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A general programming library in Java/Android. It's easy to learn and simple to use with concise and powerful APIs.

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/*
 * Copyright (C) 2016, 2017, 2018, 2019 HaiYang Li
 *
 * 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 com.landawn.abacus.util.stream;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Queue;
import java.util.Random;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.BiPredicate;
import java.util.function.BinaryOperator;
import java.util.function.BooleanSupplier;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;

import com.landawn.abacus.annotation.Beta;
import com.landawn.abacus.annotation.IntermediateOp;
import com.landawn.abacus.annotation.LazyEvaluation;
import com.landawn.abacus.annotation.ParallelSupported;
import com.landawn.abacus.annotation.SequentialOnly;
import com.landawn.abacus.annotation.TerminalOp;
import com.landawn.abacus.exception.UncheckedIOException;
import com.landawn.abacus.util.Array;
import com.landawn.abacus.util.AsyncExecutor;
import com.landawn.abacus.util.ByteIterator;
import com.landawn.abacus.util.ByteList;
import com.landawn.abacus.util.ByteSummaryStatistics;
import com.landawn.abacus.util.ClassUtil;
import com.landawn.abacus.util.ContinuableFuture;
import com.landawn.abacus.util.Fn;
import com.landawn.abacus.util.Fn.FnB;
import com.landawn.abacus.util.Holder;
import com.landawn.abacus.util.IOUtil;
import com.landawn.abacus.util.IndexedByte;
import com.landawn.abacus.util.MergeResult;
import com.landawn.abacus.util.MutableInt;
import com.landawn.abacus.util.N;
import com.landawn.abacus.util.Pair;
import com.landawn.abacus.util.Percentage;
import com.landawn.abacus.util.RateLimiter;
import com.landawn.abacus.util.Throwables;
import com.landawn.abacus.util.u.Optional;
import com.landawn.abacus.util.u.OptionalByte;
import com.landawn.abacus.util.u.OptionalDouble;
import com.landawn.abacus.util.function.ByteBiFunction;
import com.landawn.abacus.util.function.ByteBiPredicate;
import com.landawn.abacus.util.function.ByteBinaryOperator;
import com.landawn.abacus.util.function.ByteConsumer;
import com.landawn.abacus.util.function.ByteFunction;
import com.landawn.abacus.util.function.ByteNFunction;
import com.landawn.abacus.util.function.BytePredicate;
import com.landawn.abacus.util.function.ByteSupplier;
import com.landawn.abacus.util.function.ByteTernaryOperator;
import com.landawn.abacus.util.function.ByteToIntFunction;
import com.landawn.abacus.util.function.ByteTriPredicate;
import com.landawn.abacus.util.function.ByteUnaryOperator;
import com.landawn.abacus.util.function.ObjByteConsumer;
import com.landawn.abacus.util.function.ToByteFunction;

/**
 * The Stream will be automatically closed after execution(A terminal method is executed/triggered).
 *
 * @see BaseStream
 * @see Stream
 */
@com.landawn.abacus.annotation.Immutable
@LazyEvaluation
public abstract class ByteStream extends StreamBase {

    static final Random RAND = new SecureRandom();

    ByteStream(final boolean sorted, final Collection closeHandlers) {
        super(sorted, null, closeHandlers);
    }

    @Override
    public ByteStream rateLimited(final RateLimiter rateLimiter) {
        checkArgNotNull(rateLimiter, "rateLimiter");

        final ByteConsumer action = it -> rateLimiter.acquire();

        if (isParallel()) {
            return sequential().onEach(action).parallel(maxThreadNum(), executorNumForVirtualThread(), splitor(), asyncExecutor(), cancelUncompletedThreads());
        } else {
            return onEach(action);
        }
    }

    @Override
    public ByteStream skipUntil(final BytePredicate predicate) {
        assertNotClosed();

        return dropWhile(t -> !predicate.test(t));
    }

    @ParallelSupported
    @IntermediateOp
    public abstract ByteStream map(ByteUnaryOperator mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract IntStream mapToInt(ByteToIntFunction mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract  Stream mapToObj(ByteFunction mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract ByteStream flatMap(ByteFunction mapper);

    // @ParallelSupported
    // @IntermediateOp
    // public abstract ByteStream flatmap(ByteFunction mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract ByteStream flatmap(ByteFunction mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract IntStream flatMapToInt(ByteFunction mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract  Stream flatMapToObj(ByteFunction> mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract  Stream flatmapToObj(ByteFunction> mapper);

    @ParallelSupported
    @IntermediateOp
    public abstract  Stream flattMapToObj(ByteFunction mapper);

    /**
     * Note: copied from StreamEx: https://github.com/amaembo/streamex
     *
     * @param 
     * @param mapper
     * @return
     */
    @Beta
    @ParallelSupported
    @IntermediateOp
    public abstract ByteStream mapPartial(ByteFunction mapper);

