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com.google.gwt.emul.java.util.stream.DoubleStream Maven / Gradle / Ivy
/*
* 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.Arrays;
import java.util.Comparator;
import java.util.DoubleSummaryStatistics;
import java.util.HashSet;
import java.util.OptionalDouble;
import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.DoubleBinaryOperator;
import java.util.function.DoubleConsumer;
import java.util.function.DoubleFunction;
import java.util.function.DoublePredicate;
import java.util.function.DoubleSupplier;
import java.util.function.DoubleToIntFunction;
import java.util.function.DoubleToLongFunction;
import java.util.function.DoubleUnaryOperator;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;
import java.util.function.ObjDoubleConsumer;
import java.util.function.Supplier;
/**
* See
* the official Java API doc for details.
*/
public interface DoubleStream extends BaseStream {
/**
* Value holder for various stream operations.
*/
static final class ValueConsumer implements DoubleConsumer {
double value;
@Override
public void accept(double value) {
this.value = value;
}
}
static DoubleStream.Builder builder() {
return new Builder() {
private double[] items = new double[0];
@Override
public void accept(double t) {
checkState(items != null, "Builder already built");
items[items.length] = t;
}
@Override
public DoubleStream build() {
checkState(items != null, "Builder already built");
DoubleStream stream = Arrays.stream(items);
items = null;
return stream;
}
};
}
static DoubleStream concat(DoubleStream a, DoubleStream b) {
// This is nearly the same as flatMap, but inlined, wrapped around a single spliterator of
// these two objects, and without close() called as the stream progresses. Instead, close is
// invoked as part of the resulting stream's own onClose, so that either can fail without
// affecting the other, and correctly collecting suppressed exceptions.
// TODO replace this flatMap-ish spliterator with one that directly combines the two root
// streams
Spliterator spliteratorOfStreams = Arrays.asList(a, b).spliterator();
Spliterator.OfDouble spliterator =
new Spliterators.AbstractDoubleSpliterator(Long.MAX_VALUE, 0) {
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 {
// 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) {
next = n.spliterator();
}
})) {
return false;
}
}
return true;
}
};
DoubleStream result = new DoubleStreamSource(null, spliterator);
result.onClose(a::close);
result.onClose(b::close);
return result;
}
static DoubleStream empty() {
return new EmptyDoubleStreamSource(null);
}
static DoubleStream generate(DoubleSupplier s) {
Spliterator.OfDouble spliterator =
new Spliterators.AbstractDoubleSpliterator(
Long.MAX_VALUE, Spliterator.IMMUTABLE | Spliterator.ORDERED) {
@Override
public boolean tryAdvance(DoubleConsumer action) {
action.accept(s.getAsDouble());
return true;
}
};
return StreamSupport.doubleStream(spliterator, false);
}
static DoubleStream iterate(double seed, DoubleUnaryOperator f) {
Spliterator.OfDouble spliterator =
new Spliterators.AbstractDoubleSpliterator(
Long.MAX_VALUE, Spliterator.IMMUTABLE | Spliterator.ORDERED) {
private double next = seed;
@Override
public boolean tryAdvance(DoubleConsumer action) {
action.accept(next);
next = f.applyAsDouble(next);
return true;
}
};
return StreamSupport.doubleStream(spliterator, false);
}
static DoubleStream of(double... values) {
return Arrays.stream(values);
}
static DoubleStream of(double t) {
// TODO consider a splittable that returns only a single value
return of(new double[] {t});
}
/**
* See
*
* the official Java API doc for details.
