/*
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package java.util.stream;
import static javaemul.internal.InternalPreconditions.checkNotNull;
import static javaemul.internal.InternalPreconditions.checkState;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Spliterators.AbstractDoubleSpliterator;
import java.util.Spliterators.AbstractIntSpliterator;
import java.util.Spliterators.AbstractLongSpliterator;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.BinaryOperator;
import java.util.function.Consumer;
import java.util.function.DoubleConsumer;
import java.util.function.Function;
import java.util.function.IntConsumer;
import java.util.function.IntFunction;
import java.util.function.LongConsumer;
import java.util.function.Predicate;
import java.util.function.Supplier;
import java.util.function.ToDoubleFunction;
import java.util.function.ToIntFunction;
import java.util.function.ToLongFunction;
/**
* Main implementation of Stream, wrapping a single spliterator and an optional parent stream.
*/
final class StreamImpl<T> extends TerminatableStream<StreamImpl<T>> implements Stream<T> {
/**
* Represents an empty stream, doing nothing for all methods.
*/
static class Empty<T> extends TerminatableStream<Empty<T>> implements Stream<T> {
public Empty(TerminatableStream<?> previous) {
super(previous);
}
@Override
public Stream<T> filter(Predicate<? super T> predicate) {
throwIfTerminated();
return this;
}
@Override
public <R> Stream<R> map(Function<? super T, ? extends R> mapper) {
throwIfTerminated();
return (Stream) this;
}
@Override
public IntStream mapToInt(ToIntFunction<? super T> mapper) {
throwIfTerminated();
return new IntStreamImpl.Empty(this);
}
@Override
public LongStream mapToLong(ToLongFunction<? super T> mapper) {
throwIfTerminated();
return new LongStreamImpl.Empty(this);
}
@Override
public DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper) {
throwIfTerminated();
return new DoubleStreamImpl.Empty(this);
}
@Override
public <R> Stream<R> flatMap(Function<? super T, ? extends Stream<? extends R>> mapper) {
throwIfTerminated();
return (Stream) this;
}
@Override
public IntStream flatMapToInt(Function<? super T, ? extends IntStream> mapper) {
throwIfTerminated();
return new IntStreamImpl.Empty(this);
}
@Override
public LongStream flatMapToLong(Function<? super T, ? extends LongStream> mapper) {
throwIfTerminated();
return new LongStreamImpl.Empty(this);
}
@Override
public DoubleStream flatMapToDouble(Function<? super T, ? extends DoubleStream> mapper) {
throwIfTerminated();
return new DoubleStreamImpl.Empty(this);
}
@Override
public Stream<T> distinct() {
throwIfTerminated();
return this;
}
@Override
public Stream<T> sorted() {
throwIfTerminated();
return this;
}
@Override
public Stream<T> sorted(Comparator<? super T> comparator) {
throwIfTerminated();
return this;
}
@Override
public Stream<T> peek(Consumer<? super T> action) {
throwIfTerminated();
return this;
}
@Override
public Stream<T> limit(long maxSize) {
throwIfTerminated();
checkState(maxSize >= 0, "maxSize may not be negative");
return this;
}
@Override
public Stream<T> skip(long n) {
throwIfTerminated();
checkState(n >= 0, "n may not be negative");
return this;
}
@Override
public void forEach(Consumer<? super T> action) {
terminate();
// nothing to do
}
@Override
public void forEachOrdered(Consumer<? super T> action) {
terminate();
// nothing to do
}
@Override
public Object[] toArray() {
terminate();
return new Object[0];
}
@Override
public <A> A[] toArray(IntFunction<A[]> generator) {
terminate();
return generator.apply(0);
}
@Override
public T reduce(T identity, BinaryOperator<T> accumulator) {
terminate();
return identity;
}
@Override
public Optional<T> reduce(BinaryOperator<T> accumulator) {
terminate();
return Optional.empty();
}
@Override
public <U> U reduce(
U identity, BiFunction<U, ? super T, U> accumulator, BinaryOperator<U> combiner) {
terminate();
return identity;
}
@Override
public <R> R collect(
Supplier<R> supplier, BiConsumer<R, ? super T> accumulator, BiConsumer<R, R> combiner) {
terminate();
return supplier.get();
}
@Override
public <R, A> R collect(Collector<? super T, A, R> collector) {
terminate();
return collector.finisher().apply(collector.supplier().get());
}
@Override
public Optional<T> min(Comparator<? super T> comparator) {
terminate();
return Optional.empty();
}
@Override
public Optional<T> max(Comparator<? super T> comparator) {
terminate();
return Optional.empty();
}
@Override
public long count() {
terminate();
return 0;
}
@Override
public boolean anyMatch(Predicate<? super T> predicate) {
terminate();
return false;
}
@Override
public boolean allMatch(Predicate<? super T> predicate) {
terminate();
return true;
}
@Override
public boolean noneMatch(Predicate<? super T> predicate) {
terminate();
return true;
}
@Override
public Optional<T> findFirst() {
terminate();
return Optional.empty();
}
@Override
public Optional<T> findAny() {
terminate();
return Optional.empty();
}
@Override
public Iterator<T> iterator() {
terminate();
return Collections.emptyIterator();
}
@Override
public Spliterator<T> spliterator() {
terminate();
return Spliterators.emptySpliterator();
}
@Override
public boolean isParallel() {
throwIfTerminated();
return false;
}
@Override
public Stream<T> sequential() {
throwIfTerminated();
return this;
}
@Override
public Stream<T> parallel() {
throwIfTerminated();
return this;
}
@Override
public Stream<T> unordered() {
throwIfTerminated();
return this;
}
}
/**
* Object to Object map spliterator.