    /**
     * Note: copied from StreamEx: https://github.com/amaembo/streamex
     *
     * 
* * Returns a stream consisting of results of applying the given function to * the ranges created from the source elements. * This is a quasi-intermediate * partial reduction operation. * * @param sameRange a non-interfering, stateless predicate to apply to * the leftmost and next elements which returns true for elements * which belong to the same range. * @param mapper a non-interfering, stateless function to apply to the * range borders and produce the resulting element. If value was * not merged to the interval, then mapper will receive the same * value twice, otherwise it will receive the leftmost and the * rightmost values which were merged to the range. * @return * @see #collapse(ByteBiPredicate, ByteBinaryOperator) * @see Stream#rangeMap(BiPredicate, BiFunction) */ @SequentialOnly @IntermediateOp public abstract ByteStream rangeMap(final ByteBiPredicate sameRange, final ByteBinaryOperator mapper); /** * Note: copied from StreamEx: https://github.com/amaembo/streamex * *
* * Returns a stream consisting of results of applying the given function to * the ranges created from the source elements. * This is a quasi-intermediate * partial reduction operation. * * @param sameRange a non-interfering, stateless predicate to apply to * the leftmost and next elements which returns true for elements * which belong to the same range. * @param mapper a non-interfering, stateless function to apply to the * range borders and produce the resulting element. If value was * not merged to the interval, then mapper will receive the same * value twice, otherwise it will receive the leftmost and the * rightmost values which were merged to the range. * @return * @see Stream#rangeMap(BiPredicate, BiFunction) */ @SequentialOnly @IntermediateOp public abstract Stream rangeMapToObj(final ByteBiPredicate sameRange, final ByteBiFunction mapper); /** * Merge series of adjacent elements which satisfy the given predicate using * the merger function and return a new stream. * *
* This method only runs sequentially, even in parallel stream. * * @param collapsible * @return */ @SequentialOnly @IntermediateOp public abstract Stream collapse(final ByteBiPredicate collapsible); /** * Merge series of adjacent elements which satisfy the given predicate using * the merger function and return a new stream. * *
* This method only runs sequentially, even in parallel stream. * * @param collapsible * @param mergeFunction * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream collapse(final ByteBiPredicate collapsible, final ByteBinaryOperator mergeFunction); /** * * @param collapsible test the current element with the first element and previous element in the series. The first parameter is the first element of this series, the second parameter is the previous element and the third parameter is the current element. * @param mergeFunction * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream collapse(final ByteTriPredicate collapsible, final ByteBinaryOperator mergeFunction); /** * Returns a {@code Stream} produced by iterative application of a accumulation function * to an initial element {@code init} and next element of the current stream. * Produces a {@code Stream} consisting of {@code init}, {@code acc(init, value1)}, * {@code acc(acc(init, value1), value2)}, etc. * *

This is an intermediate operation. * *

Example: *

     * accumulator: (a, b) -> a + b
     * stream: [1, 2, 3, 4, 5]
     * result: [1, 3, 6, 10, 15]
     * 
* *
* This method only runs sequentially, even in parallel stream. * * @param accumulator the accumulation function * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream scan(final ByteBinaryOperator accumulator); /** * Returns a {@code Stream} produced by iterative application of a accumulation function * to an initial element {@code init} and next element of the current stream. * Produces a {@code Stream} consisting of {@code init}, {@code acc(init, value1)}, * {@code acc(acc(init, value1), value2)}, etc. * *

