/*
* Copyright 2015, 2016 Tagir Valeev
*
* 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 one.util.streamex;
import java.nio.Buffer;
import java.util.*;
import java.util.Map.Entry;
import java.util.PrimitiveIterator.OfDouble;
import java.util.concurrent.ForkJoinPool;
import java.util.function.*;
import java.util.stream.*;
import static one.util.streamex.StreamExInternals.*;
/**
* A {@link DoubleStream} implementation with additional functionality
*
* @author Tagir Valeev
*/
public class DoubleStreamEx extends BaseStreamEx<Double, DoubleStream, Spliterator.OfDouble, DoubleStreamEx> implements
DoubleStream {
DoubleStreamEx(DoubleStream stream, StreamContext context) {
super(stream, context);
}
DoubleStreamEx(Spliterator.OfDouble spliterator, StreamContext context) {
super(spliterator, context);
}
@Override
DoubleStream createStream() {
return StreamSupport.doubleStream(spliterator, isParallel());
}
private static DoubleStreamEx seq(DoubleStream stream) {
return new DoubleStreamEx(stream, StreamContext.SEQUENTIAL);
}
final DoubleStreamEx delegate(Spliterator.OfDouble spliterator) {
return new DoubleStreamEx(spliterator, context);
}
@Override
public DoubleStreamEx unordered() {
return (DoubleStreamEx) super.unordered();
}
@Override
public DoubleStreamEx onClose(Runnable closeHandler) {
return (DoubleStreamEx) super.onClose(closeHandler);
}
@Override
public DoubleStreamEx filter(DoublePredicate predicate) {
return new DoubleStreamEx(stream().filter(predicate), context);
}
/**
* Returns a stream consisting of the elements of this stream that don't
* match the given predicate.
*
* <p>
* This is an intermediate operation.
*
* @param predicate a non-interfering, stateless predicate to apply to each
* element to determine if it should be excluded
* @return the new stream
*/
public DoubleStreamEx remove(DoublePredicate predicate) {
return filter(predicate.negate());
}
/**
* Returns a stream consisting of the elements of this stream that strictly
* greater than the specified value.
*
* <p>
* This is an intermediate operation.
*
* @param value a value to compare to
* @return the new stream
* @since 0.2.3
*/
public DoubleStreamEx greater(double value) {
return filter(val -> val > value);
}
/**
* Returns a stream consisting of the elements of this stream that strictly
* less than the specified value.
*
* <p>
* This is an intermediate operation.
*
* @param value a value to compare to
* @return the new stream
* @since 0.2.3
*/
public DoubleStreamEx less(double value) {
return filter(val -> val < value);
}
/**
* Returns a stream consisting of the elements of this stream that greater
* than or equal to the specified value.
*
* <p>
* This is an intermediate operation.
*
* @param value a value to compare to
* @return the new stream
* @since 0.2.3
*/
public DoubleStreamEx atLeast(double value) {
return filter(val -> val >= value);
}
/**
* Returns a stream consisting of the elements of this stream that less than
* or equal to the specified value.
*
* <p>
* This is an intermediate operation.
*
* @param value a value to compare to
* @return the new stream
* @since 0.2.3
*/
public DoubleStreamEx atMost(double value) {
return filter(val -> val <= value);
}
@Override
public DoubleStreamEx map(DoubleUnaryOperator mapper) {
return new DoubleStreamEx(stream().map(mapper), context);
}
/**
* Returns a stream where the first element is the replaced with the result
* of applying the given function while the other elements are left intact.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* @param mapper a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to apply to the first element
* @return the new stream
* @since 0.4.1
*/
public DoubleStreamEx mapFirst(DoubleUnaryOperator mapper) {
return delegate(new PairSpliterator.PSOfDouble((a, b) -> b, mapper, spliterator(),
PairSpliterator.MODE_MAP_FIRST));
}
/**
* Returns a stream where the last element is the replaced with the result
* of applying the given function while the other elements are left intact.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* <p>
* The mapper function is called at most once. It could be not called at all
* if the stream is empty or there is short-circuiting operation downstream.
*
* @param mapper a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to apply to the last element
* @return the new stream
* @since 0.4.1
*/
public DoubleStreamEx mapLast(DoubleUnaryOperator mapper) {
return delegate(new PairSpliterator.PSOfDouble((a, b) -> a, mapper, spliterator(),
PairSpliterator.MODE_MAP_LAST));
}
@Override
public <U> StreamEx<U> mapToObj(DoubleFunction<? extends U> mapper) {
return new StreamEx<>(stream().mapToObj(mapper), context);
}
@Override
public IntStreamEx mapToInt(DoubleToIntFunction mapper) {
return new IntStreamEx(stream().mapToInt(mapper), context);
}
@Override
public LongStreamEx mapToLong(DoubleToLongFunction mapper) {
return new LongStreamEx(stream().mapToLong(mapper), context);
}
/**
* Returns an {@link EntryStream} consisting of the {@link Entry} objects
* which keys and values are results of applying the given functions to the
* elements of this stream.
*
* <p>
* This is an intermediate operation.
*
* @param <K> The {@code Entry} key type
* @param <V> The {@code Entry} value type
* @param keyMapper a non-interfering, stateless function to apply to each
* element
* @param valueMapper a non-interfering, stateless function to apply to each
* element
* @return the new stream
* @since 0.3.1
*/
public <K, V> EntryStream<K, V> mapToEntry(DoubleFunction<? extends K> keyMapper,
DoubleFunction<? extends V> valueMapper) {
return new EntryStream<>(stream().mapToObj(t -> new AbstractMap.SimpleImmutableEntry<>(keyMapper.apply(t),
valueMapper.apply(t))), context);
}
@Override
public DoubleStreamEx flatMap(DoubleFunction<? extends DoubleStream> mapper) {
return new DoubleStreamEx(stream().flatMap(mapper), context);
}
/**
* Returns an {@link IntStreamEx} consisting of the results of replacing
* each element of this stream with the contents of a mapped stream produced
* by applying the provided mapping function to each element. Each mapped
* stream is closed after its contents have been placed into this stream.
* (If a mapped stream is {@code null} an empty stream is used, instead.)
*
* <p>
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless function to apply to each
* element which produces an {@code IntStream} of new values
* @return the new stream
* @since 0.3.0
*/
public IntStreamEx flatMapToInt(DoubleFunction<? extends IntStream> mapper) {
return new IntStreamEx(stream().mapToObj(mapper).flatMapToInt(Function.identity()), context);
}
/**
* Returns a {@link LongStreamEx} consisting of the results of replacing
* each element of this stream with the contents of a mapped stream produced
* by applying the provided mapping function to each element. Each mapped
* stream is closed after its contents have been placed into this stream.
* (If a mapped stream is {@code null} an empty stream is used, instead.)
*
* <p>
* This is an intermediate operation.