*
* @param <U> the input type
* @param <T> the output type
*/
private static final class MapToObjSpliterator<U, T> extends Spliterators.AbstractSpliterator<T> {
private final Function<? super U, ? extends T> map;
private final Spliterator<U> original;
public MapToObjSpliterator(Function<? super U, ? extends T> map, Spliterator<U> original) {
super(
original.estimateSize(),
original.characteristics() & ~(Spliterator.SORTED | Spliterator.DISTINCT));
checkNotNull(map);
this.map = map;
this.original = original;
}
@Override
public boolean tryAdvance(final Consumer<? super T> action) {
return original.tryAdvance(u -> action.accept(map.apply(u)));
}
}
/**
* Object to Int map spliterator.
*
* @param <T> the input type
*/
private static final class MapToIntSpliterator<T> extends Spliterators.AbstractIntSpliterator {
private final ToIntFunction<? super T> map;
private final Spliterator<T> original;
public MapToIntSpliterator(ToIntFunction<? super T> map, Spliterator<T> original) {
super(
original.estimateSize(),
original.characteristics() & ~(Spliterator.SORTED | Spliterator.DISTINCT));
checkNotNull(map);
this.map = map;
this.original = original;
}
@Override
public boolean tryAdvance(final IntConsumer action) {
return original.tryAdvance(u -> action.accept(map.applyAsInt(u)));
}
}
/**
* Object to Long map spliterator.
*
* @param <T> the input type
*/
private static final class MapToLongSpliterator<T> extends Spliterators.AbstractLongSpliterator {
private final ToLongFunction<? super T> map;
private final Spliterator<T> original;
public MapToLongSpliterator(ToLongFunction<? super T> map, Spliterator<T> original) {
super(
original.estimateSize(),
original.characteristics() & ~(Spliterator.SORTED | Spliterator.DISTINCT));
checkNotNull(map);
this.map = map;
this.original = original;
}
@Override
public boolean tryAdvance(final LongConsumer action) {
return original.tryAdvance(u -> action.accept(map.applyAsLong(u)));
}
}
/**
* Object to Double map spliterator.
*
* @param <T> the input type
*/
private static final class MapToDoubleSpliterator<T>
extends Spliterators.AbstractDoubleSpliterator {
private final ToDoubleFunction<? super T> map;
private final Spliterator<T> original;
public MapToDoubleSpliterator(ToDoubleFunction<? super T> map, Spliterator<T> original) {
super(
original.estimateSize(),
original.characteristics() & ~(Spliterator.SORTED | Spliterator.DISTINCT));
checkNotNull(map);
this.map = map;
this.original = original;
}
@Override
public boolean tryAdvance(final DoubleConsumer action) {
return original.tryAdvance(u -> action.accept(map.applyAsDouble(u)));
}
}
/**
* Object filter spliterator.
