public ContainerEntry NearestIndexedContainer(long position)
{
// We want the first container which ends after the position and starts before it.
// All containers ending before position can't contain it.
// Find the first container ending after position.
int indexAfter = IndexOfFirstEndingAfter(position);
// If position was after the last container end, return empty
if (indexAfter >= _index.Count)
{
return(ContainerEntry.Empty);
}
// Find the first ancestor of the container which starts before position
ContainerEntry candidate = this[indexAfter];
while (candidate.StartByteOffset > position)
{
candidate = Parent(candidate);
}
// Since all ancestors of indexed containers are indexed, this must be the closest indexed ancestor.
return(candidate);
}
public void Skip()
{
// If this container is indexed, skip by seeking
if (_containerIndex != null)
{
ContainerEntry entry = _containerIndex.NearestIndexedContainer(BytesRead);
if (entry.StartByteOffset == BytesRead)
{
_reader.Seek(entry.EndByteOffset, SeekOrigin.Begin);
return;
}
}
// Record depth
long start = BytesRead;
int depth = _currentDepth;
// Read one token
Read();
// If it wasn't a container, we're done
if (depth == _currentDepth)
{
return;
}
SkipRest();
long lengthSkipped = BytesRead - start;
}
public ContainerEntry Parent(ContainerEntry entry)
{
if (entry.ParentIndex < 0 || entry.ParentIndex >= _index.Count)
{
return(ContainerEntry.Empty);
}
return(_index[entry.ParentIndex]);
}
public int Depth(ContainerEntry entry)
{
int depth = 0;
ContainerEntry ancestor = entry;
while (ancestor.Index != -1)
{
depth++;
ancestor = Parent(ancestor);
}
return(depth);
}
public void End(long containerEndOffset)
{
ContainerEntry entry = new ContainerEntry(_currentStack.Pop(), containerEndOffset, _index.Count);
int depth = _currentStack.Count;
// Index this container if it's long enough, it's far enough away from the last indexed container, or if we indexed a descendant of it
if (entry.ByteLength >= ContainerLengthCutoff ||
containerEndOffset - _lastIndexedEnd >= ContainerLengthCutoff ||
_mustIndexDepth == depth)
{
_index.Add(entry);
_lastIndexedEnd = containerEndOffset;
_mustIndexDepth = depth - 1;
}
}
public void Read(BionReader reader)
{
_index.Clear();
reader.Read(BionToken.StartArray);
// Read the Container Index
long lastEndPosition = 0;
while (reader.Read())
{
if (reader.TokenType != BionToken.Integer)
{
break;
}
long endPosition = lastEndPosition + reader.CurrentInteger();
reader.Read(BionToken.Integer);
long byteLength = reader.CurrentInteger();
_index.Add(new ContainerEntry(endPosition - byteLength, endPosition, _index.Count));
lastEndPosition = endPosition;
}
// Reconstruct the hierarchy
for (int i = _index.Count - 2; i >= 0; --i)
{
ContainerEntry current = _index[i];
// Find the parent - the first container which starts before this one
int parentIndex = i + 1;
while (parentIndex != -1)
{
if (_index[parentIndex].StartByteOffset < current.StartByteOffset)
{
current.ParentIndex = parentIndex;
_index[i] = current;
break;
}
parentIndex = _index[parentIndex].ParentIndex;
}
}
// Size exact
_index.Capacity = _index.Count;
}
public ContainerEntry AncestorAtDepth(ContainerEntry entry, int depth)
{
int entryDepth = Depth(entry);
if (entryDepth < depth)
{
return(ContainerEntry.Empty);
}
int currentDepth = entryDepth;
ContainerEntry ancestor = entry;
while (currentDepth != depth)
{
ancestor = Parent(ancestor);
currentDepth--;
}
return(ancestor);
}
