All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.landawn.abacus.util.stream.AbstractCharStream Maven / Gradle / Ivy

There is a newer version: 1.10.1
Show newest version
/*
 * 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.util.Collection;
import java.util.HashSet;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Random;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

import com.landawn.abacus.exception.DuplicatedResultException;
import com.landawn.abacus.util.CharIterator;
import com.landawn.abacus.util.CharList;
import com.landawn.abacus.util.CharMatrix;
import com.landawn.abacus.util.CharSummaryStatistics;
import com.landawn.abacus.util.Fn;
import com.landawn.abacus.util.Fn.Suppliers;
import com.landawn.abacus.util.IndexedChar;
import com.landawn.abacus.util.Joiner;
import com.landawn.abacus.util.Multiset;
import com.landawn.abacus.util.MutableChar;
import com.landawn.abacus.util.MutableLong;
import com.landawn.abacus.util.N;
import com.landawn.abacus.util.Nth;
import com.landawn.abacus.util.Pair;
import com.landawn.abacus.util.Percentage;
import com.landawn.abacus.util.StringUtil.Strings;
import com.landawn.abacus.util.Try;
import com.landawn.abacus.util.u.Optional;
import com.landawn.abacus.util.u.OptionalChar;
import com.landawn.abacus.util.function.BiConsumer;
import com.landawn.abacus.util.function.BinaryOperator;
import com.landawn.abacus.util.function.CharBiFunction;
import com.landawn.abacus.util.function.CharBiPredicate;
import com.landawn.abacus.util.function.CharBinaryOperator;
import com.landawn.abacus.util.function.CharConsumer;
import com.landawn.abacus.util.function.CharFunction;
import com.landawn.abacus.util.function.CharPredicate;
import com.landawn.abacus.util.function.CharTernaryOperator;
import com.landawn.abacus.util.function.Function;
import com.landawn.abacus.util.function.ObjCharConsumer;
import com.landawn.abacus.util.function.Predicate;
import com.landawn.abacus.util.function.Supplier;
import com.landawn.abacus.util.function.ToCharFunction;

/**
 * 
 */
abstract class AbstractCharStream extends CharStream {

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

    @Override
    public CharStream distinct() {
        final Set set = new HashSet<>();

        return newStream(this.sequential().filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                return set.add(value);
            }
        }).iteratorEx(), sorted);
    }

    @Override
    public CharStream flattMap(final CharFunction mapper) {
        return flatMap(new CharFunction() {
            @Override
            public CharStream apply(char t) {
                return CharStream.of(mapper.apply(t));
            }
        });
    }

    @Override
    public  Stream flattMapToObj(final CharFunction> mapper) {
        return flatMapToObj(new CharFunction>() {
            @Override
            public Stream apply(char t) {
                return Stream.of(mapper.apply(t));
            }
        });
    }

    @Override
    public  Stream flatMappToObj(final CharFunction mapper) {
        return flatMapToObj(new CharFunction>() {
            @Override
            public Stream apply(char t) {
                return Stream.of(mapper.apply(t));
            }
        });
    }

    @Override
    public CharStream rangeMap(final CharBiPredicate sameRange, final CharBinaryOperator mapper) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new CharIteratorEx() {
            private char left = 0, right = 0, next = 0;
            private boolean hasNext = false;

            @Override
            public boolean hasNext() {
                return hasNext || iter.hasNext();
            }

            @Override
            public char nextChar() {
                left = hasNext ? next : iter.nextChar();
                right = left;

                while (hasNext = iter.hasNext()) {
                    next = iter.nextChar();

                    if (sameRange.test(left, next)) {
                        right = next;
                    } else {
                        break;
                    }
                }

                return mapper.applyAsChar(left, right);
            }
        }, false);
    }

    @Override
    public  Stream rangeMapp(final CharBiPredicate sameRange, final CharBiFunction mapper) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new ObjIteratorEx() {
            private char left = 0, right = 0, next = 0;
            private boolean hasNext = false;

            @Override
            public boolean hasNext() {
                return hasNext || iter.hasNext();
            }

            @Override
            public T next() {
                left = hasNext ? next : iter.nextChar();
                right = left;

                while (hasNext = iter.hasNext()) {
                    next = iter.nextChar();

                    if (sameRange.test(left, next)) {
                        right = next;
                    } else {
                        break;
                    }
                }

                return mapper.apply(left, right);
            }
        }, false, null);
    }

    @Override
    public Stream collapse(final CharBiPredicate collapsible) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new ObjIteratorEx() {
            private boolean hasNext = false;
            private char next = 0;