*/
public interface Builder extends DoubleConsumer {
@Override
void accept(double t);
default DoubleStream.Builder add(double t) {
accept(t);
return this;
}
DoubleStream build();
}
boolean allMatch(DoublePredicate predicate);
boolean anyMatch(DoublePredicate predicate);
OptionalDouble average();
Stream boxed();
R collect(Supplier supplier, ObjDoubleConsumer accumulator, BiConsumer combiner);
long count();
DoubleStream distinct();
DoubleStream filter(DoublePredicate predicate);
OptionalDouble findAny();
OptionalDouble findFirst();
DoubleStream flatMap(DoubleFunction mapper);
void forEach(DoubleConsumer action);
void forEachOrdered(DoubleConsumer action);
@Override
PrimitiveIterator.OfDouble iterator();
DoubleStream limit(long maxSize);
DoubleStream map(DoubleUnaryOperator mapper);
IntStream mapToInt(DoubleToIntFunction mapper);
LongStream mapToLong(DoubleToLongFunction mapper);
Stream mapToObj(DoubleFunction mapper);
OptionalDouble max();
OptionalDouble min();
boolean noneMatch(DoublePredicate predicate);
@Override
DoubleStream parallel();
DoubleStream peek(DoubleConsumer action);
OptionalDouble reduce(DoubleBinaryOperator op);
double reduce(double identity, DoubleBinaryOperator op);
@Override
DoubleStream sequential();
DoubleStream skip(long n);
DoubleStream sorted();
@Override
Spliterator.OfDouble spliterator();
double sum();
DoubleSummaryStatistics summaryStatistics();
double[] toArray();
/**
* Represents an empty stream, doing nothing for all methods.
*/
static class EmptyDoubleStreamSource extends TerminatableStream
implements DoubleStream {
public EmptyDoubleStreamSource(TerminatableStream previous) {
super(previous);
}
@Override
public DoubleStream filter(DoublePredicate predicate) {
throwIfTerminated();
return this;
}
@Override
public DoubleStream map(DoubleUnaryOperator mapper) {
throwIfTerminated();
return this;
}
@Override
public Stream mapToObj(DoubleFunction mapper) {
throwIfTerminated();
return new Stream.EmptyStreamSource(this);
}
@Override
public IntStream mapToInt(DoubleToIntFunction mapper) {
throwIfTerminated();
return new IntStream.EmptyIntStreamSource(this);
}
@Override
public LongStream mapToLong(DoubleToLongFunction mapper) {
throwIfTerminated();
return new LongStream.EmptyLongStreamSource(this);
}
@Override
public DoubleStream flatMap(DoubleFunction mapper) {
throwIfTerminated();
return this;
}
@Override
public DoubleStream distinct() {
throwIfTerminated();
return this;
}
@Override
public DoubleStream sorted() {
throwIfTerminated();
return this;
}
@Override
public DoubleStream peek(DoubleConsumer action) {
throwIfTerminated();
return this;
}
@Override
public DoubleStream limit(long maxSize) {
throwIfTerminated();
checkState(maxSize >= 0, "maxSize may not be negative");
return this;
}
@Override
public DoubleStream skip(long n) {
throwIfTerminated();
checkState(n >= 0, "n may not be negative");
return this;
}
@Override
public void forEach(DoubleConsumer action) {
terminate();
// do nothing
}
@Override
public void forEachOrdered(DoubleConsumer action) {
terminate();
// do nothing
}
@Override
public double[] toArray() {
terminate();
return new double[0];
}
@Override
public double reduce(double identity, DoubleBinaryOperator op) {
terminate();
return identity;
}
@Override
public OptionalDouble reduce(DoubleBinaryOperator op) {
terminate();
return OptionalDouble.empty();
}
@Override
public R collect(
Supplier supplier, ObjDoubleConsumer accumulator, BiConsumer combiner) {
terminate();
return supplier.get();
}
@Override
public double sum() {
terminate();
return 0;
}
@Override
public OptionalDouble min() {
terminate();
return OptionalDouble.empty();
}
@Override
public OptionalDouble max() {
terminate();
return OptionalDouble.empty();
}
@Override
public long count() {
terminate();
return 0;
}
@Override
public OptionalDouble average() {
terminate();
return OptionalDouble.empty();
}
@Override
public DoubleSummaryStatistics summaryStatistics() {
terminate();
return new DoubleSummaryStatistics();
}
@Override
public boolean anyMatch(DoublePredicate predicate) {
terminate();
return false;
}
@Override
public boolean allMatch(DoublePredicate predicate) {
terminate();
return true;
}
@Override
public boolean noneMatch(DoublePredicate predicate) {
terminate();
return true;
}
@Override
public OptionalDouble findFirst() {
terminate();
return OptionalDouble.empty();
}
@Override
public OptionalDouble findAny() {
terminate();
return OptionalDouble.empty();
}
@Override
public Stream boxed() {
throwIfTerminated();
return new Stream.EmptyStreamSource(this);
}
@Override
public DoubleStream sequential() {
throwIfTerminated();
return this;
}
@Override
public DoubleStream parallel() {
throwIfTerminated();
return this;
}
@Override
public PrimitiveIterator.OfDouble iterator() {
return Spliterators.iterator(spliterator());
}
@Override
public Spliterator.OfDouble spliterator() {
terminate();
return Spliterators.emptyDoubleSpliterator();
}
@Override
public boolean isParallel() {
throwIfTerminated();
return false;
}
@Override
public DoubleStream unordered() {
throwIfTerminated();
return this;
}
}
/**
* Double to Int map spliterator.