This is an intermediate operation. * *

Example: *

     * init:10
     * accumulator: (a, b) -> a + b
     * stream: [1, 2, 3, 4, 5]
     * result: [11, 13, 16, 20, 25]
     * 
* *
* This method only runs sequentially, even in parallel stream. * * @param init the initial value. it's only used once by accumulator to calculate the fist element in the returned stream. * It will be ignored if this stream is empty and won't be the first element of the returned stream. * * @param accumulator the accumulation function * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream scan(final byte init, final ByteBinaryOperator accumulator); /** * * @param init * @param accumulator * @param initIncluded * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream scan(final byte init, final ByteBinaryOperator accumulator, final boolean initIncluded); @SequentialOnly @IntermediateOp public abstract ByteStream prepend(final byte... a); @SequentialOnly @IntermediateOp public abstract ByteStream append(final byte... a); @SequentialOnly @IntermediateOp public abstract ByteStream appendIfEmpty(final byte... a); @SequentialOnly @TerminalOp public abstract ByteList toByteList(); /** * * @param keyMapper * @param valueMapper * @return * @see Collectors#toMap(Throwables.Function, Throwables.Function) */ @ParallelSupported @TerminalOp public abstract Map toMap(Throwables.ByteFunction keyMapper, Throwables.ByteFunction valueMapper) throws E, E2; /** * * @param keyMapper * @param valueMapper * @param mapFactory * @return * @see Collectors#toMap(Throwables.Function, Throwables.Function, Supplier) */ @ParallelSupported @TerminalOp public abstract , E extends Exception, E2 extends Exception> M toMap(Throwables.ByteFunction keyMapper, Throwables.ByteFunction valueMapper, Supplier mapFactory) throws E, E2; /** * * @param keyMapper * @param valueMapper * @param mergeFunction * @return * @see Collectors#toMap(Throwables.Function, Throwables.Function, BinaryOperator) */ @ParallelSupported @TerminalOp public abstract Map toMap(Throwables.ByteFunction keyMapper, Throwables.ByteFunction valueMapper, BinaryOperator mergeFunction) throws E, E2; /** * * @param keyMapper * @param valueMapper * @param mergeFunction * @param mapFactory * @return * @see Collectors#toMap(Throwables.Function, Throwables.Function, BinaryOperator, Supplier) */ @ParallelSupported @TerminalOp public abstract , E extends Exception, E2 extends Exception> M toMap(Throwables.ByteFunction keyMapper, Throwables.ByteFunction valueMapper, BinaryOperator mergeFunction, Supplier mapFactory) throws E, E2; /** * * @param keyMapper * @param downstream * @return * @see Collectors#groupingBy(Throwables.Function, Collector) */ @ParallelSupported @TerminalOp public abstract Map groupTo(Throwables.ByteFunction keyMapper, final Collector downstream) throws E; /** * * @param keyMapper * @param downstream * @param mapFactory * @return * @see Collectors#groupingBy(Throwables.Function, Collector, Supplier) */ @ParallelSupported @TerminalOp public abstract , E extends Exception> M groupTo(Throwables.ByteFunction keyMapper, final Collector downstream, final Supplier mapFactory) throws E; /** * * @param identity * @param op * @return */ @ParallelSupported @TerminalOp public abstract byte reduce(byte identity, ByteBinaryOperator op); /** * * @param op * @return */ @ParallelSupported @TerminalOp public abstract OptionalByte reduce(ByteBinaryOperator op); /** * * @param supplier * @param accumulator * @param combiner * @return * @see Stream#collect(Supplier, BiConsumer, BiConsumer) */ @ParallelSupported @TerminalOp public abstract R collect(Supplier supplier, ObjByteConsumer accumulator, BiConsumer combiner); /** * Only call this method when the returned type {@code R} is one types: {@code Collection/Map/StringBuilder/Multiset/LongMultiset/Multimap/BooleanList/IntList/.../DoubleList}. * Otherwise, please call {@link #collect(Supplier, ObjByteConsumer, BiConsumer)}. * * @param supplier * @param accumulator * @return * @see #collect(Supplier, ObjByteConsumer, BiConsumer) * @see Stream#collect(Supplier, BiConsumer) * @see Stream#collect(Supplier, BiConsumer, BiConsumer) */ @ParallelSupported @TerminalOp public abstract R collect(Supplier supplier, ObjByteConsumer accumulator); @ParallelSupported @TerminalOp public abstract void forEach(Throwables.ByteConsumer action) throws E; @ParallelSupported @TerminalOp public abstract void forEachIndexed(Throwables.IndexedByteConsumer action) throws E; @ParallelSupported @TerminalOp public abstract boolean anyMatch(final Throwables.BytePredicate predicate) throws E; @ParallelSupported @TerminalOp public abstract boolean allMatch(final Throwables.BytePredicate predicate) throws E; @ParallelSupported @TerminalOp public abstract boolean noneMatch(final Throwables.BytePredicate predicate) throws E; @ParallelSupported @TerminalOp public abstract OptionalByte findFirst(final Throwables.BytePredicate predicate) throws E; /** * Returns the first element matched by {@code predicateForFirst} if found or the first element if this stream is not empty * Otherwise an empty {@code OptionalByte} will be returned. * * @param * @param predicateForFirst * @return * @throws E */ @ParallelSupported @TerminalOp public abstract OptionalByte findFirstOrAny(Throwables.BytePredicate predicateForFirst) throws E; /** * Returns the first element matched by {@code predicateForFirst} if found or the last element if this stream is not empty * Otherwise an empty {@code OptionalByte} will be returned. * * @param * @param predicateForFirst * @return * @throws E */ @ParallelSupported @TerminalOp public abstract OptionalByte findFirstOrLast(Throwables.BytePredicate predicateForFirst) throws E; /** * Consider using: {@code stream.reversed().findFirst(predicate)} for better performance if possible. * * @param * @param predicate * @return * @throws E */ @ParallelSupported @TerminalOp public abstract OptionalByte findLast(final Throwables.BytePredicate predicate) throws E; @ParallelSupported @TerminalOp public abstract OptionalByte findAny(final Throwables.BytePredicate predicate) throws E; @SequentialOnly @TerminalOp public abstract OptionalByte min(); @SequentialOnly @TerminalOp public abstract OptionalByte max(); /** * * @param k * @return OptionalByte.empty() if there is no element or count less than k, otherwise the kth largest element. */ @SequentialOnly @TerminalOp public abstract OptionalByte kthLargest(int k); /** * * @return int */ @SequentialOnly @TerminalOp public abstract long sum(); @SequentialOnly @TerminalOp public abstract OptionalDouble average(); @SequentialOnly @TerminalOp public abstract ByteSummaryStatistics summarize(); @SequentialOnly @TerminalOp public abstract Pair>> summarizeAndPercentiles(); /** * * @param b * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return * @deprecated replaced by {@code mergeWith(ByteStream, ByteBiFunction)} * @see #mergeWith(ByteStream, ByteBiFunction) */ @SequentialOnly @IntermediateOp @Deprecated public ByteStream merge(final ByteStream b, final ByteBiFunction nextSelector) { return mergeWith(b, nextSelector); } /** * * @param b * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ @SequentialOnly @IntermediateOp public abstract ByteStream mergeWith(final ByteStream b, final ByteBiFunction nextSelector); @ParallelSupported @IntermediateOp public abstract ByteStream zipWith(ByteStream b, ByteBinaryOperator zipFunction); @ParallelSupported @IntermediateOp public abstract ByteStream zipWith(ByteStream b, ByteStream c, ByteTernaryOperator zipFunction); @ParallelSupported @IntermediateOp public abstract ByteStream zipWith(ByteStream b, byte valueForNoneA, byte valueForNoneB, ByteBinaryOperator zipFunction); @ParallelSupported @IntermediateOp public abstract ByteStream zipWith(ByteStream b, ByteStream c, byte valueForNoneA, byte valueForNoneB, byte valueForNoneC, ByteTernaryOperator zipFunction); @SequentialOnly @IntermediateOp public abstract IntStream asIntStream(); @SequentialOnly @IntermediateOp public abstract Stream boxed(); /** * Remember to close this Stream after the iteration is done, if needed. * * @return */ @Override public ByteIterator iterator() { assertNotClosed(); if (!isEmptyCloseHandlers(closeHandlers) && logger.isWarnEnabled()) { logger.warn("### Remember to close " + ClassUtil.getSimpleClassName(getClass())); } return iteratorEx(); } abstract ByteIteratorEx iteratorEx(); public static ByteStream empty() { return new ArrayByteStream(N.EMPTY_BYTE_ARRAY, true, null); } public static ByteStream ofNullable(final Byte e) { return e == null ? empty() : of(e); } @SafeVarargs public static ByteStream of(final byte... a) { return N.isNullOrEmpty(a) ? empty() : new ArrayByteStream(a); } public static ByteStream of(final byte[] a, final int startIndex, final int endIndex) { return N.isNullOrEmpty(a) && (startIndex == 0 && endIndex == 0) ? empty() : new ArrayByteStream(a, startIndex, endIndex); } public static ByteStream of(final Byte[] a) { return Stream.of(a).mapToByte(FnB.unbox()); } public static ByteStream of(final Byte[] a, final int startIndex, final int endIndex) { return Stream.of(a, startIndex, endIndex).mapToByte(FnB.unbox()); } public static ByteStream of(final Collection c) { return Stream.of(c).mapToByte(FnB.unbox()); } public static ByteStream of(final ByteIterator iterator) { return iterator == null ? empty() : new IteratorByteStream(iterator); } public static ByteStream of(final ByteBuffer buf) { if (buf == null) { return empty(); } return IntStream.range(buf.position(), buf.limit()).mapToByte(buf::get); } public static ByteStream of(final File file) { return of(IOUtil.newFileInputStream(file), true); } public static ByteStream of(final InputStream is) { return of(is, false); } public static ByteStream of(final InputStream is, final boolean closeReaderAferExecution) { if (is == null) { return empty(); } final ByteIterator iter = new ByteIterator() { private final byte[] buf = new byte[8192]; private boolean isEnd = false; private int count = 0; private int idx = 0; @Override public boolean hasNext() { if (idx >= count && !isEnd) { try { count = is.read(buf); idx = 0; isEnd = count <= 0; } catch (IOException e) { throw new UncheckedIOException(e); } } return count > idx; } @Override public byte nextByte() { if (!hasNext()) { throw new NoSuchElementException(); } return buf[idx++]; } }; if (closeReaderAferExecution) { return of(iter).onClose(Fn.close(is)); } else { return of(iter); } } /** * Lazy evaluation. *
* * This is equal to: {@code Stream.just(supplier).flatMapToByte(it -> it.get())}. * * @param * @param supplier * @return */ public static ByteStream defer(final Supplier supplier) { N.checkArgNotNull(supplier, "supplier"); return Stream.just(supplier).flatMapToByte(Supplier::get); } /** * Lazy evaluation. *
* * This is equal to: {@code Stream.just(supplier).flatMapToByte(it -> it.get().stream())}. * * @param supplier * @return */ @Beta public static ByteStream from(final Supplier supplier) { N.checkArgNotNull(supplier, "supplier"); return Stream.just(supplier).flatMapToByte(it -> it.get().stream()); } private static final Function flatMapper = ByteStream::of; private static final Function flattMapper = ByteStream::flatten; public static ByteStream flatten(final byte[][] a) { return N.isNullOrEmpty(a) ? empty() : Stream.of(a).flatMapToByte(flatMapper); } public static ByteStream flatten(final byte[][] a, final boolean vertically) { if (N.isNullOrEmpty(a)) { return empty(); } else if (a.length == 1) { return of(a[0]); } else if (!vertically) { return Stream.of(a).flatMapToByte(flatMapper); } long n = 0; for (byte[] e : a) { n += N.len(e); } if (n == 0) { return empty(); } final int rows = N.len(a); final long count = n; final ByteIterator iter = new ByteIteratorEx() { private int rowNum = 0; private int colNum = 0; private long cnt = 0; @Override public boolean hasNext() { return cnt < count; } @Override public byte nextByte() { if (cnt++ >= count) { throw new NoSuchElementException(); } if (rowNum == rows) { rowNum = 0; colNum++; } while (a[rowNum] == null || colNum >= a[rowNum].length) { if (rowNum < rows - 1) { rowNum++; } else { rowNum = 0; colNum++; } } return a[rowNum++][colNum]; } }; return of(iter); } public static ByteStream flatten(final byte[][] a, final byte valueForNone, final boolean vertically) { if (N.isNullOrEmpty(a)) { return empty(); } else if (a.length == 1) { return of(a[0]); } long n = 0; int maxLen = 0; for (byte[] e : a) { n += N.len(e); maxLen = N.max(maxLen, N.len(e)); } if (n == 0) { return empty(); } final int rows = N.len(a); final int cols = maxLen; final long count = (long) rows * cols; ByteIterator iter = null; if (vertically) { iter = new ByteIteratorEx() { private int rowNum = 0; private int colNum = 0; private long cnt = 0; @Override public boolean hasNext() { return cnt < count; } @Override public byte nextByte() { if (cnt++ >= count) { throw new NoSuchElementException(); } if (rowNum == rows) { rowNum = 0; colNum++; } if (a[rowNum] == null || colNum >= a[rowNum].length) { rowNum++; return valueForNone; } else { return a[rowNum++][colNum]; } } }; } else { iter = new ByteIteratorEx() { private int rowNum = 0; private int colNum = 0; private long cnt = 0; @Override public boolean hasNext() { return cnt < count; } @Override public byte nextByte() { if (cnt++ >= count) { throw new NoSuchElementException(); } if (colNum >= cols) { colNum = 0; rowNum++; } if (a[rowNum] == null || colNum >= a[rowNum].length) { colNum++; return valueForNone; } else { return a[rowNum][colNum++]; } } }; } return of(iter); } public static ByteStream flatten(final byte[][][] a) { return N.isNullOrEmpty(a) ? empty() : Stream.of(a).flatMapToByte(flattMapper); } public static ByteStream range(final byte startInclusive, final byte endExclusive) { if (startInclusive >= endExclusive) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private byte next = startInclusive; private int cnt = endExclusive * 1 - startInclusive; @Override public boolean hasNext() { return cnt > 0; } @Override public byte nextByte() { if (cnt-- <= 0) { throw new NoSuchElementException(); } return next++; } @Override public void advance(long n) { cnt = n >= cnt ? 