*
* @param mapper a non-interfering, stateless function to apply to each
* element which produces a {@code LongStream} of new values
* @return the new stream
* @since 0.3.0
*/
public LongStreamEx flatMapToLong(DoubleFunction<? extends LongStream> mapper) {
return new LongStreamEx(stream().mapToObj(mapper).flatMapToLong(Function.identity()), context);
}
/**
* Returns a {@link StreamEx} consisting of the results of replacing each
* element of this stream with the contents of a mapped stream produced by
* applying the provided mapping function to each element. Each mapped
* stream is closed after its contents have been placed into this stream.
* (If a mapped stream is {@code null} an empty stream is used, instead.)
*
* <p>
* This is an intermediate operation.
*
* @param <R> The element type of the new stream
* @param mapper a non-interfering, stateless function to apply to each
* element which produces a {@code Stream} of new values
* @return the new stream
* @since 0.3.0
*/
public <R> StreamEx<R> flatMapToObj(DoubleFunction<? extends Stream<R>> mapper) {
return new StreamEx<>(stream().mapToObj(mapper).flatMap(Function.identity()), context);
}
/**
* Returns a new stream containing all the elements of the original stream interspersed with
* given delimiter.
*
* <p>
* For example, {@code DoubleStreamEx.of(1, 2, 3).intersperse(4)} will yield a stream containing
* five elements: 1, 4, 2, 4, 3.
*
* <p>
* This is an <a href="package-summary.html#StreamOps">intermediate operation</a>.
*
* @param delimiter a delimiter to be inserted between each pair of elements
* @return the new stream
* @since 0.6.6
*/
public DoubleStreamEx intersperse(int delimiter) {
return new DoubleStreamEx(stream().flatMap(s -> DoubleStreamEx.of(delimiter, s)).skip(1), context);
}
@Override
public DoubleStreamEx distinct() {
return new DoubleStreamEx(stream().distinct(), context);
}
@Override
public DoubleStreamEx sorted() {
return new DoubleStreamEx(stream().sorted(), context);
}
/**
* Returns a stream consisting of the elements of this stream sorted
* according to the given comparator. Stream elements are boxed before
* passing to the comparator.
*
* <p>
* For ordered streams, the sort is stable. For unordered streams, no
* stability guarantees are made.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">stateful intermediate
* operation</a>.
*
* @param comparator a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* {@code Comparator} to be used to compare stream elements
* @return the new stream
*/
public DoubleStreamEx sorted(Comparator<Double> comparator) {
return new DoubleStreamEx(stream().boxed().sorted(comparator).mapToDouble(Double::doubleValue), context);
}
/**
* Returns a stream consisting of the elements of this stream in reverse
* sorted order. The elements are compared for equality according to
* {@link java.lang.Double#compare(double, double)}.
*
* <p>
* This is a stateful intermediate operation.
*
* @return the new stream
* @since 0.0.8
*/
public DoubleStreamEx reverseSorted() {
return new DoubleStreamEx(stream().mapToLong(d -> {
long l = Double.doubleToRawLongBits(d);
return l ^ (((l >>> 63) - 1) | Long.MIN_VALUE);
}).sorted().mapToDouble(l -> Double.longBitsToDouble(l ^ ((-(l >>> 63)) | Long.MIN_VALUE))), context);
}
/**
* Returns a stream consisting of the elements of this stream, sorted
* according to the natural order of the keys extracted by provided
* function.
*
* <p>
* For ordered streams, the sort is stable. For unordered streams, no
* stability guarantees are made.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">stateful intermediate
* operation</a>.
*
* @param <V> the type of the {@code Comparable} sort key
* @param keyExtractor a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to be used to extract sorting keys
* @return the new stream
*/
public <V extends Comparable<? super V>> DoubleStreamEx sortedBy(DoubleFunction<V> keyExtractor) {
return sorted(Comparator.comparing(keyExtractor::apply));
}
/**
* Returns a stream consisting of the elements of this stream, sorted
* according to the int values extracted by provided function.
*
* <p>
* For ordered streams, the sort is stable. For unordered streams, no
* stability guarantees are made.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">stateful intermediate
* operation</a>.
*
* @param keyExtractor a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to be used to extract sorting keys
* @return the new stream
*/
public DoubleStreamEx sortedByInt(DoubleToIntFunction keyExtractor) {
return sorted(Comparator.comparingInt(keyExtractor::applyAsInt));
}
/**
* Returns a stream consisting of the elements of this stream, sorted
* according to the long values extracted by provided function.
*
* <p>
* For ordered streams, the sort is stable. For unordered streams, no
* stability guarantees are made.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">stateful intermediate
* operation</a>.
*
* @param keyExtractor a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to be used to extract sorting keys
* @return the new stream
*/
public DoubleStreamEx sortedByLong(DoubleToLongFunction keyExtractor) {
return sorted(Comparator.comparingLong(keyExtractor::applyAsLong));
}
/**
* Returns a stream consisting of the elements of this stream, sorted
* according to the double values extracted by provided function.
*
* <p>
* For ordered streams, the sort is stable. For unordered streams, no
* stability guarantees are made.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">stateful intermediate
* operation</a>.
*
* @param keyExtractor a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function to be used to extract sorting keys
* @return the new stream
*/
public DoubleStreamEx sortedByDouble(DoubleUnaryOperator keyExtractor) {
return sorted(Comparator.comparingDouble(keyExtractor::applyAsDouble));
}
@Override
public DoubleStreamEx peek(DoubleConsumer action) {
return new DoubleStreamEx(stream().peek(action), context);
}
/**
* Returns a stream consisting of the elements of this stream, additionally
* performing the provided action on the first stream element when it's
* consumed from the resulting stream.
*
* <p>
* This is an <a href="package-summary.html#StreamOps">intermediate
* operation</a>.
*
* <p>
* The action is called at most once. For parallel stream pipelines, it's
* not guaranteed in which thread it will be executed, so if it modifies
* shared state, it is responsible for providing the required
* synchronization.
*
* <p>
* Note that the action might not be called at all if the first element is
* not consumed from the input (for example, if there's short-circuiting
* operation downstream which stopped the stream before the first element).
*
* <p>
* This method exists mainly to support debugging.
*
* @param action a
* <a href="package-summary.html#NonInterference"> non-interfering
* </a> action to perform on the first stream element as it is
* consumed from the stream
* @return the new stream
* @since 0.6.0
*/
public DoubleStreamEx peekFirst(DoubleConsumer action) {
return mapFirst(x -> {
action.accept(x);
return x;
});
}
/**
* Returns a stream consisting of the elements of this stream, additionally
* performing the provided action on the last stream element when it's
* consumed from the resulting stream.
*
* <p>
* This is an <a href="package-summary.html#StreamOps">intermediate
* operation</a>.
*
* <p>
* The action is called at most once. For parallel stream pipelines, it's
* not guaranteed in which thread it will be executed, so if it modifies
* shared state, it is responsible for providing the required
* synchronization.
*
* <p>
* Note that the action might not be called at all if the last element is
* not consumed from the input (for example, if there's short-circuiting
* operation downstream).
*
* <p>
* This method exists mainly to support debugging.