*/
static final class MapToIntSpliterator extends Spliterators.AbstractIntSpliterator {
private final DoubleToIntFunction map;
private final Spliterator.OfDouble original;
public MapToIntSpliterator(DoubleToIntFunction map, Spliterator.OfDouble 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((double u) -> action.accept(map.applyAsInt(u)));
}
}
/**
* Double to Object map spliterator.
* @param the type of Object in the spliterator
*/
static final class MapToObjSpliterator extends Spliterators.AbstractSpliterator {
private final DoubleFunction map;
private final Spliterator.OfDouble original;
public MapToObjSpliterator(DoubleFunction map, Spliterator.OfDouble original) {
super(
original.estimateSize(),
original.characteristics() & ~(Spliterator.SORTED | Spliterator.DISTINCT));
checkNotNull(map);
this.map = map;
this.original = original;
}
@Override
public boolean tryAdvance(final Consumer action) {
return original.tryAdvance((double u) -> action.accept(map.apply(u)));
}
}
/**
* Double to Long map spliterator.
*/
static final class MapToLongSpliterator extends Spliterators.AbstractLongSpliterator {
private final DoubleToLongFunction map;
private final Spliterator.OfDouble original;
public MapToLongSpliterator(DoubleToLongFunction map, Spliterator.OfDouble 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((double u) -> action.accept(map.applyAsLong(u)));
}
}
/**
* Double to Double map spliterator.
*/
static final class MapToDoubleSpliterator extends Spliterators.AbstractDoubleSpliterator {
private final DoubleUnaryOperator map;
private final Spliterator.OfDouble original;
public MapToDoubleSpliterator(DoubleUnaryOperator map, Spliterator.OfDouble 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((double u) -> action.accept(map.applyAsDouble(u)));
}
}
/**
* Double filter spliterator.
*/
static final class FilterSpliterator extends Spliterators.AbstractDoubleSpliterator {
private final DoublePredicate filter;
private final Spliterator.OfDouble original;
private boolean found;
public FilterSpliterator(DoublePredicate filter, Spliterator.OfDouble original) {
super(original.estimateSize(), original.characteristics() & ~Spliterator.SIZED);
checkNotNull(filter);
this.filter = filter;
this.original = original;
}
@Override
public Comparator getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(final DoubleConsumer action) {
found = false;
while (!found
&& original.tryAdvance(
(double item) -> {
if (filter.test(item)) {
found = true;
action.accept(item);
}
})) {
// do nothing, work is done in tryAdvance
}
return found;
}
}
/**
* Double skip spliterator.
*/
static final class SkipSpliterator extends Spliterators.AbstractDoubleSpliterator {
private long skip;
private final Spliterator.OfDouble original;
public SkipSpliterator(long skip, Spliterator.OfDouble 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 getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(DoubleConsumer action) {
while (skip > 0) {
if (!original.tryAdvance((double ignore) -> { })) {
return false;
}
skip--;
}
return original.tryAdvance(action);
}
}
/**
* Double limit spliterator.
