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Library providing immutable/persistent collection classes for
Java. While collections are immutable they provide methods for
adding and removing values by creating new modified copies of
themselves. Each copy shares almost all of its structure with
other copies to minimize memory consumption.
///###////////////////////////////////////////////////////////////////////////
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// Burton Computer Corporation
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//
// Copyright (c) 2017, Burton Computer Corporation
// All rights reserved.
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package org.javimmutable.collections.iterators;
import org.javimmutable.collections.Indexed;
import org.javimmutable.collections.SplitIterator;
import org.javimmutable.collections.SplitableIterable;
import org.javimmutable.collections.SplitableIterator;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.NoSuchElementException;
import java.util.function.Function;
public class LazyMultiIterator
extends AbstractSplitableIterator
{
@Nonnull
private final SplitableIterator> source;
@Nullable
private SplitableIterator iterator;
private boolean advanced;
private boolean hasNext;
private T nextValue;
private LazyMultiIterator(@Nonnull SplitableIterator> source,
@Nullable SplitableIterator iterator,
boolean advanced,
boolean hasNext,
T nextValue)
{
this.source = source;
this.iterator = iterator;
this.advanced = advanced;
this.hasNext = hasNext;
this.nextValue = nextValue;
}
@Nonnull
public static LazyMultiIterator iterator(@Nonnull Indexed> source)
{
return iterator(IndexedIterator.iterator(source));
}
@Nonnull
public static LazyMultiIterator iterator(@Nonnull SplitableIterator> source)
{
return new LazyMultiIterator<>(source, null, false, false, null);
}
/**
* Constructs an iterator that visits all of the values reachable from all of the
* SplitableIterables visited by source. All values are transformed using the provided method.
*/
public static LazyMultiIterator transformed(SplitableIterator source,
Function> transforminator)
{
return iterator(TransformIterator.of(source, transforminator));
}
/**
* Constructs an iterator that visits all of the values reachable from all of the
* SplitableIterables visited by source. All values are transformed using the provided method.
*/
public static LazyMultiIterator transformed(Indexed source,
Function> transforminator)
{
return iterator(TransformIterator.of(IndexedIterator.iterator(source), transforminator));
}
@Override
public boolean hasNext()
{
advance();
return hasNext;
}
@Override
public T next()
{
advance();
if (!hasNext) {
throw new NoSuchElementException();
}
advanced = false;
return nextValue;
}
@Override
public boolean isSplitAllowed()
{
return source.isSplitAllowed();
}
@Nonnull
@Override
public SplitIterator splitIterator()
{
final SplitIterator> split = source.splitIterator();
return new SplitIterator<>(new LazyMultiIterator<>(split.getLeft(), iterator, advanced, hasNext, nextValue),
new LazyMultiIterator<>(split.getRight(), null, false, false, null));
}
private void advance()
{
if (!advanced) {
advanceImpl();
advanced = true;
}
}
private void advanceImpl()
{
if (iterator != null) {
if (iterator.hasNext()) {
hasNext = true;
nextValue = iterator.next();
return;
}
}
assert (iterator == null) || !iterator.hasNext();
while (source.hasNext()) {
final SplitableIterable nextIterable = source.next();
final SplitableIterator nextIterator = nextIterable.iterator();
if (nextIterator.hasNext()) {
iterator = nextIterator;
hasNext = true;
nextValue = iterator.next();
return;
}
}
hasNext = false;
}
}