0 : cnt - (int) n; next += n; } @Override public long count() { return cnt; } @Override public byte[] toArray() { final byte[] result = new byte[cnt]; for (int i = 0; i < cnt; i++) { result[i] = next++; } cnt = 0; return result; } }); } public static ByteStream range(final byte startInclusive, final byte endExclusive, final byte by) { if (by == 0) { throw new IllegalArgumentException("'by' can't be zero"); } if (endExclusive == startInclusive || endExclusive > startInclusive != by > 0) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private byte next = startInclusive; private int cnt = (endExclusive * 1 - startInclusive) / by + ((endExclusive * 1 - startInclusive) % by == 0 ? 0 : 1); @Override public boolean hasNext() { return cnt > 0; } @Override public byte nextByte() { if (cnt-- <= 0) { throw new NoSuchElementException(); } byte result = next; next += by; return result; } @Override public void advance(long n) { cnt = n >= cnt ? 0 : cnt - (int) n; next += n * by; } @Override public long count() { return cnt; } @Override public byte[] toArray() { final byte[] result = new byte[cnt]; for (int i = 0; i < cnt; i++, next += by) { result[i] = next; } cnt = 0; return result; } }); } public static ByteStream rangeClosed(final byte startInclusive, final byte endInclusive) { if (startInclusive > endInclusive) { empty(); } else if (startInclusive == endInclusive) { return of(startInclusive); } return new IteratorByteStream(new ByteIteratorEx() { private byte next = startInclusive; private int cnt = endInclusive * 1 - startInclusive + 1; @Override public boolean hasNext() { return cnt > 0; } @Override public byte nextByte() { if (cnt-- <= 0) { throw new NoSuchElementException(); } return next++; } @Override public void advance(long n) { cnt = n >= cnt ? 0 : cnt - (int) n; next += n; } @Override public long count() { return cnt; } @Override public byte[] toArray() { final byte[] result = new byte[cnt]; for (int i = 0; i < cnt; i++) { result[i] = next++; } cnt = 0; return result; } }); } public static ByteStream rangeClosed(final byte startInclusive, final byte endInclusive, final byte by) { if (by == 0) { throw new IllegalArgumentException("'by' can't be zero"); } if (endInclusive == startInclusive) { return of(startInclusive); } else if (endInclusive > startInclusive != by > 0) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private byte next = startInclusive; private int cnt = (endInclusive * 1 - startInclusive) / by + 1; @Override public boolean hasNext() { return cnt > 0; } @Override public byte nextByte() { if (cnt-- <= 0) { throw new NoSuchElementException(); } byte result = next; next += by; return result; } @Override public void advance(long n) { cnt = n >= cnt ? 0 : cnt - (int) n; next += n * by; } @Override public long count() { return cnt; } @Override public byte[] toArray() { final byte[] result = new byte[cnt]; for (int i = 0; i < cnt; i++, next += by) { result[i] = next; } cnt = 0; return result; } }); } public static ByteStream repeat(final byte element, final long n) { N.checkArgNotNegative(n, "n"); if (n == 0) { return empty(); } else if (n < 10) { return of(Array.repeat(element, (int) n)); } return new IteratorByteStream(new ByteIteratorEx() { private long cnt = n; @Override public boolean hasNext() { return cnt > 0; } @Override public byte nextByte() { if (cnt-- <= 0) { throw new NoSuchElementException(); } return element; } @Override public void advance(long n) { cnt = n >= cnt ? 0 : cnt - (int) n; } @Override public long count() { return cnt; } @Override public byte[] toArray() { final byte[] result = new byte[(int) cnt]; for (int i = 0; i < cnt; i++) { result[i] = element; } cnt = 0; return result; } }); } public static ByteStream random() { final int bound = Byte.MAX_VALUE - Byte.MIN_VALUE + 1; return generate(() -> (byte) (RAND.nextInt(bound) + Byte.MIN_VALUE)); } public static ByteStream iterate(final BooleanSupplier hasNext, final ByteSupplier next) { N.checkArgNotNull(hasNext); N.checkArgNotNull(next); return new IteratorByteStream(new ByteIteratorEx() { private boolean hasNextVal = false; @Override public boolean hasNext() { if (!hasNextVal) { hasNextVal = hasNext.getAsBoolean(); } return hasNextVal; } @Override public byte nextByte() { if (!hasNextVal && !hasNext()) { throw new NoSuchElementException(); } hasNextVal = false; return next.getAsByte(); } }); } public static ByteStream iterate(final byte init, final BooleanSupplier hasNext, final ByteUnaryOperator f) { N.checkArgNotNull(hasNext); N.checkArgNotNull(f); return new IteratorByteStream(new ByteIteratorEx() { private byte t = 0; private boolean isFirst = true; private boolean hasNextVal = false; @Override public boolean hasNext() { if (!hasNextVal) { hasNextVal = hasNext.getAsBoolean(); } return hasNextVal; } @Override public byte nextByte() { if (!hasNextVal && !hasNext()) { throw new NoSuchElementException(); } hasNextVal = false; if (isFirst) { isFirst = false; t = init; } else { t = f.applyAsByte(t); } return t; } }); } /** * * @param init * @param hasNext test if has next by hasNext.test(init) for first time and hasNext.test(f.apply(previous)) for remaining. * @param f * @return */ public static ByteStream iterate(final byte init, final BytePredicate hasNext, final ByteUnaryOperator f) { N.checkArgNotNull(hasNext); N.checkArgNotNull(f); return new IteratorByteStream(new ByteIteratorEx() { private byte t = 0; private byte cur = 0; private boolean isFirst = true; private boolean hasMore = true; private boolean hasNextVal = false; @Override public boolean hasNext() { if (!hasNextVal && hasMore) { if (isFirst) { isFirst = false; hasNextVal = hasNext.test(cur = init); } else { hasNextVal = hasNext.test(cur = f.applyAsByte(t)); } if (!hasNextVal) { hasMore = false; } } return hasNextVal; } @Override public byte nextByte() { if (!hasNextVal && !hasNext()) { throw