StreamUtils.java
- /*
- * *************************************************************************************************************************************************************
- *
- * TheseFoolishThings: Miscellaneous utilities
- * http://tidalwave.it/projects/thesefoolishthings
- *
- * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
- *
- * *************************************************************************************************************************************************************
- *
- * 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.
- *
- * *************************************************************************************************************************************************************
- *
- * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
- * git clone https://github.com/tidalwave-it/thesefoolishthings-src
- *
- * *************************************************************************************************************************************************************
- */
- package it.tidalwave.util;
- import jakarta.annotation.Nonnull;
- import java.time.Instant;
- import java.time.LocalDateTime;
- import java.time.ZoneId;
- import java.time.ZoneOffset;
- import java.util.Random;
- import java.util.Spliterator;
- import java.util.Spliterators;
- import java.util.function.BiFunction;
- import java.util.function.Consumer;
- import java.util.stream.Stream;
- import java.util.stream.StreamSupport;
- import lombok.AccessLevel;
- import lombok.NoArgsConstructor;
- /***************************************************************************************************************************************************************
- *
- * A collection of operations on {@link Stream}s.
- *
- * @author Fabrizio Giudici
- * @since 3.2-ALPHA-12
- * @it.tidalwave.javadoc.draft
- *
- **************************************************************************************************************************************************************/
- @NoArgsConstructor(access = AccessLevel.PRIVATE)
- public final class StreamUtils
- {
- /***********************************************************************************************************************************************************
- * Zips two streams.
- *
- * @param streamA the first {@link Stream}
- * @param streamB the second {@link Stream}
- * @param <A> the type of elements of the first {@link Stream}
- * @param <B> the type of elements of the second {@link Stream}
- * @return the zipped {@link Stream} of {@link Pair}s
- * @see #zip(Stream, Stream, BiFunction)
- * @since 3.2-ALPHA-20
- **********************************************************************************************************************************************************/
- @Nonnull
- public static <A, B> Stream<Pair<A, B>> zip (@Nonnull final Stream<? extends A> streamA,
- @Nonnull final Stream<? extends B> streamB)
- {
- return zip(streamA, streamB, Pair::of);
- }
- /***********************************************************************************************************************************************************
- * Zips two streams.
- *
- * @param streamA the first {@link Stream}
- * @param streamB the second {@link Stream}
- * @param zipper the zipping function
- * @param <A> the type of elements of the first {@link Stream}
- * @param <B> the type of elements of the second {@link Stream}
- * @param <R> the type of elements of the zipped {@link Stream}
- * @return the zipped {@link Stream}
- * @see #zip(Stream, Stream)
- * @since 3.2-ALPHA-12
- **********************************************************************************************************************************************************/
- @Nonnull
- public static <A, B, R> Stream<R> zip (@Nonnull final Stream<? extends A> streamA,
- @Nonnull final Stream<? extends B> streamB,
- @Nonnull final BiFunction<? super A, ? super B, ? extends R> zipper)
- {
- final var parallel = streamA.isParallel() || streamB.isParallel();
- final var sa = streamA.spliterator();
- final var sb = streamB.spliterator();
- final var characteristics =
- sa.characteristics() & sb.characteristics() & (Spliterator.SIZED | Spliterator.ORDERED);
- final var a = Spliterators.iterator(sa);
- final var b = Spliterators.iterator(sb);
- final var estSize = Math.min(sa.estimateSize(), sb.estimateSize());
- return StreamSupport.stream(new Spliterators.AbstractSpliterator<R>(estSize, characteristics)
- {
- @Override
- public boolean tryAdvance (@Nonnull final Consumer<? super R> action)
- {
- if (a.hasNext() && b.hasNext())
- {
- action.accept(zipper.apply(a.next(), b.next()));
- return true;
- }
- return false;
- }
- },
- parallel)
- .onClose(streamA::close)
- .onClose(streamB::close);
- }
- /***********************************************************************************************************************************************************
- * Returns a {@code Stream} of random {@link LocalDateTime}s, in the given range. The used random generator is not strong enough for cryptographic purposes.
- * @param seed the random seed
- * @param from the lower bound of the range (included)
- * @param to the upper bound of the range (excluded)
- * @return the stream
- * @since 3.2-ALPHA-19
- **********************************************************************************************************************************************************/
- @Nonnull
- public static Stream<LocalDateTime> randomLocalDateTimeStream (final long seed,
- @Nonnull final LocalDateTime from,
- @Nonnull final LocalDateTime to)
- {
- final var zo = ZoneOffset.UTC;
- return new Random(seed)
- .longs(from.toEpochSecond(zo), to.toEpochSecond(zo))
- .mapToObj(l -> LocalDateTime.ofInstant(Instant.ofEpochSecond(l), ZoneId.of(zo.getId())));
- }
- }