*
* @param action a
* <a href="package-summary.html#NonInterference"> non-interfering
* </a> action to perform on the first stream element as it is
* consumed from the stream
* @return the new stream
* @since 0.6.0
*/
public DoubleStreamEx peekLast(DoubleConsumer action) {
return mapLast(x -> {
action.accept(x);
return x;
});
}
@Override
public DoubleStreamEx limit(long maxSize) {
return new DoubleStreamEx(stream().limit(maxSize), context);
}
@Override
public DoubleStreamEx skip(long n) {
return new DoubleStreamEx(stream().skip(n), context);
}
/**
* Returns a stream consisting of the remaining elements of this stream
* after discarding the first {@code n} elements of the stream. If this
* stream contains fewer than {@code n} elements then an empty stream will
* be returned.
*
* <p>
* This is a stateful quasi-intermediate operation. Unlike
* {@link #skip(long)} it skips the first elements even if the stream is
* unordered. The main purpose of this method is to workaround the problem
* of skipping the first elements from non-sized source with further
* parallel processing and unordered terminal operation (such as
* {@link #forEach(DoubleConsumer)}). This problem was fixed in OracleJDK
* 8u60.
*
* <p>
* Also it behaves much better with infinite streams processed in parallel.
* For example,
* {@code DoubleStreamEx.iterate(0.0, i->i+1).skip(1).limit(100).parallel().toArray()}
* will likely to fail with {@code OutOfMemoryError}, but will work nicely
* if {@code skip} is replaced with {@code skipOrdered}.
*
* <p>
* For sequential streams this method behaves exactly like
* {@link #skip(long)}.
*
* @param n the number of leading elements to skip
* @return the new stream
* @throws IllegalArgumentException if {@code n} is negative
* @see #skip(long)
* @since 0.3.2
*/
public DoubleStreamEx skipOrdered(long n) {
Spliterator.OfDouble spliterator = (isParallel() ? StreamSupport.doubleStream(spliterator(), false) : stream())
.skip(n).spliterator();
return delegate(spliterator);
}
@Override
public void forEach(DoubleConsumer action) {
if (spliterator != null && !isParallel()) {
spliterator().forEachRemaining(action);
} else {
if (context.fjp != null)
context.terminate(() -> {
stream().forEach(action);
return null;
});
else {
stream().forEach(action);
}
}
}
@Override
public void forEachOrdered(DoubleConsumer action) {
if (spliterator != null && !isParallel()) {
spliterator().forEachRemaining(action);
} else {
if (context.fjp != null)
context.terminate(() -> {
stream().forEachOrdered(action);
return null;
});
else {
stream().forEachOrdered(action);
}
}
}
@Override
public double[] toArray() {
if (context.fjp != null)
return context.terminate(stream()::toArray);
return stream().toArray();
}
/**
* Returns a {@code float[]} array containing the elements of this stream
* which are converted to floats using {@code (float)} cast operation.
*
* <p>
* This is a terminal operation.
*
* @return an array containing the elements of this stream
* @since 0.3.0
*/
public float[] toFloatArray() {
if (isParallel())
return collect(DoubleCollector.toFloatArray());
java.util.Spliterator.OfDouble spliterator = spliterator();
long size = spliterator.getExactSizeIfKnown();
FloatBuffer buf;
if (size >= 0 && size <= Integer.MAX_VALUE) {
buf = new FloatBuffer((int) size);
spliterator.forEachRemaining((DoubleConsumer) buf::addUnsafe);
} else {
buf = new FloatBuffer();
spliterator.forEachRemaining((DoubleConsumer) buf::add);
}
return buf.toArray();
}
@Override
public double reduce(double identity, DoubleBinaryOperator op) {
if (context.fjp != null)
return context.terminate(() -> stream().reduce(identity, op));
return stream().reduce(identity, op);
}
@Override
public OptionalDouble reduce(DoubleBinaryOperator op) {
if (context.fjp != null)
return context.terminate(op, stream()::reduce);
return stream().reduce(op);
}
/**
* Folds the elements of this stream using the provided accumulation
* function, going left to right. This is equivalent to:
*
* <pre>
* {@code
* boolean foundAny = false;
* double result = 0;
* for (double element : this stream) {
* if (!foundAny) {
* foundAny = true;
* result = element;
* }
* else
* result = accumulator.apply(result, element);
* }
* return foundAny ? OptionalDouble.of(result) : OptionalDouble.empty();
* }
* </pre>
*
* <p>
* This is a terminal operation.
*
* <p>
* This method cannot take all the advantages of parallel streams as it must
* process elements strictly left to right. If your accumulator function is
* associative, consider using {@link #reduce(DoubleBinaryOperator)} method.
*
* <p>
* For parallel stream it's not guaranteed that accumulator will always be
* executed in the same thread.
*
* @param accumulator a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function for incorporating an additional element into a result
* @return the result of the folding
* @see #foldLeft(double, DoubleBinaryOperator)
* @see #reduce(DoubleBinaryOperator)
* @since 0.4.0
*/
public OptionalDouble foldLeft(DoubleBinaryOperator accumulator) {
PrimitiveBox b = new PrimitiveBox();
forEachOrdered(t -> {
if (b.b)
b.d = accumulator.applyAsDouble(b.d, t);
else {
b.d = t;
b.b = true;
}
});
return b.asDouble();
}
/**
* Folds the elements of this stream using the provided seed object and
* accumulation function, going left to right. This is equivalent to:
*
* <pre>
* {@code
* double result = identity;
* for (double element : this stream)
* result = accumulator.apply(result, element)
* return result;
* }
* </pre>
*
* <p>
* This is a terminal operation.
*
* <p>
* This method cannot take all the advantages of parallel streams as it must
* process elements strictly left to right. If your accumulator function is
* associative, consider using {@link #reduce(double, DoubleBinaryOperator)}
* method.
*
* <p>
* For parallel stream it's not guaranteed that accumulator will always be
* executed in the same thread.
*
* @param seed the starting value
* @param accumulator a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function for incorporating an additional element into a result
* @return the result of the folding
* @see #reduce(double, DoubleBinaryOperator)
* @see #foldLeft(DoubleBinaryOperator)
* @since 0.4.0
*/
public double foldLeft(double seed, DoubleBinaryOperator accumulator) {
double[] box = new double[] { seed };
forEachOrdered(t -> box[0] = accumulator.applyAsDouble(box[0], t));
return box[0];
}
/**
* Produces an array containing cumulative results of applying the
* accumulation function going left to right.
*
* <p>
* This is a terminal operation.
*
* <p>
* For parallel stream it's not guaranteed that accumulator will always be
* executed in the same thread.
*
* <p>
* This method cannot take all the advantages of parallel streams as it must
* process elements strictly left to right.
*
* @param accumulator a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function for incorporating an additional element into a result
* @return the array where the first element is the first element of this
* stream and every successor element is the result of applying
* accumulator function to the previous array element and the
* corresponding stream element. The resulting array has the same
* length as this stream.
