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package bjc.utils.data;
import static bjc.utils.data.TopDownTransformResult.RTRANSFORM;
import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.NoSuchElementException;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
/*
* @TODO 10/11/17 Ben Culkin :TopDownStep
*
* Figure out what is broken with this, and fix it so that step-wise
* iteration works correctly.
*/
public class TopDownTransformIterator<ContainedType> implements Iterator<ITree<ContainedType>> {
private final Function<ContainedType, TopDownTransformResult> picker;
private final BiFunction<ITree<ContainedType>, Consumer<Iterator<ITree<ContainedType>>>, ITree<ContainedType>> transform;
private ITree<ContainedType> preParent;
private ITree<ContainedType> postParent;
private final Deque<ITree<ContainedType>> preChildren;
private final Deque<ITree<ContainedType>> postChildren;
private TopDownTransformIterator<ContainedType> curChild;
private boolean done;
private boolean initial;
private final Deque<Iterator<ITree<ContainedType>>> toYield;
private Iterator<ITree<ContainedType>> curYield;
public TopDownTransformIterator(final Function<ContainedType, TopDownTransformResult> pickr,
final BiFunction<ITree<ContainedType>, Consumer<Iterator<ITree<ContainedType>>>, ITree<ContainedType>> transfrm,
final ITree<ContainedType> tree) {
preParent = tree;
preChildren = new LinkedList<>();
postChildren = new LinkedList<>();
toYield = new LinkedList<>();
picker = pickr;
transform = transfrm;
done = false;
initial = true;
}
public void addYield(final Iterator<ITree<ContainedType>> src) {
if(curYield != null) {
toYield.push(curYield);
}
curYield = src;
}
@Override
public boolean hasNext() {
return !done;
}
public ITree<ContainedType> flushYields(final ITree<ContainedType> val) {
if(curYield != null) {
toYield.add(new SingleIterator<>(val));
if(curYield.hasNext())
return curYield.next();
else {
while(toYield.size() != 0 && !curYield.hasNext()) {
curYield = toYield.pop();
}
if(toYield.size() == 0 && !curYield.hasNext()) {
curYield = null;
return val;
} else
return curYield.next();
}
} else
return val;
}
@Override
public ITree<ContainedType> next() {
if(done) throw new NoSuchElementException();
if(curYield != null) {
if(curYield.hasNext())
return curYield.next();
else {
while(toYield.size() != 0 && !curYield.hasNext()) {
curYield = toYield.pop();
}
if(toYield.size() == 0 && !curYield.hasNext()) {
curYield = null;
} else
return curYield.next();
}
}
if(initial) {
final TopDownTransformResult res = picker.apply(preParent.getHead());
switch(res) {
case PASSTHROUGH:
postParent = new Tree<>(preParent.getHead());
if(preParent.getChildrenCount() != 0) {
for(int i = 0; i < preParent.getChildrenCount(); i++) {
preChildren.add(preParent.getChild(i));
}
// Return whatever the first child is
break;
} else {
done = true;
return flushYields(postParent);
}
case SKIP:
done = true;
return flushYields(preParent);
case TRANSFORM:
done = true;
return flushYields(transform.apply(preParent, this::addYield));
case RTRANSFORM:
preParent = transform.apply(preParent, this::addYield);
return flushYields(preParent);
case PUSHDOWN:
if(preParent.getChildrenCount() != 0) {
for(int i = 0; i < preParent.getChildrenCount(); i++) {
preChildren.add(preParent.getChild(i));
}
// Return whatever the first child is
break;
} else {
done = true;
return flushYields(transform.apply(new Tree<>(preParent.getHead()),
this::addYield));
}
case PULLUP:
final ITree<ContainedType> intRes = transform.apply(preParent, this::addYield);
postParent = new Tree<>(intRes.getHead());
if(intRes.getChildrenCount() != 0) {
for(int i = 0; i < intRes.getChildrenCount(); i++) {
preChildren.add(intRes.getChild(i));
}
// Return whatever the first child is
break;
} else {
done = true;
return flushYields(postParent);
}
default:
throw new IllegalArgumentException("Unknown result type " + res);
}
if(res != RTRANSFORM) {
initial = false;
}
}
if(curChild == null || !curChild.hasNext()) {
if(preChildren.size() != 0) {
curChild = new TopDownTransformIterator<>(picker, transform, preChildren.pop());
final ITree<ContainedType> res = curChild.next();
System.out.println("\t\tTRACE: adding node " + res + " to children");
postChildren.add(res);
return flushYields(res);
} else {
ITree<ContainedType> res = null;
if(postParent == null) {
res = new Tree<>(preParent.getHead());
System.out.println("\t\tTRACE: adding nodes " + postChildren + " to " + res);
for(final ITree<ContainedType> child : postChildren) {
res.addChild(child);
}
// res = transform.apply(res,
// this::addYield);
} else {
res = postParent;
System.out.println("\t\tTRACE: adding nodes " + postChildren + " to " + res);
for(final ITree<ContainedType> child : postChildren) {
res.addChild(child);
}
}
done = true;
return flushYields(res);
}
} else {
final ITree<ContainedType> res = curChild.next();
System.out.println("\t\tTRACE: adding node " + res + " to children");
postChildren.add(res);
return flushYields(res);
}
}
}
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