/// <summary>
/// Rewind the current state of the tree walk to the state it
/// was in when Mark() was called and it returned marker. Also,
/// wipe out the lookahead which will force reloading a few nodes
/// but it is better than making a copy of the lookahead buffer
/// upon Mark().
/// </summary>
public virtual void Rewind(int marker)
{
if (markers == null)
{
return;
}
TreeWalkState state = (TreeWalkState)markers[marker];
absoluteNodeIndex = state.absoluteNodeIndex;
currentChildIndex = state.currentChildIndex;
currentNode = state.currentNode;
previousNode = state.previousNode;
// drop node and index stacks back to old size
nodeStack.Capacity = state.nodeStackSize;
indexStack.Capacity = state.indexStackSize;
head = tail = 0; // wack lookahead buffer and then refill
for (; tail < state.lookahead.Length; tail++)
{
lookahead[tail] = state.lookahead[tail];
}
Release(marker);
}
/// <summary>
/// Record the current state of the tree walk which includes
/// the current node and stack state as well as the lookahead
/// buffer.
/// </summary>
public virtual int Mark()
{
if (markers == null)
{
markers = new ArrayList();
markers.Add(null); // depth 0 means no backtracking, leave blank
}
markDepth++;
TreeWalkState state = null;
if (markDepth >= markers.Count)
{
state = new TreeWalkState();
markers.Add(state);
}
else
{
state = (TreeWalkState)markers[markDepth];
}
state.absoluteNodeIndex = absoluteNodeIndex;
state.currentChildIndex = currentChildIndex;
state.currentNode = currentNode;
state.previousNode = previousNode;
state.nodeStackSize = nodeStack.Count;
state.indexStackSize = indexStack.Count;
// take snapshot of lookahead buffer
int n = LookaheadSize;
int i = 0;
state.lookahead = new object[n];
for (int k = 1; k <= n; k++, i++)
{
state.lookahead[i] = LT(k);
}
lastMarker = markDepth;
return(markDepth);
}
/// <summary>
/// Record the current state of the tree walk which includes
/// the current node and stack state as well as the lookahead
/// buffer.
/// </summary>
public virtual int Mark()
{
if (markers == null)
{
markers = new ArrayList();
markers.Add(null); // depth 0 means no backtracking, leave blank
}
markDepth++;
TreeWalkState state = null;
if ( markDepth >= markers.Count )
{
state = new TreeWalkState();
markers.Add(state);
}
else
{
state = (TreeWalkState)markers[markDepth];
}
state.absoluteNodeIndex = absoluteNodeIndex;
state.currentChildIndex = currentChildIndex;
state.currentNode = currentNode;
state.previousNode = previousNode;
state.nodeStackSize = nodeStack.Count;
state.indexStackSize = indexStack.Count;
// take snapshot of lookahead buffer
int n = LookaheadSize;
int i = 0;
state.lookahead = new object[n];
for (int k = 1; k <= n; k++, i++)
{
state.lookahead[i] = LT(k);
}
lastMarker = markDepth;
return markDepth;
}