* @see #foldLeft(DoubleBinaryOperator)
* @since 0.5.1
*/
public double[] scanLeft(DoubleBinaryOperator accumulator) {
Spliterator.OfDouble spliterator = spliterator();
double size = spliterator.getExactSizeIfKnown();
DoubleBuffer buf = new DoubleBuffer(size >= 0 && size <= Integer.MAX_VALUE ? (int) size : INITIAL_SIZE);
delegate(spliterator).forEachOrdered(i -> buf.add(buf.size == 0 ? i
: accumulator.applyAsDouble(buf.data[buf.size - 1], i)));
return buf.toArray();
}
/**
* Produces an array containing cumulative results of applying the
* accumulation function going left to right using given seed value.
*
* <p>
* This is a terminal operation.
*
* <p>
* For parallel stream it's not guaranteed that accumulator will always be
* executed in the same thread.
*
* <p>
* This method cannot take all the advantages of parallel streams as it must
* process elements strictly left to right.
*
* @param seed the starting value
* @param accumulator a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function for incorporating an additional element into a result
* @return the array where the first element is the seed and every successor
* element is the result of applying accumulator function to the
* previous array element and the corresponding stream element. The
* resulting array is one element longer than this stream.
* @see #foldLeft(double, DoubleBinaryOperator)
* @since 0.5.1
*/
public double[] scanLeft(double seed, DoubleBinaryOperator accumulator) {
return prepend(seed).scanLeft(accumulator);
}
/**
* {@inheritDoc}
*
* @see #collect(DoubleCollector)
*/
@Override
public <R> R collect(Supplier<R> supplier, ObjDoubleConsumer<R> accumulator, BiConsumer<R, R> combiner) {
if (context.fjp != null)
return context.terminate(() -> stream().collect(supplier, accumulator, combiner));
return stream().collect(supplier, accumulator, combiner);
}
/**
* Performs a mutable reduction operation on the elements of this stream
* using an {@link DoubleCollector} which encapsulates the supplier,
* accumulator and merger functions making easier to reuse collection
* strategies.
*
* <p>
* Like {@link #reduce(double, DoubleBinaryOperator)}, {@code collect}
* operations can be parallelized without requiring additional
* synchronization.
*
* <p>
* This is a terminal operation.
*
* @param <A> the intermediate accumulation type of the
* {@code DoubleCollector}
* @param <R> type of the result
* @param collector the {@code DoubleCollector} describing the reduction
* @return the result of the reduction
* @see #collect(Supplier, ObjDoubleConsumer, BiConsumer)
* @since 0.3.0
*/
@SuppressWarnings("unchecked")
public <A, R> R collect(DoubleCollector<A, R> collector) {
if (collector.characteristics().contains(Collector.Characteristics.IDENTITY_FINISH))
return (R) collect(collector.supplier(), collector.doubleAccumulator(), collector.merger());
return collector.finisher().apply(collect(collector.supplier(), collector.doubleAccumulator(), collector
.merger()));
}
@Override
public double sum() {
if (context.fjp != null)
return context.terminate(stream()::sum);
return stream().sum();
}
@Override
public OptionalDouble min() {
return reduce(Math::min);
}
/**
* Returns the minimum element of this stream according to the provided
* {@code Comparator}.
*
* <p>
* This is a terminal operation.
*
* @param comparator a non-interfering, stateless {@link Comparator} to
* compare elements of this stream
* @return an {@code OptionalDouble} describing the minimum element of this
* stream, or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble min(Comparator<Double> comparator) {
return reduce((a, b) -> comparator.compare(a, b) > 0 ? b : a);
}
/**
* Returns the minimum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param <V> the type of the {@code Comparable} sort key
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the lowest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public <V extends Comparable<? super V>> OptionalDouble minBy(DoubleFunction<V> keyExtractor) {
ObjDoubleBox<V> result = collect(() -> new ObjDoubleBox<>(null, 0), (box, i) -> {
V val = Objects.requireNonNull(keyExtractor.apply(i));
if (box.a == null || box.a.compareTo(val) > 0) {
box.a = val;
box.b = i;
}
}, (box1, box2) -> {
if (box2.a != null && (box1.a == null || box1.a.compareTo(box2.a) > 0)) {
box1.a = box2.a;
box1.b = box2.b;
}
});
return result.a == null ? OptionalDouble.empty() : OptionalDouble.of(result.b);
}
/**
* Returns the minimum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the lowest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble minByInt(DoubleToIntFunction keyExtractor) {
return collect(PrimitiveBox::new, (box, d) -> {
int key = keyExtractor.applyAsInt(d);
if (!box.b || box.i > key) {
box.b = true;
box.i = key;
box.d = d;
}
}, PrimitiveBox.MIN_INT).asDouble();
}
/**
* Returns the minimum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the lowest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble minByLong(DoubleToLongFunction keyExtractor) {
return collect(PrimitiveBox::new, (box, d) -> {
long key = keyExtractor.applyAsLong(d);
if (!box.b || box.l > key) {
box.b = true;
box.l = key;
box.d = d;
}
}, PrimitiveBox.MIN_LONG).asDouble();
}
/**
* Returns the minimum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the lowest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble minByDouble(DoubleUnaryOperator keyExtractor) {
double[] result = collect(() -> new double[3], (acc, d) -> {
double key = keyExtractor.applyAsDouble(d);
if (acc[2] == 0 || Double.compare(acc[1], key) > 0) {
acc[0] = d;
acc[1] = key;
acc[2] = 1;
}
}, (acc1, acc2) -> {
if (acc2[2] == 1 && (acc1[2] == 0 || Double.compare(acc1[1], acc2[1]) > 0))
System.arraycopy(acc2, 0, acc1, 0, 3);
});
return result[2] == 1 ? OptionalDouble.of(result[0]) : OptionalDouble.empty();
}
@Override
public OptionalDouble max() {
return reduce(Math::max);
}
/**
* Returns the maximum element of this stream according to the provided
* {@code Comparator}.
*
* <p>
* This is a terminal operation.
*
* @param comparator a non-interfering, stateless {@link Comparator} to
* compare elements of this stream
* @return an {@code OptionalDouble} describing the maximum element of this
* stream, or an empty {@code OptionalDouble} if the stream is empty
*/
public OptionalDouble max(Comparator<Double> comparator) {
return reduce((a, b) -> comparator.compare(a, b) >= 0 ? a : b);
}
/**
* Returns the maximum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param <V> the type of the {@code Comparable} sort key
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the highest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public <V extends Comparable<? super V>> OptionalDouble maxBy(DoubleFunction<V> keyExtractor) {
ObjDoubleBox<V> result = collect(() -> new ObjDoubleBox<>(null, 0), (box, i) -> {
V val = Objects.requireNonNull(keyExtractor.apply(i));
if (box.a == null || box.a.compareTo(val) < 0) {
box.a = val;
box.b = i;
}
}, (box1, box2) -> {
if (box2.a != null && (box1.a == null || box1.a.compareTo(box2.a) < 0)) {
box1.a = box2.a;
box1.b = box2.b;
}
});
return result.a == null ? OptionalDouble.empty() : OptionalDouble.of(result.b);
}
/**
* Returns the maximum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the highest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble maxByInt(DoubleToIntFunction keyExtractor) {
return collect(PrimitiveBox::new, (box, d) -> {
int key = keyExtractor.applyAsInt(d);
if (!box.b || box.i < key) {
box.b = true;
box.i = key;
box.d = d;
}
}, PrimitiveBox.MAX_INT).asDouble();
}
/**
* Returns the maximum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the highest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble maxByLong(DoubleToLongFunction keyExtractor) {
return collect(PrimitiveBox::new, (box, d) -> {
long key = keyExtractor.applyAsLong(d);
if (!box.b || box.l < key) {
box.b = true;
box.l = key;
box.d = d;
}
}, PrimitiveBox.MAX_LONG).asDouble();
}
/**
* Returns the maximum element of this stream according to the provided key
* extractor function.