*/
static final class LimitSpliterator extends Spliterators.AbstractDoubleSpliterator {
private final long limit;
private final Spliterator.OfDouble original;
private int position = 0;
public LimitSpliterator(long limit, Spliterator.OfDouble 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 getComparator() {
return original.getComparator();
}
@Override
public boolean tryAdvance(DoubleConsumer action) {
if (position >= limit) {
return false;
}
boolean result = original.tryAdvance(action);
position++;
return result;
}
}
/**
* Main implementation of DoubleStream, wrapping a single spliterator, and an optional parent
* stream.
*/
static class DoubleStreamSource extends TerminatableStream
implements DoubleStream {
private final Spliterator.OfDouble spliterator;
public DoubleStreamSource(TerminatableStream previous, Spliterator.OfDouble spliterator) {
super(previous);
this.spliterator = spliterator;
}
// terminals
@Override
public void forEach(DoubleConsumer action) {
forEachOrdered(action);
}
@Override
public void forEachOrdered(DoubleConsumer action) {
terminate();
spliterator.forEachRemaining(action);
}
@Override
public double[] toArray() {
terminate();
double[] entries = new double[0];
// this is legal in js, since the array will be backed by a JS array
spliterator.forEachRemaining((double value) -> entries[entries.length] = value);
return entries;
}
@Override
public double reduce(double identity, DoubleBinaryOperator op) {
terminate();
ValueConsumer holder = new ValueConsumer();
holder.value = identity;
spliterator.forEachRemaining(
(double value) -> {
holder.accept(op.applyAsDouble(holder.value, value));
});
return holder.value;
}
@Override
public OptionalDouble reduce(DoubleBinaryOperator op) {
ValueConsumer holder = new ValueConsumer();
if (spliterator.tryAdvance(holder)) {
return OptionalDouble.of(reduce(holder.value, op));
}
terminate();
return OptionalDouble.empty();
}
@Override
public R collect(
Supplier supplier, ObjDoubleConsumer accumulator, BiConsumer combiner) {
terminate();
final R acc = supplier.get();
spliterator.forEachRemaining((double value) -> accumulator.accept(acc, value));
return acc;
}
@Override
public double sum() {
return summaryStatistics().getSum();
}
@Override
public OptionalDouble min() {
DoubleSummaryStatistics stats = summaryStatistics();
if (stats.getCount() == 0) {
return OptionalDouble.empty();
}
return OptionalDouble.of(stats.getMin());
}
@Override
public OptionalDouble max() {
DoubleSummaryStatistics stats = summaryStatistics();
if (stats.getCount() == 0) {
return OptionalDouble.empty();
}
return OptionalDouble.of(stats.getMax());
}
@Override
public long count() {
terminate();
long count = 0;
while (spliterator.tryAdvance((double value) -> { })) {
count++;
}
return count;
}
@Override
public OptionalDouble average() {
DoubleSummaryStatistics stats = summaryStatistics();
if (stats.getCount() == 0) {
return OptionalDouble.empty();
}
return OptionalDouble.of(stats.getAverage());
}
@Override
public DoubleSummaryStatistics summaryStatistics() {
return collect(
DoubleSummaryStatistics::new,
// TODO switch to a lambda reference once #9340 is fixed
(doubleSummaryStatistics, value) -> doubleSummaryStatistics.accept(value),
DoubleSummaryStatistics::combine);
}
@Override
public boolean anyMatch(DoublePredicate predicate) {
return filter(predicate).findFirst().isPresent();
}
@Override
public boolean allMatch(DoublePredicate predicate) {
return !anyMatch(predicate.negate());
}
@Override
public boolean noneMatch(DoublePredicate predicate) {
return !anyMatch(predicate);
}
@Override
public OptionalDouble findFirst() {
terminate();
ValueConsumer holder = new ValueConsumer();