*
* @param <T> the type of data to iterate over
*/
private static final class FilterSpliterator<T> extends Spliterators.AbstractSpliterator<T> {
private final Predicate<? super T> filter;
private final Spliterator<T> original;
private boolean found;
public FilterSpliterator(Predicate<? super T> filter, Spliterator<T> original) {
super(original.estimateSize(), original.characteristics() & ~Spliterator.SIZED);
checkNotNull(filter);
this.filter = filter;
this.original = original;
}
@Override
public Comparator<? super T> getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(final Consumer<? super T> action) {
found = false;
while (!found
&& original.tryAdvance(
item -> {
if (filter.test(item)) {
found = true;
action.accept(item);
}
})) {
// do nothing, work is done in tryAdvance
}
return found;
}
}
/**
* Object skip spliterator.
*
* @param <T> the type of data to iterate over
*/
private static final class SkipSpliterator<T> extends Spliterators.AbstractSpliterator<T> {
private long skip;
private final Spliterator<T> original;
public SkipSpliterator(long skip, Spliterator<T> original) {
super(
original.hasCharacteristics(Spliterator.SIZED)
? Math.max(0, original.estimateSize() - skip)
: Long.MAX_VALUE,
original.characteristics());
this.skip = skip;
this.original = original;
}
@Override
public Comparator<? super T> getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(Consumer<? super T> action) {
while (skip > 0) {
if (!original.tryAdvance(ignore -> { })) {
return false;
}
skip--;
}
return original.tryAdvance(action);
}
}
/**
* Object limit spliterator.
*
* @param <T> the type of data to iterate over
*/
private static final class LimitSpliterator<T> extends Spliterators.AbstractSpliterator<T> {
private final long limit;
private final Spliterator<T> original;
private int position = 0;
public LimitSpliterator(long limit, Spliterator<T> original) {
super(
original.hasCharacteristics(Spliterator.SIZED)
? Math.min(original.estimateSize(), limit)
: Long.MAX_VALUE,
original.characteristics());
this.limit = limit;
this.original = original;
}
@Override
public Comparator<? super T> getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(Consumer<? super T> action) {
if (position >= limit) {
return false;
}
boolean result = original.tryAdvance(action);
position++;
return result;
}
}
/**
* Value holder for various stream operations.
*/
private static final class ValueConsumer<T> implements Consumer<T> {
T value;
@Override
public void accept(T value) {
this.value = value;
}
}
private final Spliterator<T> spliterator;
public StreamImpl(TerminatableStream<?> prev, Spliterator<T> spliterator) {
super(prev);
this.spliterator = spliterator;
}
// terminal
@Override
public Spliterator<T> spliterator() {
terminate();
return spliterator;
}
@Override
public Iterator<T> iterator() {
return Spliterators.iterator(spliterator());
}
@Override
public long count() {
terminate();
long count = 0;
while (spliterator.tryAdvance(a -> { })) {
count++;
}
return count;
}
@Override
public void forEach(Consumer<? super T> action) {
forEachOrdered(action);
}
@Override
public void forEachOrdered(Consumer<? super T> action) {
terminate();
spliterator.forEachRemaining(action);
}
@Override
public Object[] toArray() {
return toArray(Object[]::new);
}
@Override
public <A> A[] toArray(IntFunction<A[]> generator) {
List<T> collected = collect(Collectors.toList());
return collected.toArray(generator.apply(collected.size()));
}
@Override
public <R> R collect(
Supplier<R> supplier, BiConsumer<R, ? super T> accumulator, BiConsumer<R, R> combiner) {
return collect(
Collector.of(
supplier,
accumulator,
(a, b) -> {
combiner.accept(a, b);
return a;
}));
}
@Override
public <R, A> R collect(final Collector<? super T, A, R> collector) {
return collector
.finisher()
.apply(
reduce(
collector.supplier().get(),
(a, t) -> {
collector.accumulator().accept(a, t);
return a;
},
collector.combiner()));
}
@Override
public Optional<T> findFirst() {
terminate();
ValueConsumer<T> holder = new ValueConsumer<T>();
if (spliterator.tryAdvance(holder)) {
return Optional.of(holder.value);
}
return Optional.empty();
}
@Override
public Optional<T> findAny() {
return findFirst();
}
private static final Consumer<Object> NULL_CONSUMER = value -> { };