*
* <p>
* This is a terminal operation.
*
* @param keyExtractor a non-interfering, stateless function
* @return an {@code OptionalDouble} describing the first element of this
* stream for which the highest value was returned by key extractor,
* or an empty {@code OptionalDouble} if the stream is empty
* @since 0.1.2
*/
public OptionalDouble maxByDouble(DoubleUnaryOperator keyExtractor) {
double[] result = collect(() -> new double[3], (acc, d) -> {
double key = keyExtractor.applyAsDouble(d);
if (acc[2] == 0 || Double.compare(acc[1], key) < 0) {
acc[0] = d;
acc[1] = key;
acc[2] = 1;
}
}, (acc1, acc2) -> {
if (acc2[2] == 1 && (acc1[2] == 0 || Double.compare(acc1[1], acc2[1]) < 0))
System.arraycopy(acc2, 0, acc1, 0, 3);
});
return result[2] == 1 ? OptionalDouble.of(result[0]) : OptionalDouble.empty();
}
@Override
public long count() {
if (context.fjp != null)
return context.terminate(stream()::count);
return stream().count();
}
@Override
public OptionalDouble average() {
if (context.fjp != null)
return context.terminate(stream()::average);
return stream().average();
}
@Override
public DoubleSummaryStatistics summaryStatistics() {
return collect(DoubleSummaryStatistics::new, DoubleSummaryStatistics::accept, DoubleSummaryStatistics::combine);
}
@Override
public boolean anyMatch(DoublePredicate predicate) {
if (context.fjp != null)
return context.terminate(predicate, stream()::anyMatch);
return stream().anyMatch(predicate);
}
@Override
public boolean allMatch(DoublePredicate predicate) {
if (context.fjp != null)
return context.terminate(predicate, stream()::allMatch);
return stream().allMatch(predicate);
}
@Override
public boolean noneMatch(DoublePredicate predicate) {
return !anyMatch(predicate);
}
@Override
public OptionalDouble findFirst() {
if (context.fjp != null)
return context.terminate(stream()::findFirst);
return stream().findFirst();
}
/**
* Returns an {@link OptionalDouble} describing the first element of this
* stream, which matches given predicate, or an empty {@code OptionalDouble}
* if there's no matching element.
*
* <p>
* This is a short-circuiting terminal operation.
*
* @param predicate a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* predicate which returned value should match
* @return an {@code OptionalDouble} describing the first matching element
* of this stream, or an empty {@code OptionalDouble} if there's no
* matching element
* @see #findFirst()
*/
public OptionalDouble findFirst(DoublePredicate predicate) {
return filter(predicate).findFirst();
}
@Override
public OptionalDouble findAny() {
if (context.fjp != null)
return context.terminate(stream()::findAny);
return stream().findAny();
}
/**
* Returns an {@link OptionalDouble} describing some element of the stream,
* which matches given predicate, or an empty {@code OptionalDouble} if
* there's no matching element.
*
* <p>
* This is a short-circuiting terminal operation.
*
* <p>
* The behavior of this operation is explicitly nondeterministic; it is free
* to select any element in the stream. This is to allow for maximal
* performance in parallel operations; the cost is that multiple invocations
* on the same source may not return the same result. (If a stable result is
* desired, use {@link #findFirst(DoublePredicate)} instead.)
*
* @param predicate a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* predicate which returned value should match
* @return an {@code OptionalDouble} describing some matching element of
* this stream, or an empty {@code OptionalDouble} if there's no
* matching element
* @see #findAny()
* @see #findFirst(DoublePredicate)
*/
public OptionalDouble findAny(DoublePredicate predicate) {
return filter(predicate).findAny();
}
/**
* Returns an {@link OptionalLong} describing the zero-based index of the
* first element of this stream, which matches given predicate, or an empty
* {@code OptionalLong} if there's no matching element.
*
* <p>
* This is a short-circuiting terminal operation.
*
* @param predicate a
* <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* predicate which returned value should match
* @return an {@code OptionalLong} describing the index of the first
* matching element of this stream, or an empty {@code OptionalLong}
* if there's no matching element.
* @see #findFirst(DoublePredicate)
* @since 0.4.0
*/
public OptionalLong indexOf(DoublePredicate predicate) {
return boxed().indexOf(predicate::test);
}
@Override
public StreamEx<Double> boxed() {
return new StreamEx<>(stream().boxed(), context);
}
@Override
public DoubleStreamEx sequential() {
return (DoubleStreamEx) super.sequential();
}
@Override
public DoubleStreamEx parallel() {
return (DoubleStreamEx) super.parallel();
}
@Override
public DoubleStreamEx parallel(ForkJoinPool fjp) {
return (DoubleStreamEx) super.parallel(fjp);
}
@Override
public OfDouble iterator() {
return Spliterators.iterator(spliterator());
}
/**
* Returns a new {@code DoubleStreamEx} which is a concatenation of this
* stream and the stream containing supplied values
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* @param values the values to append to the stream
* @return the new stream
*/
public DoubleStreamEx append(double... values) {
if (values.length == 0)
return this;
return new DoubleStreamEx(DoubleStream.concat(stream(), DoubleStream.of(values)), context);
}
/**
* Creates a lazily concatenated stream whose elements are all the elements
* of this stream followed by all the elements of the other stream. The
* resulting stream is ordered if both of the input streams are ordered, and
* parallel if either of the input streams is parallel. When the resulting
* stream is closed, the close handlers for both input streams are invoked.
*
* @param other the other stream
* @return this stream appended by the other stream
* @see DoubleStream#concat(DoubleStream, DoubleStream)
*/
public DoubleStreamEx append(DoubleStream other) {
return new DoubleStreamEx(DoubleStream.concat(stream(), other), context.combine(other));
}
/**
* Returns a new {@code DoubleStreamEx} which is a concatenation of the
* stream containing supplied values and this stream
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* @param values the values to prepend to the stream
* @return the new stream
*/
public DoubleStreamEx prepend(double... values) {
if (values.length == 0)
return this;
return new DoubleStreamEx(DoubleStream.concat(DoubleStream.of(values), stream()), context);
}
/**
* Creates a lazily concatenated stream whose elements are all the elements
* of the other stream followed by all the elements of this stream. The
* resulting stream is ordered if both of the input streams are ordered, and
* parallel if either of the input streams is parallel. When the resulting
* stream is closed, the close handlers for both input streams are invoked.
