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package org.zwobble.couscous.util;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.PeekingIterator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import static org.zwobble.couscous.util.ExtraLists.list;
public class ExtraIterables {
private ExtraIterables() {}
public static <T, U> void forEach(Iterable<? extends T> first, Iterable<? extends U> second, Action2<T, U> action) {
Iterator<? extends T> firstIterator = first.iterator();
Iterator<? extends U> secondIterator = second.iterator();
while (firstIterator.hasNext()) {
action.run(firstIterator.next(), secondIterator.next());
}
if (secondIterator.hasNext()) {
throw new RuntimeException("Iterables not of same length");
}
}
public static <T1, T2, R> Iterable<R> lazyMap(Iterable<T1> iterable1, Iterable<T2> iterable2, BiFunction<T1, T2, R> function) {
return new Iterable<R>() {
@Override
public Iterator<R> iterator() {
Iterator<T1> iterator1 = iterable1.iterator();
Iterator<T2> iterator2 = iterable2.iterator();
return map(iterator1, iterator2, function);
}
};
}
private static <R, T1, T2> Iterator<R> map(Iterator<T1> iterator1, Iterator<T2> iterator2, BiFunction<T1, T2, R> function) {
return new Iterator<R>() {
@Override
public boolean hasNext() {
return iterator1.hasNext() && iterator2.hasNext();
}
@Override
public R next() {
return function.apply(iterator1.next(), iterator2.next());
}
};
}
public static <T> Iterable<T> cast(Class<T> type, Iterable<?> iterable) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return cast(type, iterable.iterator());
}
};
}
private static <T> Iterator<T> cast(Class<T> type, Iterator<?> iterator) {
return new Iterator<T>() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public T next() {
Object next = iterator.next();
if (type.isInstance(next)) {
return (T) next;
} else {
throw new ClassCastException();
}
}
};
}
public static <T> Iterable<T> lazyAppend(Iterable<T> head, T tail) {
return Iterables.concat(head, list(tail));
}
public static <T> Iterable<T> lazyCons(T head, Iterable<? extends T> tails) {
return Iterables.concat(list(head), tails);
}
public static <T> Iterable<T> lazyFilter(Iterable<T> iterable, java.util.function.Predicate<T> predicate) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return stream(iterable).filter(predicate).iterator();
}
};
}
public static <T> Optional<T> find(Iterable<T> iterable, Predicate<T> predicate) {
for (T element : iterable) {
if (predicate.test(element)) {
return Optional.of(element);
}
}
return Optional.empty();
}
public static <T, R> Iterable<R> lazyMap(Iterable<? extends T> iterable, Function<T, R> function) {
return new Iterable<R>() {
@Override
public Iterator<R> iterator() {
return map(iterable.iterator(), function);
}
};
}
private static <T, R> Iterator<R> map(Iterator<? extends T> iterator, Function<T, R> function) {
return new Iterator<R>() {
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public R next() {
return function.apply(iterator.next());
}
};
}
public static <T, R> Iterable<R> lazyFlatMap(Iterable<T> iterable, Function<T, Iterable<R>> function) {
return iterable(() -> stream(iterable).flatMap(element -> stream(function.apply(element))));
}
public static <T> Stream<T> stream(Iterable<T> iterable) {
return StreamSupport.stream(iterable.spliterator(), false);
}
public static <T, E> Iterable<T> iterable(Supplier<Stream<T>> stream) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return stream.get().iterator();
}
};
}
public static <T> Iterable<T> empty() {
return ImmutableList.of();
}
public static <T> Iterable<T> of(T e1) {
return ImmutableList.of(e1);
}
public static <T> Iterable<T> of(T e1, T e2) {
return ImmutableList.of(e1, e2);
}
public static <T> Iterable<T> of(T e1, T e2, T e3) {
return ImmutableList.of(e1, e2, e3);
}
public static <T> Iterable<T> iterable(Optional<T> optional) {
if (optional.isPresent()) {
return of(optional.get());
} else {
return empty();
}
}
public static <T> Iterable<T> takeUntil(Iterable<T> iterable, Predicate<T> predicate) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return takeUntil(iterable.iterator(), predicate);
}
};
}
public static <T> Iterator<T> takeUntil(Iterator<T> iterator, Predicate<T> predicate) {
PeekingIterator<T> peekingIterator = Iterators.peekingIterator(iterator);
return new Iterator<T>() {
@Override
public boolean hasNext() {
return peekingIterator.hasNext() && !predicate.test(peekingIterator.peek());
}
@Override
public T next() {
if (hasNext()) {
return peekingIterator.next();
} else {
throw new NoSuchElementException();
}
}
};
}
}
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