@Override
public boolean checkPreconditions(ParseConfiguration configuration) {
if (configuration.getStack().isEmpty()) {
if (LOG.isTraceEnabled()) {
LOG.trace("Cannot apply " + this.toString() + ": stack is empty");
}
return false;
}
// top of stack must already have a governor
PosTaggedToken topOfStack = configuration.getStack().peek();
PosTaggedToken governor = configuration.getHead(topOfStack);
if (governor == null) {
if (LOG.isTraceEnabled()) {
LOG.trace(
"Cannot apply "
+ this.toString()
+ ": top of stack "
+ topOfStack
+ " doesn't yet have a governor.");
}
return false;
}
return true;
}
@Override
protected void applyInternal(ParseConfiguration configuration) {
configuration.getStack().pop();
}