*
* @param other the other stream
* @return this stream prepended by the other stream
* @see DoubleStream#concat(DoubleStream, DoubleStream)
*/
public DoubleStreamEx prepend(DoubleStream other) {
return new DoubleStreamEx(DoubleStream.concat(other, stream()), context.combine(other));
}
/**
* Returns a stream consisting of the results of applying the given function
* to the every adjacent pair of elements of this stream.
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* <p>
* The output stream will contain one element less than this stream. If this
* stream contains zero or one element the output stream will be empty.
*
* @param mapper a non-interfering, stateless function to apply to each
* adjacent pair of this stream elements.
* @return the new stream
* @since 0.2.1
*/
public DoubleStreamEx pairMap(DoubleBinaryOperator mapper) {
return delegate(new PairSpliterator.PSOfDouble(mapper, null, spliterator(), PairSpliterator.MODE_PAIRS));
}
/**
* Returns a {@link String} which is the concatenation of the results of
* calling {@link String#valueOf(double)} on each element of this stream,
* separated by the specified delimiter, in encounter order.
*
* <p>
* This is a terminal operation.
*
* @param delimiter the delimiter to be used between each element
* @return the result of concatenation. For empty input stream empty String
* is returned.
* @since 0.3.1
*/
public String joining(CharSequence delimiter) {
return collect(DoubleCollector.joining(delimiter));
}
/**
* Returns a {@link String} which is the concatenation of the results of
* calling {@link String#valueOf(double)} on each element of this stream,
* separated by the specified delimiter, with the specified prefix and
* suffix in encounter order.
*
* <p>
* This is a terminal operation.
*
* @param delimiter the delimiter to be used between each element
* @param prefix the sequence of characters to be used at the beginning of
* the joined result
* @param suffix the sequence of characters to be used at the end of the
* joined result
* @return the result of concatenation. For empty input stream
* {@code prefix + suffix} is returned.
* @since 0.3.1
*/
public String joining(CharSequence delimiter, CharSequence prefix, CharSequence suffix) {
return collect(DoubleCollector.joining(delimiter, prefix, suffix));
}
/**
* Returns a stream consisting of all elements from this stream until the
* first element which does not match the given predicate is found.
*
* <p>
* This is a short-circuiting stateful operation. It can be either
* <a href="package-summary.html#StreamOps">intermediate or
* quasi-intermediate</a>. When using with JDK 1.9 or higher it calls the
* corresponding JDK 1.9 implementation. When using with JDK 1.8 it uses own
* implementation.
*
* <p>
* While this operation is quite cheap for sequential stream, it can be
* quite expensive on parallel pipelines.
*
* @param predicate a non-interfering, stateless predicate to apply to
* elements.
* @return the new stream.
* @since 0.3.6
* @see #takeWhileInclusive(DoublePredicate)
* @see #dropWhile(DoublePredicate)
*/
public DoubleStreamEx takeWhile(DoublePredicate predicate) {
return VER_SPEC.callWhile(this, Objects.requireNonNull(predicate), false);
}
/**
* Returns a stream consisting of all elements from this stream until the
* first element which does not match the given predicate is found
* (including the first mismatching element).
*
* <p>
* This is a <a href="package-summary.html#StreamOps">quasi-intermediate
* operation</a>.
*
* <p>
* While this operation is quite cheap for sequential stream, it can be
* quite expensive on parallel pipelines.
*
* @param predicate a non-interfering, stateless predicate to apply to
* elements.
* @return the new stream.
* @since 0.5.5
* @see #takeWhile(DoublePredicate)
*/
public DoubleStreamEx takeWhileInclusive(DoublePredicate predicate) {
Objects.requireNonNull(predicate);
return delegate(new TakeDrop.TDOfDouble(spliterator(), false, true, predicate));
}
/**
* Returns a stream consisting of all elements from this stream starting
* from the first element which does not match the given predicate. If the
* predicate is true for all stream elements, an empty stream is returned.
*
* <p>
* This is a stateful operation. It can be either
* <a href="package-summary.html#StreamOps">intermediate or
* quasi-intermediate</a>. When using with JDK 1.9 or higher it calls the
* corresponding JDK 1.9 implementation. When using with JDK 1.8 it uses own
* implementation.
*
* <p>
* While this operation is quite cheap for sequential stream, it can be
* quite expensive on parallel pipelines.
*
* @param predicate a non-interfering, stateless predicate to apply to
* elements.
* @return the new stream.
* @since 0.3.6
*/
public DoubleStreamEx dropWhile(DoublePredicate predicate) {
return VER_SPEC.callWhile(this, Objects.requireNonNull(predicate), true);
}
/**
* Returns a stream containing cumulative results of applying the
* accumulation function going left to right.
*
* <p>
* This is a stateful
* <a href="package-summary.html#StreamOps">quasi-intermediate</a>
* operation.
*
* <p>
* This operation resembles {@link #scanLeft(DoubleBinaryOperator)}, but
* unlike {@code scanLeft} this operation is intermediate and accumulation
* function must be associative.
*
* <p>
* This method cannot take all the advantages of parallel streams as it must
* process elements strictly left to right. Using an unordered source or
* removing the ordering constraint with {@link #unordered()} may improve
* the parallel processing speed.
*
* @param op an <a href="package-summary.html#Associativity">associative</a>
* , <a href="package-summary.html#NonInterference">non-interfering
* </a>, <a href="package-summary.html#Statelessness">stateless</a>
* function for computing the next element based on the previous one
* @return the new stream.
* @see #scanLeft(DoubleBinaryOperator)
* @since 0.6.1
*/
public DoubleStreamEx prefix(DoubleBinaryOperator op) {
return delegate(new PrefixOps.OfDouble(spliterator(), op));
}
// Necessary to generate proper JavaDoc
// does not add overhead as it appears in bytecode anyways as bridge method
@Override
public <U> U chain(Function<? super DoubleStreamEx, U> mapper) {
return mapper.apply(this);
}
/**
* Returns an empty sequential {@code DoubleStreamEx}.
*
* @return an empty sequential stream
*/
public static DoubleStreamEx empty() {
return of(Spliterators.emptyDoubleSpliterator());
}
/**
* Returns a sequential {@code DoubleStreamEx} containing a single element.
*
* @param element the single element
* @return a singleton sequential stream
*/
public static DoubleStreamEx of(double element) {
return of(new ConstSpliterator.OfDouble(element, 1, true));
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} whose elements are
* the specified values.
*
* @param elements the elements of the new stream
* @return the new stream
*/
public static DoubleStreamEx of(double... elements) {
return of(Arrays.spliterator(elements));
}
/**
* Returns a sequential {@link DoubleStreamEx} with the specified range of
* the specified array as its source.
*
* @param array the array, assumed to be unmodified during use
* @param startInclusive the first index to cover, inclusive
* @param endExclusive index immediately past the last index to cover
* @return an {@code DoubleStreamEx} for the array range
* @throws ArrayIndexOutOfBoundsException if {@code startInclusive} is
* negative, {@code endExclusive} is less than
* {@code startInclusive}, or {@code endExclusive} is greater than
* the array size
* @since 0.1.1
* @see Arrays#stream(double[], int, int)
*/
public static DoubleStreamEx of(double[] array, int startInclusive, int endExclusive) {
return of(Arrays.spliterator(array, startInclusive, endExclusive));
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} whose elements are
* the unboxed elements of supplied array.