new NoSuchElementException(); } t = cur; hasNextVal = false; return t; } }); } public static ByteStream iterate(final byte init, final ByteUnaryOperator f) { N.checkArgNotNull(f); return new IteratorByteStream(new ByteIteratorEx() { private byte t = 0; private boolean isFirst = true; @Override public boolean hasNext() { return true; } @Override public byte nextByte() { if (isFirst) { isFirst = false; t = init; } else { t = f.applyAsByte(t); } return t; } }); } public static ByteStream generate(final ByteSupplier s) { N.checkArgNotNull(s); return new IteratorByteStream(new ByteIteratorEx() { @Override public boolean hasNext() { return true; } @Override public byte nextByte() { return s.getAsByte(); } }); } @SafeVarargs public static ByteStream concat(final byte[]... a) { if (N.isNullOrEmpty(a)) { return empty(); } return concat(Arrays.asList(a)); } @SafeVarargs public static ByteStream concat(final ByteIterator... a) { if (N.isNullOrEmpty(a)) { return empty(); } return concatIterators(Array.asList(a)); } @SafeVarargs public static ByteStream concat(final ByteStream... a) { if (N.isNullOrEmpty(a)) { return empty(); } return concat(Array.asList(a)); } @Beta public static ByteStream concat(final List c) { if (N.isNullOrEmpty(c)) { return empty(); } return of(new ByteIteratorEx() { private final Iterator iter = c.iterator(); private byte[] cur; private int cursor = 0; @Override public boolean hasNext() { while ((N.isNullOrEmpty(cur) || cursor >= cur.length) && iter.hasNext()) { cur = iter.next(); cursor = 0; } return cur != null && cursor < cur.length; } @Override public byte nextByte() { if ((cur == null || cursor >= cur.length) && !hasNext()) { throw new NoSuchElementException(); } return cur[cursor++]; } }); } public static ByteStream concat(final Collection c) { return N.isNullOrEmpty(c) ? empty() : new IteratorByteStream(new ByteIteratorEx() { private final Iterator iterators = c.iterator(); private ByteStream cur; private ByteIterator iter; @Override public boolean hasNext() { while ((iter == null || !iter.hasNext()) && iterators.hasNext()) { if (cur != null) { cur.close(); } cur = iterators.next(); iter = cur == null ? null : cur.iteratorEx(); } return iter != null && iter.hasNext(); } @Override public byte nextByte() { if ((iter == null || !iter.hasNext()) && !hasNext()) { throw new NoSuchElementException(); } return iter.nextByte(); } }).onClose(newCloseHandler(c)); } @Beta public static ByteStream concatIterators(final Collection c) { if (N.isNullOrEmpty(c)) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private final Iterator iter = c.iterator(); private ByteIterator cur; @Override public boolean hasNext() { while ((cur == null || !cur.hasNext()) && iter.hasNext()) { cur = iter.next(); } return cur != null && cur.hasNext(); } @Override public byte nextByte() { if ((cur == null || !cur.hasNext()) && !hasNext()) { throw new NoSuchElementException(); } return cur.nextByte(); } }); } /** * Zip together the "a" and "b" arrays until one of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @return */ public static ByteStream zip(final byte[] a, final byte[] b, final ByteBinaryOperator zipFunction) { if (N.isNullOrEmpty(a) || N.isNullOrEmpty(b)) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private final int len = N.min(N.len(a), N.len(b)); private int cursor = 0; @Override public boolean hasNext() { return cursor < len; } @Override public byte nextByte() { if (cursor >= len) { throw new NoSuchElementException(); } return zipFunction.applyAsByte(a[cursor], b[cursor++]); } }); } /** * Zip together the "a", "b" and "c" arrays until one of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param c * @return */ public static ByteStream zip(final byte[] a, final byte[] b, final byte[] c, final ByteTernaryOperator zipFunction) { if (N.isNullOrEmpty(a) || N.isNullOrEmpty(b) || N.isNullOrEmpty(c)) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private final int len = N.min(N.len(a), N.len(b), N.len(c)); private int cursor = 0; @Override public boolean hasNext() { return cursor < len; } @Override public byte nextByte() { if (cursor >= len) { throw new NoSuchElementException(); } return zipFunction.applyAsByte(a[cursor], b[cursor], c[cursor++]); } }); } /** * Zip together the "a" and "b" iterators until one of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @return */ public static ByteStream zip(final ByteIterator a, final ByteIterator b, final ByteBinaryOperator zipFunction) { return new IteratorByteStream(new ByteIteratorEx() { private final ByteIterator iterA = a == null ? ByteIterator.empty() : a; private final ByteIterator iterB = b == null ? ByteIterator.empty() : b; @Override public boolean hasNext() { return iterA.hasNext() && iterB.hasNext(); } @Override public byte nextByte() { return zipFunction.applyAsByte(iterA.nextByte(), iterB.nextByte()); } }); } /** * Zip together the "a", "b" and "c" iterators until one of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @return */ public static ByteStream zip(final ByteIterator a, final ByteIterator b, final ByteIterator c, final ByteTernaryOperator zipFunction) { return new IteratorByteStream(new ByteIteratorEx() { private final ByteIterator iterA = a == null ? ByteIterator.empty() : a; private final ByteIterator iterB = b == null ? ByteIterator.empty() : b; private final ByteIterator iterC = c == null ? ByteIterator.empty() : c; @Override public boolean hasNext() { return iterA.hasNext() && iterB.hasNext() && iterC.hasNext(); } @Override public byte nextByte() { return zipFunction.applyAsByte(iterA.nextByte(), iterB.nextByte(), iterC.nextByte()); } }); } /** * Zip together the "a" and "b" streams until one of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @return */ public static ByteStream zip(final ByteStream a, final ByteStream b, final ByteBinaryOperator zipFunction) { return zip(iterate(a), iterate(b), zipFunction).onClose(newCloseHandler(a, b)); } /** * Zip together the "a", "b" and "c" streams until one of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @return */ public static ByteStream zip(final ByteStream a, final ByteStream b, final ByteStream c, final ByteTernaryOperator zipFunction) { return zip(iterate(a), iterate(b), iterate(c), zipFunction).onClose(newCloseHandler(Array.asList(a, b, c))); } /** * Zip together the iterators until one of them runs out of values. * Each array of values is combined into a single value using the supplied zipFunction function. * * @param c * @param zipFunction * @return */ public static ByteStream zip(final Collection c, final ByteNFunction zipFunction) { return Stream.zip(c, zipFunction).mapToByte(ToByteFunction.UNBOX); } /** * Zip