@Override
public boolean anyMatch(Predicate<? super T> predicate) {
return filter(predicate).spliterator().tryAdvance(NULL_CONSUMER);
}
@Override
public boolean allMatch(final Predicate<? super T> predicate) {
return !anyMatch(predicate.negate());
}
@Override
public boolean noneMatch(final Predicate<? super T> predicate) {
return !anyMatch(predicate);
}
@Override
public Optional<T> min(final Comparator<? super T> comparator) {
return reduce(BinaryOperator.minBy(comparator));
}
@Override
public Optional<T> max(final Comparator<? super T> comparator) {
return reduce(BinaryOperator.maxBy(comparator));
}
@Override
public T reduce(T identity, BinaryOperator<T> accumulator) {
return reduce(identity, accumulator, accumulator);
}
@Override
public Optional<T> reduce(BinaryOperator<T> accumulator) {
ValueConsumer<T> consumer = new ValueConsumer<T>();
if (!spliterator.tryAdvance(consumer)) {
terminate();
return Optional.empty();
}
return Optional.of(reduce(consumer.value, accumulator));
}
// combiner is ignored, since we don't parallelize
@Override
public <U> U reduce(
U identity, BiFunction<U, ? super T, U> accumulator, BinaryOperator<U> combiner) {
terminate();
final ValueConsumer<U> consumer = new ValueConsumer<U>();
consumer.value = identity;
spliterator.forEachRemaining(
item -> {
consumer.accept(accumulator.apply(consumer.value, item));
});
return consumer.value;
}
// end terminal
// intermediate
@Override
public Stream<T> filter(Predicate<? super T> predicate) {
throwIfTerminated();
return new StreamImpl<>(this, new FilterSpliterator<>(predicate, spliterator));
}
@Override
public <R> Stream<R> map(Function<? super T, ? extends R> mapper) {
throwIfTerminated();
return new StreamImpl<>(this, new MapToObjSpliterator<>(mapper, spliterator));
}
@Override
public IntStream mapToInt(ToIntFunction<? super T> mapper) {
throwIfTerminated();
return new IntStreamImpl(this, new MapToIntSpliterator<>(mapper, spliterator));
}
@Override
public LongStream mapToLong(ToLongFunction<? super T> mapper) {
throwIfTerminated();
return new LongStreamImpl(this, new MapToLongSpliterator<>(mapper, spliterator));
}
@Override
public DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper) {
throwIfTerminated();
return new DoubleStreamImpl(this, new MapToDoubleSpliterator<>(mapper, spliterator));
}
@Override
public <R> Stream<R> flatMap(final Function<? super T, ? extends Stream<? extends R>> mapper) {
throwIfTerminated();
final Spliterator<? extends Stream<? extends R>> spliteratorOfStreams =
new MapToObjSpliterator<>(mapper, spliterator);
AbstractSpliterator<R> flatMapSpliterator =
new Spliterators.AbstractSpliterator<R>(Long.MAX_VALUE, 0) {
Stream<? extends R> nextStream;
Spliterator<? extends R> next;
@Override
public boolean tryAdvance(Consumer<? super R> action) {
// look for a new spliterator
while (advanceToNextSpliterator()) {
// if we have one, try to read and use it
if (next.tryAdvance(action)) {
return true;
} else {
nextStream.close();
nextStream = null;
// failed, null it out so we can find another
next = null;
}
}
return false;
}
private boolean advanceToNextSpliterator() {
while (next == null) {
if (!spliteratorOfStreams.tryAdvance(
n -> {
if (n != null) {
nextStream = n;
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
return new StreamImpl<R>(this, flatMapSpliterator);
}
@Override
public IntStream flatMapToInt(Function<? super T, ? extends IntStream> mapper) {
throwIfTerminated();
final Spliterator<? extends IntStream> spliteratorOfStreams =
new MapToObjSpliterator<>(mapper, spliterator);
AbstractIntSpliterator flatMapSpliterator =
new Spliterators.AbstractIntSpliterator(Long.MAX_VALUE, 0) {
IntStream nextStream;
Spliterator.OfInt next;
@Override
public boolean tryAdvance(IntConsumer action) {
// look for a new spliterator
while (advanceToNextSpliterator()) {
// if we have one, try to read and use it
if (next.tryAdvance(action)) {
return true;
} else {
nextStream.close();
nextStream = null;
// failed, null it out so we can find another
next = null;
}
}
return false;
}
private boolean advanceToNextSpliterator() {
while (next == null) {
if (!spliteratorOfStreams.tryAdvance(
n -> {
if (n != null) {
nextStream = n;
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