if (spliterator.tryAdvance(holder)) {
return OptionalDouble.of(holder.value);
}
return OptionalDouble.empty();
}
@Override
public OptionalDouble findAny() {
return findFirst();
}
@Override
public PrimitiveIterator.OfDouble iterator() {
return Spliterators.iterator(spliterator());
}
@Override
public Spliterator.OfDouble spliterator() {
terminate();
return spliterator;
}
// end terminals
// intermediates
@Override
public DoubleStream filter(DoublePredicate predicate) {
throwIfTerminated();
return new DoubleStreamSource(this, new FilterSpliterator(predicate, spliterator));
}
@Override
public DoubleStream map(DoubleUnaryOperator mapper) {
throwIfTerminated();
return new DoubleStreamSource(this, new MapToDoubleSpliterator(mapper, spliterator));
}
@Override
public Stream mapToObj(DoubleFunction mapper) {
throwIfTerminated();
return new Stream.StreamSource(this, new MapToObjSpliterator(mapper, spliterator));
}
@Override
public IntStream mapToInt(DoubleToIntFunction mapper) {
throwIfTerminated();
return new IntStream.IntStreamSource(this, new MapToIntSpliterator(mapper, spliterator));
}
@Override
public LongStream mapToLong(DoubleToLongFunction mapper) {
throwIfTerminated();
return new LongStream.LongStreamSource(this, new MapToLongSpliterator(mapper, spliterator));
}
@Override
public DoubleStream flatMap(DoubleFunction mapper) {
throwIfTerminated();
final Spliterator spliteratorOfStreams =
new MapToObjSpliterator(mapper, spliterator);
Spliterator.OfDouble 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 DoubleStreamSource(this, flatMapSpliterator);
}
@Override
public DoubleStream distinct() {
throwIfTerminated();
HashSet seen = new HashSet<>();
return filter(seen::add);
}
@Override
public DoubleStream sorted() {
throwIfTerminated();
Spliterator.OfDouble sortingSpliterator =
new Spliterators.AbstractDoubleSpliterator(
spliterator.estimateSize(), spliterator.characteristics() | Spliterator.SORTED) {
Spliterator.OfDouble ordered = null;
@Override
public Comparator getComparator() {
return null;
}
@Override
public boolean tryAdvance(DoubleConsumer action) {
if (ordered == null) {
double[] list = new double[0];
spliterator.forEachRemaining((double item) -> list[list.length] = item);
Arrays.sort(list);
ordered = Spliterators.spliterator(list, characteristics());
}
return ordered.tryAdvance(action);
}
};
return new DoubleStreamSource(this, sortingSpliterator);
}
@Override
public DoubleStream peek(DoubleConsumer action) {
checkNotNull(action);
throwIfTerminated();
Spliterator.OfDouble peekSpliterator =
new Spliterators.AbstractDoubleSpliterator(
spliterator.estimateSize(), spliterator.characteristics()) {
@Override
public boolean tryAdvance(final DoubleConsumer innerAction) {
return spliterator.tryAdvance(action.andThen(innerAction));
}
};
return new DoubleStreamSource(this, peekSpliterator);
}
@Override
public DoubleStream limit(long maxSize) {
throwIfTerminated();
checkState(maxSize >= 0, "maxSize may not be negative");
return new DoubleStreamSource(this, new LimitSpliterator(maxSize, spliterator));
}
@Override
public DoubleStream skip(long n) {
throwIfTerminated();
checkState(n >= 0, "n may not be negative");
if (n == 0) {
return this;
}
return new DoubleStreamSource(this, new SkipSpliterator(n, spliterator));
}
@Override
public Stream boxed() {
return mapToObj(Double::valueOf);
}
@Override
public DoubleStream sequential() {
throwIfTerminated();
return this;
}
@Override
public DoubleStream parallel() {
throwIfTerminated();
return this;
}
@Override
public boolean isParallel() {
throwIfTerminated();
return false;
}
@Override
public DoubleStream unordered() {
throwIfTerminated();
return this;
}
}
}