*
* @param array the array to create the stream from.
* @return the new stream
* @see Arrays#stream(Object[])
* @since 0.5.0
*/
public static DoubleStreamEx of(Double[] array) {
return seq(Arrays.stream(array).mapToDouble(Double::doubleValue));
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} whose elements are
* the values in the supplied {@link java.nio.DoubleBuffer}.
*
* <p>
* The resulting stream covers only a portion of {@code DoubleBuffer}
* content which starts with {@linkplain Buffer#position() position}
* (inclusive) and ends with {@linkplain Buffer#limit() limit} (exclusive).
* Changes in position and limit after the stream creation don't affect the
* stream.
*
* <p>
* The resulting stream does not change the internal {@code DoubleBuffer}
* state.
*
* @param buf the {@code DoubleBuffer} to create a stream from
* @return the new stream
* @since 0.6.2
*/
public static DoubleStreamEx of(java.nio.DoubleBuffer buf) {
return IntStreamEx.range(buf.position(), buf.limit()).mapToDouble(buf::get);
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} whose elements are
* the specified float values casted to double.
*
* @param elements the elements of the new stream
* @return the new stream
* @since 0.2.0
*/
public static DoubleStreamEx of(float... elements) {
return of(elements, 0, elements.length);
}
/**
* Returns a sequential {@link DoubleStreamEx} with the specified range of
* the specified array as its source. Array values will be casted to double.
*
* @param array the array, assumed to be unmodified during use
* @param startInclusive the first index to cover, inclusive
* @param endExclusive index immediately past the last index to cover
* @return an {@code IntStreamEx} for the array range
* @throws ArrayIndexOutOfBoundsException if {@code startInclusive} is
* negative, {@code endExclusive} is less than
* {@code startInclusive}, or {@code endExclusive} is greater than
* the array size
* @since 0.2.0
*/
public static DoubleStreamEx of(float[] array, int startInclusive, int endExclusive) {
rangeCheck(array.length, startInclusive, endExclusive);
return of(new RangeBasedSpliterator.OfFloat(startInclusive, endExclusive, array));
}
/**
* Returns a {@code DoubleStreamEx} object which wraps given
* {@link DoubleStream}.
*
* <p>
* The supplied stream must not be consumed or closed when this method is
* called. No operation must be performed on the supplied stream after it's
* wrapped.
*
* @param stream original stream
* @return the wrapped stream
* @since 0.0.8
*/
public static DoubleStreamEx of(DoubleStream stream) {
return stream instanceof DoubleStreamEx ? (DoubleStreamEx) stream
: new DoubleStreamEx(stream, StreamContext.of(stream));
}
/**
* Returns a sequential {@link DoubleStreamEx} created from given
* {@link java.util.Spliterator.OfDouble}.
*
* @param spliterator a spliterator to create the stream from.
* @return the new stream
* @since 0.3.4
*/
public static DoubleStreamEx of(Spliterator.OfDouble spliterator) {
return new DoubleStreamEx(spliterator, StreamContext.SEQUENTIAL);
}
/**
* Returns a sequential, ordered {@link DoubleStreamEx} created from given
* {@link java.util.PrimitiveIterator.OfDouble}.
*
* <p>
* This method is roughly equivalent to
* {@code DoubleStreamEx.of(Spliterators.spliteratorUnknownSize(iterator, ORDERED))}
* , but may show better performance for parallel processing.
*
* <p>
* Use this method only if you cannot provide better Stream source.
*
* @param iterator an iterator to create the stream from.
* @return the new stream
* @since 0.5.1
*/
public static DoubleStreamEx of(PrimitiveIterator.OfDouble iterator) {
return of(new UnknownSizeSpliterator.USOfDouble(iterator));
}
/**
* Returns a sequential {@code DoubleStreamEx} containing an
* {@link OptionalDouble} value, if present, otherwise returns an empty
* {@code DoubleStreamEx}.
*
* @param optional the optional to create a stream of
* @return a stream with an {@code OptionalDouble} value if present,
* otherwise an empty stream
* @since 0.1.1
*/
public static DoubleStreamEx of(OptionalDouble optional) {
return optional.isPresent() ? of(optional.getAsDouble()) : empty();
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} whose elements are
* the unboxed elements of supplied collection.
*
* @param collection the collection to create the stream from.
* @return the new stream
* @see Collection#stream()
*/
public static DoubleStreamEx of(Collection<Double> collection) {
return seq(collection.stream().mapToDouble(Double::doubleValue));
}
/**
* Returns an effectively unlimited stream of pseudorandom {@code double}
* values, each between zero (inclusive) and one (exclusive) produced by
* given {@link Random} object.
*
* <p>
* A pseudorandom {@code double} value is generated as if it's the result of
* calling the method {@link Random#nextDouble()}.
*
* @param random a {@link Random} object to produce the stream from
* @return a stream of pseudorandom {@code double} values
* @see Random#doubles()
*/
public static DoubleStreamEx of(Random random) {
return seq(random.doubles());
}
/**
* Returns a stream producing the given {@code streamSize} number of
* pseudorandom {@code double} values, each between zero (inclusive) and one
* (exclusive) produced by given {@link Random} object.
*
* <p>
* A pseudorandom {@code double} value is generated as if it's the result of
* calling the method {@link Random#nextDouble()}.
*
* @param random a {@link Random} object to produce the stream from
* @param streamSize the number of values to generate
* @return a stream of pseudorandom {@code double} values
* @see Random#doubles(long)
*/
public static DoubleStreamEx of(Random random, long streamSize) {
return seq(random.doubles(streamSize));
}
/**
* Returns an effectively unlimited stream of pseudorandom {@code double}
* values, each conforming to the given origin (inclusive) and bound
* (exclusive) produced by given {@link Random} object.
*
* @param random a {@link Random} object to produce the stream from
* @param randomNumberOrigin the origin (inclusive) of each random value
* @param randomNumberBound the bound (exclusive) of each random value
* @return a stream of pseudorandom {@code double} values, each with the
* given origin (inclusive) and bound (exclusive)
* @see Random#doubles(double, double)
*/
public static DoubleStreamEx of(Random random, double randomNumberOrigin, double randomNumberBound) {
return seq(random.doubles(randomNumberOrigin, randomNumberBound));
}
/**
* Returns a stream producing the given {@code streamSize} number of
* pseudorandom {@code double} values, each conforming to the given origin
* (inclusive) and bound (exclusive) produced by given {@link Random}
* object.