together the "a" and "b" iterators until all of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param valueForNoneA value to fill if "a" runs out of values first. * @param valueForNoneB value to fill if "b" runs out of values first. * @param zipFunction * @return */ public static ByteStream zip(final byte[] a, final byte[] b, final byte valueForNoneA, final byte valueForNoneB, final ByteBinaryOperator zipFunction) { if (N.isNullOrEmpty(a) && N.isNullOrEmpty(b)) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private final int aLen = N.len(a), bLen = N.len(b), len = N.max(aLen, bLen); private int cursor = 0; private byte ret = 0; @Override public boolean hasNext() { return cursor < len; } @Override public byte nextByte() { if (cursor >= len) { throw new NoSuchElementException(); } ret = zipFunction.applyAsByte(cursor < aLen ? a[cursor] : valueForNoneA, cursor < bLen ? b[cursor] : valueForNoneB); cursor++; return ret; } }); } /** * Zip together the "a", "b" and "c" iterators until all of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param c * @param valueForNoneA value to fill if "a" runs out of values. * @param valueForNoneB value to fill if "b" runs out of values. * @param valueForNoneC value to fill if "c" runs out of values. * @param zipFunction * @return */ public static ByteStream zip(final byte[] a, final byte[] b, final byte[] c, final byte valueForNoneA, final byte valueForNoneB, final byte valueForNoneC, final ByteTernaryOperator zipFunction) { if (N.isNullOrEmpty(a) && N.isNullOrEmpty(b) && N.isNullOrEmpty(c)) { return empty(); } return new IteratorByteStream(new ByteIteratorEx() { private final int aLen = N.len(a), bLen = N.len(b), cLen = N.len(c), len = N.max(aLen, bLen, cLen); private int cursor = 0; private byte ret = 0; @Override public boolean hasNext() { return cursor < len; } @Override public byte nextByte() { if (cursor >= len) { throw new NoSuchElementException(); } ret = zipFunction.applyAsByte(cursor < aLen ? a[cursor] : valueForNoneA, cursor < bLen ? b[cursor] : valueForNoneB, cursor < cLen ? c[cursor] : valueForNoneC); cursor++; return ret; } }); } /** * Zip together the "a" and "b" iterators until all of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param valueForNoneA value to fill if "a" runs out of values first. * @param valueForNoneB value to fill if "b" runs out of values first. * @param zipFunction * @return */ public static ByteStream zip(final ByteIterator a, final ByteIterator b, final byte valueForNoneA, final byte valueForNoneB, final ByteBinaryOperator zipFunction) { return new IteratorByteStream(new ByteIteratorEx() { private final ByteIterator iterA = a == null ? ByteIterator.empty() : a; private final ByteIterator iterB = b == null ? ByteIterator.empty() : b; @Override public boolean hasNext() { return iterA.hasNext() || iterB.hasNext(); } @Override public byte nextByte() { if (iterA.hasNext()) { return zipFunction.applyAsByte(iterA.nextByte(), iterB.hasNext() ? iterB.nextByte() : valueForNoneB); } else { return zipFunction.applyAsByte(valueForNoneA, iterB.nextByte()); } } }); } /** * Zip together the "a", "b" and "c" iterators until all of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param c * @param valueForNoneA value to fill if "a" runs out of values. * @param valueForNoneB value to fill if "b" runs out of values. * @param valueForNoneC value to fill if "c" runs out of values. * @param zipFunction * @return */ public static ByteStream zip(final ByteIterator a, final ByteIterator b, final ByteIterator c, final byte valueForNoneA, final byte valueForNoneB, final byte valueForNoneC, final ByteTernaryOperator zipFunction) { return new IteratorByteStream(new ByteIteratorEx() { private final ByteIterator iterA = a == null ? ByteIterator.empty() : a; private final ByteIterator iterB = b == null ? ByteIterator.empty() : b; private final ByteIterator iterC = c == null ? ByteIterator.empty() : c; @Override public boolean hasNext() { return iterA.hasNext() || iterB.hasNext() || iterC.hasNext(); } @Override public byte nextByte() { if (iterA.hasNext()) { return zipFunction.applyAsByte(iterA.nextByte(), iterB.hasNext() ? iterB.nextByte() : valueForNoneB, iterC.hasNext() ? iterC.nextByte() : valueForNoneC); } else if (iterB.hasNext()) { return zipFunction.applyAsByte(valueForNoneA, iterB.nextByte(), iterC.hasNext() ? iterC.nextByte() : valueForNoneC); } else { return zipFunction.applyAsByte(valueForNoneA, valueForNoneB, iterC.nextByte()); } } }); } /** * Zip together the "a" and "b" iterators until all of them runs out of values. * Each pair of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param valueForNoneA value to fill if "a" runs out of values first. * @param valueForNoneB value to fill if "b" runs out of values first. * @param zipFunction * @return */ public static ByteStream zip(final ByteStream a, final ByteStream b, final byte valueForNoneA, final byte valueForNoneB, final ByteBinaryOperator zipFunction) { return zip(iterate(a), iterate(b), valueForNoneA, valueForNoneB, zipFunction).onClose(newCloseHandler(a, b)); } /** * Zip together the "a", "b" and "c" iterators until all of them runs out of values. * Each triple of values is combined into a single value using the supplied zipFunction function. * * @param a * @param b * @param c * @param valueForNoneA value to fill if "a" runs out of values. * @param valueForNoneB value to fill if "b" runs out of values. * @param valueForNoneC value to fill if "c" runs out of values. * @param zipFunction * @return */ public static ByteStream zip(final ByteStream a, final ByteStream b, final ByteStream c, final byte valueForNoneA, final byte valueForNoneB, final byte valueForNoneC, final ByteTernaryOperator zipFunction) { return zip(iterate(a), iterate(b), iterate(c), valueForNoneA, valueForNoneB, valueForNoneC, zipFunction) .onClose(newCloseHandler(Array.asList(a, b, c))); } /** * Zip together the iterators until all of them runs out of values. * Each array of values is combined into a single value using the supplied zipFunction function. * * @param c * @param valuesForNone value to fill for any iterator runs out of values. * @param zipFunction * @return */ public static ByteStream zip(final Collection c, final byte[] valuesForNone, final ByteNFunction zipFunction) { return Stream.zip(c, valuesForNone, zipFunction).mapToByte(ToByteFunction.UNBOX); } /** * * @param a * @param b * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final byte[] a, final byte[] b, final ByteBiFunction nextSelector) { if (N.isNullOrEmpty(a)) { return of(b); } else if (N.isNullOrEmpty(b)) { return of(a); } return new IteratorByteStream(new ByteIteratorEx() { private final