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package org.zwobble.mammoth.internal.util;
import java.util.Iterator;
import java.util.Optional;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
public class Iterables {
public static <T> Optional<T> tryFind(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<T> iterable, Function<T, R> function) {
return new Iterable<R>() {
@Override
public Iterator<R> iterator() {
return map(iterable.iterator(), function);
}
};
}
public static <T, R> Iterable<R> lazyMapWithIndex(Iterable<T> iterable, BiFunction<Integer, T, R> function) {
return new Iterable<R>() {
@Override
public Iterator<R> iterator() {
return map(iterable.iterator(), function);
}
};
}
public static <T> Optional<T> getFirst(Iterable<? extends T> iterable) {
Iterator<? extends T> iterator = iterable.iterator();
if (iterator.hasNext()) {
return Optional.of(iterator.next());
} else {
return Optional.empty();
}
}
public static <T> T getFirst(Iterable<? extends T> iterable, T defaultValue) {
Iterator<? extends T> iterator = iterable.iterator();
if (iterator.hasNext()) {
return iterator.next();
} else {
return defaultValue;
}
}
public static <T, R> Iterable<R> lazyFlatMap(Iterable<T> iterable, Function<T, Iterable<R>> function) {
return lazyFlatten(lazyMap(iterable, function));
}
public static <T> Iterable<T> lazyConcat(Iterable<T> iterable1, Iterable<T> iterable2) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return Stream.concat(stream(iterable1), stream(iterable2)).iterator();
}
};
}
public static <T> Iterable<T> lazyFlatten(Iterable<? extends Iterable<T>> iterables) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return stream(iterables)
.flatMap(iterable -> stream(iterable))
.iterator();
}
};
}
public static <T> Iterable<T> lazyFilter(Iterable<T> iterables, Predicate<T> predicate) {
return new Iterable<T>() {
@Override
public Iterator<T> iterator() {
return stream(iterables)
.filter(predicate)
.iterator();
}
};
}
public static <T, R> Iterable<R> lazyFilter(Iterable<T> iterables, Class<R> clazz) {
return new Iterable<R>() {
@Override
@SuppressWarnings("unchecked")
public Iterator<R> iterator() {
return (Iterator<R>) stream(iterables)
.filter(clazz::isInstance)
.iterator();
}
};
}
private static <T, R> Iterator<R> map(Iterator<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());
}
};
}
private static <T, R> Iterator<R> map(Iterator<T> iterator, BiFunction<Integer, T, R> function) {
return new Iterator<R>() {
private int nextIndex = 0;
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public R next() {
return function.apply(nextIndex++, iterator.next());
}
};
}
public static <T> boolean any(Iterable<T> iterable, Predicate<T> predicate) {
return stream(iterable).anyMatch(predicate);
}
public static <T> Stream<T> stream(Iterable<T> iterable) {
return StreamSupport.stream(iterable.spliterator(), false);
}
}
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