*
* @param random a {@link Random} object to produce the stream from
* @param randomNumberOrigin the origin (inclusive) of each random value
* @param randomNumberBound the bound (exclusive) of each random value
* @param streamSize the number of values to generate
* @return a stream of pseudorandom {@code double} values, each with the
* given origin (inclusive) and bound (exclusive)
* @see Random#doubles(long, double, double)
*/
public static DoubleStreamEx of(Random random, long streamSize, double randomNumberOrigin,
double randomNumberBound) {
return seq(random.doubles(streamSize, randomNumberOrigin, randomNumberBound));
}
/**
* Returns an infinite sequential ordered {@code DoubleStreamEx} produced by
* iterative application of a function {@code f} to an initial element
* {@code seed}, producing a stream consisting of {@code seed},
* {@code f(seed)}, {@code f(f(seed))}, etc.
*
* <p>
* The first element (position {@code 0}) in the {@code DoubleStreamEx} will
* be the provided {@code seed}. For {@code n > 0}, the element at position
* {@code n}, will be the result of applying the function {@code f} to the
* element at position {@code n - 1}.
*
* @param seed the initial element
* @param f a function to be applied to to the previous element to produce a
* new element
* @return A new sequential {@code DoubleStream}
* @see #iterate(double, DoublePredicate, DoubleUnaryOperator)
*/
public static DoubleStreamEx iterate(final double seed, final DoubleUnaryOperator f) {
return iterate(seed, x -> true, f);
}
/**
* Returns a sequential ordered {@code DoubleStreamEx} produced by iterative
* application of a function to an initial element, conditioned on
* satisfying the supplied predicate. The stream terminates as soon as the
* predicate function returns false.
*
* <p>
* {@code DoubleStreamEx.iterate} should produce the same sequence of
* elements as produced by the corresponding for-loop:
*
* <pre>{@code
* for (double index=seed; predicate.test(index); index = f.apply(index)) {
* ...
* }
* }</pre>
*
* <p>
* The resulting sequence may be empty if the predicate does not hold on the
* seed value. Otherwise the first element will be the supplied seed value,
* the next element (if present) will be the result of applying the function
* f to the seed value, and so on iteratively until the predicate indicates
* that the stream should terminate.
*
* @param seed the initial element
* @param predicate a predicate to apply to elements to determine when the
* stream must terminate.
* @param f a function to be applied to the previous element to produce a
* new element
* @return a new sequential {@code DoubleStreamEx}
* @see #iterate(double, DoubleUnaryOperator)
* @since 0.6.0
*/
public static DoubleStreamEx iterate(double seed, DoublePredicate predicate, DoubleUnaryOperator f) {
Objects.requireNonNull(f);
Objects.requireNonNull(predicate);
Spliterator.OfDouble spliterator = new Spliterators.AbstractDoubleSpliterator(Long.MAX_VALUE,
Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.NONNULL) {
double prev;
boolean started, finished;
@Override
public boolean tryAdvance(DoubleConsumer action) {
Objects.requireNonNull(action);
if (finished)
return false;
double t;
if (started)
t = f.applyAsDouble(prev);
else {
t = seed;
started = true;
}
if (!predicate.test(t)) {
finished = true;
return false;
}
action.accept(prev = t);
return true;
}
@Override
public void forEachRemaining(DoubleConsumer action) {
Objects.requireNonNull(action);
if (finished)
return;
finished = true;
double t = started ? f.applyAsDouble(prev) : seed;
while (predicate.test(t)) {
action.accept(t);
t = f.applyAsDouble(t);
}
}
};
return of(spliterator);
}
/**
* Returns an infinite sequential unordered stream where each element is
* generated by the provided {@code DoubleSupplier}. This is suitable for
* generating constant streams, streams of random elements, etc.
*
* @param s the {@code DoubleSupplier} for generated elements
* @return a new infinite sequential unordered {@code DoubleStreamEx}
* @see DoubleStream#generate(DoubleSupplier)
*/
public static DoubleStreamEx generate(DoubleSupplier s) {
return seq(DoubleStream.generate(s));
}
/**
* Return an ordered stream produced by consecutive calls of the supplied
* producer until it returns false.
*
* <p>
* The producer function may call the passed consumer any number of times
* and return true if the producer should be called again or false
* otherwise. It's guaranteed that the producer will not be called anymore,
* once it returns false.
*
* <p>
* This method is particularly useful when producer changes the mutable
* object which should be left in known state after the full stream
* consumption. Note however that if a short-circuiting operation is used,
* then the final state of the mutable object cannot be guaranteed.
*
* @param producer a predicate which calls the passed consumer to emit
* stream element(s) and returns true if it producer should be
* applied again.
* @return the new stream
* @since 0.6.0
*/
public static DoubleStreamEx produce(Predicate<DoubleConsumer> producer) {
Box<DoubleEmitter> box = new Box<>();
return (box.a = action -> producer.test(action) ? box.a : null).stream();
}
/**
* Returns a sequential unordered {@code DoubleStreamEx} of given length
* which elements are equal to supplied value.
*
* @param value the constant value
* @param length the length of the stream
* @return a new {@code DoubleStreamEx}
* @since 0.1.2
*/
public static DoubleStreamEx constant(double value, long length) {
return of(new ConstSpliterator.OfDouble(value, length, false));
}
/**
* Returns a sequential {@code DoubleStreamEx} containing the results of
* applying the given function to the corresponding pairs of values in given
* two arrays.
*
* @param first the first array
* @param second the second array
* @param mapper a non-interfering, stateless function to apply to each pair
* of the corresponding array elements.
* @return a new {@code DoubleStreamEx}
* @throws IllegalArgumentException if length of the arrays differs.
* @since 0.2.1
*/
public static DoubleStreamEx zip(double[] first, double[] second, DoubleBinaryOperator mapper) {
return of(new RangeBasedSpliterator.ZipDouble(0, checkLength(first.length, second.length), mapper, first,
second));
}
/**
* A helper interface to build a new stream by emitting elements and
* creating new emitters in a chain.
*
* <p>
* Using this interface it's possible to create custom sources which cannot
* be easily expressed using
* {@link DoubleStreamEx#iterate(double, DoubleUnaryOperator)} or
* {@link DoubleStreamEx#generate(DoubleSupplier)}.
*
* @author Tagir Valeev
*
* @since 0.6.0
*/
@FunctionalInterface
public interface DoubleEmitter {
/**
* Calls the supplied consumer zero or more times to emit some elements,
* then returns the next emitter which will emit more, or null if
* nothing more to emit.
*
* <p>
* Normally one element is emitted during the {@code next()} method
* call. However, it's not restricted: you may emit as many elements as
* you want, though in some cases if many elements were emitted they
* might be buffered consuming additional memory.
*
* <p>
* It's allowed not to emit anything (don't call the consumer). However
* if you do this and return new emitter which also does not emit
* anything, you will end up in endless loop.
*
* @param action consumer to be called to emit elements
* @return next emitter or null
*/
DoubleEmitter next(DoubleConsumer action);
/**
* Returns the spliterator which covers all the elements emitted by this
* emitter.
*
* @return the new spliterator
*/
default Spliterator.OfDouble spliterator() {
return new EmitterSpliterator.OfDouble(this);
}
/**
* Returns the stream which covers all the elements emitted by this
* emitter.
*
* @return the new stream
*/
default DoubleStreamEx stream() {
return of(spliterator());
}
}
}