int lenA = a.length; private final int lenB = b.length; private int cursorA = 0; private int cursorB = 0; @Override public boolean hasNext() { return cursorA < lenA || cursorB < lenB; } @Override public byte nextByte() { if (cursorA < lenA) { if (cursorB < lenB) { if (nextSelector.apply(a[cursorA], b[cursorB]) == MergeResult.TAKE_FIRST) { return a[cursorA++]; } else { return b[cursorB++]; } } else { return a[cursorA++]; } } else if (cursorB < lenB) { return b[cursorB++]; } else { throw new NoSuchElementException(); } } }); } /** * * @param a * @param b * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final byte[] a, final byte[] b, final byte[] c, final ByteBiFunction nextSelector) { return merge(merge(a, b, nextSelector).iteratorEx(), ByteStream.of(c).iteratorEx(), nextSelector); } /** * * @param a * @param b * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final ByteIterator a, final ByteIterator b, final ByteBiFunction nextSelector) { return new IteratorByteStream(new ByteIteratorEx() { private final ByteIterator iterA = a == null ? ByteIterator.empty() : a; private final ByteIterator iterB = b == null ? ByteIterator.empty() : b; private byte nextA = 0; private byte nextB = 0; private boolean hasNextA = false; private boolean hasNextB = false; @Override public boolean hasNext() { return iterA.hasNext() || iterB.hasNext() || hasNextA || hasNextB; } @Override public byte nextByte() { if (hasNextA) { if (iterB.hasNext()) { if (nextSelector.apply(nextA, (nextB = iterB.nextByte())) == MergeResult.TAKE_FIRST) { hasNextA = false; hasNextB = true; return nextA; } else { return nextB; } } else { hasNextA = false; return nextA; } } else if (hasNextB) { if (iterA.hasNext()) { if (nextSelector.apply((nextA = iterA.nextByte()), nextB) == MergeResult.TAKE_FIRST) { return nextA; } else { hasNextA = true; hasNextB = false; return nextB; } } else { hasNextB = false; return nextB; } } else if (iterA.hasNext()) { if (iterB.hasNext()) { if (nextSelector.apply((nextA = iterA.nextByte()), (nextB = iterB.nextByte())) == MergeResult.TAKE_FIRST) { hasNextB = true; return nextA; } else { hasNextA = true; return nextB; } } else { return iterA.nextByte(); } } else if (iterB.hasNext()) { return iterB.nextByte(); } else { throw new NoSuchElementException(); } } }); } /** * * @param a * @param b * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final ByteIterator a, final ByteIterator b, final ByteIterator c, final ByteBiFunction nextSelector) { return merge(merge(a, b, nextSelector).iteratorEx(), c, nextSelector); } /** * * @param a * @param b * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final ByteStream a, final ByteStream b, final ByteBiFunction nextSelector) { return merge(iterate(a), iterate(b), nextSelector).onClose(newCloseHandler(a, b)); } /** * * @param a * @param b * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final ByteStream a, final ByteStream b, final ByteStream c, final ByteBiFunction nextSelector) { return merge(merge(a, b, nextSelector), c, nextSelector); } /** * * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream merge(final Collection c, final ByteBiFunction nextSelector) { if (N.isNullOrEmpty(c)) { return empty(); } else if (c.size() == 1) { return c.iterator().next(); } else if (c.size() == 2) { final Iterator iter = c.iterator(); return merge(iter.next(), iter.next(), nextSelector); } final Iterator iter = c.iterator(); ByteStream result = merge(iter.next(), iter.next(), nextSelector); while (iter.hasNext()) { result = merge(result, iter.next(), nextSelector); } return result; } /** * All the elements from each input {@code Collection/Iterator/Stream} will be merged into two queues by multiple threads. * Then these two new queues will be merged into one {@code Iterator/Stream} by one thread. * So it's not totally lazy evaluation and may cause out of memory error if there are too many elements merged into the new queues. * Consider using {@code merge}, which is totally lazy evaluation. * * * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @return */ public static ByteStream parallelMerge(final Collection c, final ByteBiFunction nextSelector) { return parallelMerge(c, nextSelector, DEFAULT_MAX_THREAD_NUM); } /** * All the elements from each input {@code Collection/Iterator/Stream} will be merged into two queues by multiple threads. * Then these two new queues will be merged into one {@code Iterator/Stream} by one thread. * So it's not totally lazy evaluation and may cause out of memory error if there are too many elements merged into the new queues. * Consider using {@code merge}, which is totally lazy evaluation. * * * @param c * @param nextSelector first parameter is selected if Nth.FIRST is returned, otherwise the second parameter is selected. * @param maxThreadNum * @return */ public static ByteStream parallelMerge(final Collection c, final ByteBiFunction nextSelector, final int maxThreadNum) { N.checkArgument(maxThreadNum > 0, "'maxThreadNum' must not less than 1"); if (maxThreadNum <= 1) { return merge(c, nextSelector); } else if (N.isNullOrEmpty(c)) { return empty(); } else if (c.size() == 1) { return c.iterator().next(); } else if (c.size() == 2) { final Iterator iter = c.iterator(); return merge(iter.next(), iter.next(), nextSelector); } else if (c.size() == 3) { final Iterator iter = c.iterator(); return merge(iter.next(), iter.next(), iter.next(), nextSelector); } final Supplier supplier = () -> { final Queue queue = N.newLinkedList(); queue.addAll(c); final Holder eHolder = new Holder<>(); final MutableInt cnt = MutableInt.of(c.size()); final List> futureList = new ArrayList<>(c.size() - 1); final int threadNum = N.min(maxThreadNum, c.size() / 2 + 1); AsyncExecutor asyncExecutorToUse = checkAsyncExecutor(DEFAULT_ASYNC_EXECUTOR, threadNum, 0); for (int i = 0; i < threadNum; i++) { asyncExecutorToUse = execute(asyncExecutorToUse, threadNum, 0, i, futureList, () -> { ByteStream a = null; ByteStream b = null; ByteStream c1 = null; try { while (eHolder.value() == null) { synchronized (queue) { if (cnt.intValue() > 2 && queue.size() > 1) { a = queue.poll(); b = queue.poll(); cnt.decrement(); } else { break; } } c1 = ByteStream.of(merge(a, b, nextSelector).toArray()); synchronized (queue) { queue.offer(c1); } } } catch (Throwable e) { setError(eHolder, e); } }); } completeAndShutdownTempExecutor(futureList, eHolder, c, asyncExecutorToUse); return merge(queue.poll(), queue.poll(), nextSelector); }; return Stream.just(supplier).flatMapToByte(Supplier::get); } public static abstract class ByteStreamEx extends ByteStream { private ByteStreamEx(boolean sorted, Collection closeHandlers) { super(sorted, closeHandlers); } } }