throw new InvalidOperationException("No current page was set");
}
while (_currentPage != null)
{
_currentPage.LastSearchPosition++;
if (_currentPage.LastSearchPosition < _currentPage.NumberOfEntries)
{
// run out of entries, need to select the next page...
while (_currentPage.IsBranch)
{
_parent._cursor.Push(_currentPage);
var childParentNumber = _parent.PageValueFor(_currentPage, _currentPage.LastSearchPosition);
_currentPage = _parent._tx.GetReadOnlyFixedSizeTreePage(childParentNumber);
_currentPage.LastSearchPosition = 0;
}
return(true);// there is another entry in this page
}
if (_parent._cursor.Count == 0)
{
break;
}
_currentPage = _parent._cursor.Pop();
}
_currentPage = null;
return(false);
}
public bool Skip(long count)
{
if (count > 0)
{
if (MoveNext(count) == false)
{
return(false);
}
}
else
{
if (MovePrev(-count) == false)
{
return(false);
}
}
var seek = _currentPage != null && _currentPage.LastSearchPosition != _currentPage.NumberOfEntries;
if (seek == false)
{
_currentPage = null;
}
return(seek);
}
private bool MovePrev(long skip)
{
AssertNoChanges();
if (_currentPage == null || _currentPage.IsLeaf == false)
{
throw new InvalidOperationException("No current page was set or is wasn't a leaf!");
}
while (skip >= 0)
{
var skipInPage = (int)Math.Min(_currentPage.LastSearchPosition, skip);
skip -= skipInPage;
_currentPage.LastSearchPosition -= skipInPage;
if (skip == 0)
{
return(true);
}
while (true)
{
if (_parent._cursor.TryPeek(out var parent) == false)
{
return(false);
}
parent.LastSearchPosition--;
if (parent.LastSearchPosition < 0)
{
_parent._cursor.Pop();
continue;
}
var nextChildPageNumber = parent.GetEntry(parent.LastSearchPosition)->PageNumber;
var childPage = _parent.GetReadOnlyPage(nextChildPageNumber);
// we move one beyond the end of elements because in both cases
// (branch and leaf) we first decrement and then run it
childPage.LastSearchPosition = childPage.NumberOfEntries;
if (childPage.IsBranch)
{
_parent._cursor.Push(childPage);
continue;
}
_currentPage = childPage;
break;
}
}
_currentPage = null;
return(false);
}
public bool Skip(int count)
{
if (count != 0)
{
for (int i = 0; i < Math.Abs(count); i++)
{
if (!MoveNext())
{
break;
}
}
}
var seek = _currentPage != null && _currentPage.LastSearchPosition != _currentPage.NumberOfEntries;
if (seek == false)
{
_currentPage = null;
}
return(seek);
}
private bool MoveNext(long skip)
{
AssertNoChanges();
if (_currentPage == null || _currentPage.IsLeaf == false)
{
throw new InvalidOperationException("No current page was set or is wasn't a leaf!");
}
while (skip >= 0)
{
var skipInPage = (int)Math.Min(_currentPage.NumberOfEntries - _currentPage.LastSearchPosition, skip);
skip -= skipInPage;
_currentPage.LastSearchPosition += skipInPage;
if (skip == 0)
{
if (_currentPage.LastSearchPosition >= _currentPage.NumberOfEntries)
{
return(MoveNext());
}
return(true);
}
while (true)
{
if (_parent._cursor.TryPeek(out var parent) == false)
{
return(false);
}
parent.LastSearchPosition++;
if (parent.LastSearchPosition >= parent.NumberOfEntries)
{
_parent._cursor.Pop();
continue;
}
var nextChildPageNumber = parent.GetEntry(parent.LastSearchPosition)->PageNumber;
var childPage = _parent.GetReadOnlyPage(nextChildPageNumber);
if (childPage.IsBranch)
{
// we set it to negative one so the first
// call will increment that to zero
childPage.LastSearchPosition = -1;
_parent._cursor.Push(childPage);
continue;
}
else
{
childPage.LastSearchPosition = 0;
}
_currentPage = childPage;
break;
}
}
_currentPage = null;
return(false);
}
public bool SeekToLast()
{
_currentPage = _parent.FindPageFor(long.MaxValue);
return(true);
}
public bool Seek(long key)
{
_currentPage = _parent.FindPageFor(key);
return(_currentPage.LastMatch <= 0 || MoveNext());
}