internal virtual Tree GetStackNode(int depth)
{
if (depth >= stack.Size())
{
return(null);
}
TreeShapedStack <Tree> node = stack;
for (int i = 0; i < depth; ++i)
{
node = node.Pop();
}
return(node.Peek());
}
public static CoreLabel GetStackLabel(TreeShapedStack <Tree> stack, int nodeNum, params FeatureFactory.Transition[] transitions)
{
if (stack.Size() <= nodeNum)
{
return(null);
}
for (int i = 0; i < nodeNum; ++i)
{
stack = stack.Pop();
}
Tree node = stack.Peek();
// TODO: this is nice for code readability, but might be expensive
foreach (FeatureFactory.Transition t in transitions)
{
switch (t)
{
case FeatureFactory.Transition.Left:
{
if (node.Children().Length != 2)
{
return(null);
}
node = node.Children()[0];
break;
}
case FeatureFactory.Transition.Right:
{
if (node.Children().Length != 2)
{
return(null);
}
node = node.Children()[1];
break;
}
case FeatureFactory.Transition.Unary:
{
if (node.Children().Length != 1)
{
return(null);
}
node = node.Children()[0];
break;
}
default:
{
throw new ArgumentException("Unknown transition type " + t);
}
}
}
if (!(node.Label() is CoreLabel))
{
throw new ArgumentException("Can only featurize CoreLabel trees");
}
return((CoreLabel)node.Label());
}
public static CoreLabel GetRecentDependent(TreeShapedStack <Tree> stack, FeatureFactory.Transition transition, int nodeNum)
{
if (stack.Size() <= nodeNum)
{
return(null);
}
for (int i = 0; i < nodeNum; ++i)
{
stack = stack.Pop();
}
Tree node = stack.Peek();
if (node == null)
{
return(null);
}
if (!(node.Label() is CoreLabel))
{
throw new ArgumentException("Can only featurize CoreLabel trees");
}
CoreLabel head = ((CoreLabel)node.Label()).Get(typeof(TreeCoreAnnotations.HeadWordLabelAnnotation));
switch (transition)
{
case FeatureFactory.Transition.Left:
{
while (true)
{
if (node.Children().Length == 0)
{
return(null);
}
Tree child = node.Children()[0];
if (!(child.Label() is CoreLabel))
{
throw new ArgumentException("Can only featurize CoreLabel trees");
}
if (((CoreLabel)child.Label()).Get(typeof(TreeCoreAnnotations.HeadWordLabelAnnotation)) != head)
{
return((CoreLabel)child.Label());
}
node = child;
}
goto case FeatureFactory.Transition.Right;
}
case FeatureFactory.Transition.Right:
{
while (true)
{
if (node.Children().Length == 0)
{
return(null);
}
if (node.Children().Length == 1)
{
node = node.Children()[0];
continue;
}
Tree child = node.Children()[1];
if (!(child.Label() is CoreLabel))
{
throw new ArgumentException("Can only featurize CoreLabel trees");
}
if (((CoreLabel)child.Label()).Get(typeof(TreeCoreAnnotations.HeadWordLabelAnnotation)) != head)
{
return((CoreLabel)child.Label());
}
node = child;
}
goto default;
}
default:
{
throw new ArgumentException("Can only get left or right heads");
}
}
}