return new IntStreamImpl(this, flatMapSpliterator);
}
@Override
public LongStream flatMapToLong(Function<? super T, ? extends LongStream> mapper) {
throwIfTerminated();
final Spliterator<? extends LongStream> spliteratorOfStreams =
new MapToObjSpliterator<>(mapper, spliterator);
AbstractLongSpliterator flatMapSpliterator =
new Spliterators.AbstractLongSpliterator(Long.MAX_VALUE, 0) {
LongStream nextStream;
Spliterator.OfLong next;
@Override
public boolean tryAdvance(LongConsumer action) {
// look for a new spliterator
while (advanceToNextSpliterator()) {
// if we have one, try to read and use it
if (next.tryAdvance(action)) {
return true;
} else {
nextStream.close();
nextStream = null;
// failed, null it out so we can find another
next = null;
}
}
return false;
}
private boolean advanceToNextSpliterator() {
while (next == null) {
if (!spliteratorOfStreams.tryAdvance(
n -> {
if (n != null) {
nextStream = n;
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
return new LongStreamImpl(this, flatMapSpliterator);
}
@Override
public DoubleStream flatMapToDouble(Function<? super T, ? extends DoubleStream> mapper) {
throwIfTerminated();
final Spliterator<? extends DoubleStream> spliteratorOfStreams =
new MapToObjSpliterator<>(mapper, spliterator);
AbstractDoubleSpliterator flatMapSpliterator =
new Spliterators.AbstractDoubleSpliterator(Long.MAX_VALUE, 0) {
DoubleStream nextStream;
Spliterator.OfDouble next;
@Override
public boolean tryAdvance(DoubleConsumer action) {
// look for a new spliterator
while (advanceToNextSpliterator()) {
// if we have one, try to read and use it
if (next.tryAdvance(action)) {
return true;
} else {
nextStream.close();
nextStream = null;
// failed, null it out so we can find another
next = null;
}
}
return false;
}
private boolean advanceToNextSpliterator() {
while (next == null) {
if (!spliteratorOfStreams.tryAdvance(
n -> {
if (n != null) {
nextStream = n;
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
return new DoubleStreamImpl(this, flatMapSpliterator);
}
@Override
public Stream<T> distinct() {
throwIfTerminated();
HashSet<T> seen = new HashSet<>();
return filter(seen::add);
}
@Override
public Stream<T> sorted() {
throwIfTerminated();
Comparator<T> c = (Comparator) Comparator.naturalOrder();
return sorted(c);
}
@Override
public Stream<T> sorted(final Comparator<? super T> comparator) {
throwIfTerminated();
AbstractSpliterator<T> sortedSpliterator =
new Spliterators.AbstractSpliterator<T>(
spliterator.estimateSize(), spliterator.characteristics() | Spliterator.SORTED) {
Spliterator<T> ordered = null;
@Override
public Comparator<? super T> getComparator() {
return comparator == Comparator.naturalOrder() ? null : comparator;
}
@Override
public boolean tryAdvance(Consumer<? super T> action) {
if (ordered == null) {
List<T> list = new ArrayList<>();
spliterator.forEachRemaining(list::add);
Collections.sort(list, comparator);
ordered = list.spliterator();
}
return ordered.tryAdvance(action);
}
};
return new StreamImpl<>(this, sortedSpliterator);
}
@Override
public Stream<T> peek(final Consumer<? super T> action) {
checkNotNull(action);
throwIfTerminated();
AbstractSpliterator<T> peekSpliterator =
new Spliterators.AbstractSpliterator<T>(
spliterator.estimateSize(), spliterator.characteristics()) {
@Override
public boolean tryAdvance(final Consumer<? super T> innerAction) {
return spliterator.tryAdvance(
item -> {
action.accept(item);
innerAction.accept(item);
});
}
};
return new StreamImpl<>(this, peekSpliterator);
}
@Override
public Stream<T> limit(long maxSize) {
throwIfTerminated();
checkState(maxSize >= 0, "maxSize may not be negative");
return new StreamImpl<>(this, new LimitSpliterator<>(maxSize, spliterator));
}
@Override
public Stream<T> skip(long n) {
throwIfTerminated();
checkState(n >= 0, "n may not be negative");
if (n == 0) {
return this;
}
return new StreamImpl<>(this, new SkipSpliterator<>(n, spliterator));
}
@Override
public boolean isParallel() {
throwIfTerminated();
return false;
}
@Override
public Stream<T> sequential() {
throwIfTerminated();
return this;
}
@Override
public Stream<T> parallel() {
throwIfTerminated();
// do nothing, no such thing as gwt+parallel
return this;
}
@Override
public Stream<T> unordered() {
throwIfTerminated();
return this;
}
}