            @Override
            public boolean hasNext() {
                return hasNext || iter.hasNext();
            }

            @Override
            public CharList next() {
                final CharList result = new CharList(9);
                result.add(hasNext ? next : (next = iter.nextChar()));

                while ((hasNext = iter.hasNext())) {
                    if (collapsible.test(next, (next = iter.nextChar()))) {
                        result.add(next);
                    } else {
                        break;
                    }
                }

                return result;
            }
        }, false, null);
    }

    @Override
    public CharStream collapse(final CharBiPredicate collapsible, final CharBinaryOperator mergeFunction) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new CharIteratorEx() {
            private boolean hasNext = false;
            private char next = 0;

            @Override
            public boolean hasNext() {
                return hasNext || iter.hasNext();
            }

            @Override
            public char nextChar() {
                char res = hasNext ? next : (next = iter.nextChar());

                while ((hasNext = iter.hasNext())) {
                    if (collapsible.test(next, (next = iter.nextChar()))) {
                        res = mergeFunction.applyAsChar(res, next);
                    } else {
                        break;
                    }
                }

                return res;
            }
        }, false);
    }

    @Override
    public CharStream skip(final long n, final CharConsumer action) {
        final CharPredicate filter = isParallel() ? new CharPredicate() {
            final AtomicLong cnt = new AtomicLong(n);

            @Override
            public boolean test(char value) {
                return cnt.getAndDecrement() > 0;
            }
        } : new CharPredicate() {
            final MutableLong cnt = MutableLong.of(n);

            @Override
            public boolean test(char value) {
                return cnt.getAndDecrement() > 0;
            }
        };

        return dropWhile(filter, action);
    }

    @Override
    public CharStream removeIf(final CharPredicate predicate) {
        checkArgNotNull(predicate);

        return filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                return predicate.test(value) == false;
            }
        });
    }

    @Override
    public CharStream removeIf(final CharPredicate predicate, final CharConsumer action) {
        checkArgNotNull(predicate);
        checkArgNotNull(predicate);

        return filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                if (predicate.test(value)) {
                    action.accept(value);
                    return false;
                }

                return true;
            }
        });
    }

    @Override
    public CharStream dropWhile(final CharPredicate predicate, final CharConsumer action) {
        checkArgNotNull(predicate);
        checkArgNotNull(action);

        return dropWhile(new CharPredicate() {
            @Override
            public boolean test(char value) {
                if (predicate.test(value)) {
                    action.accept(value);
                    return true;
                }

                return false;
            }
        });
    }

    @Override
    public CharStream step(final long step) {
        checkArgPositive(step, "step");

        final long skip = step - 1;
        final CharIteratorEx iter = this.iteratorEx();

        final CharIterator charIterator = new CharIteratorEx() {
            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public char nextChar() {
                final char next = iter.nextChar();
                iter.skip(skip);
                return next;
            }
        };

        return newStream(charIterator, sorted);
    }

    @Override
    public Stream split(final int chunkSize) {
        return splitToList(chunkSize).map(new Function() {
            @Override
            public CharStream apply(CharList t) {
                return new ArrayCharStream(t.array(), 0, t.size(), sorted, null);
            }
        });
    }

    @Override
    public Stream split(final CharPredicate predicate) {
        return splitToList(predicate).map(new Function() {
            @Override
            public CharStream apply(CharList t) {
                return new ArrayCharStream(t.array(), 0, t.size(), sorted, null);
            }
        });
    }

    @Override
    public Stream splitBy(final CharPredicate where) {
        checkArgNotNull(where);

        final CharIteratorEx iter = iteratorEx();

        return newStream(new ObjIteratorEx() {
            private int cursor = 0;
            private char next = 0;
            private boolean hasNext = false;

            @Override
            public boolean hasNext() {
                return cursor < 2;
            }

            @Override
            public CharStream next() {
                if (hasNext() == false) {
                    throw new NoSuchElementException();
                }

                CharStream result = null;

                if (cursor == 0) {
                    final CharList list = new CharList();

                    while (iter.hasNext()) {
                        next = iter.nextChar();

                        if (where.test(next)) {
                            list.add(next);
                        } else {
                            hasNext = true;
                            break;
                        }
                    }

                    result = new ArrayCharStream(list.array(), 0, list.size(), sorted, null);
                } else {
                    CharIteratorEx iterEx = iter;

                    if (hasNext) {
                        iterEx = new CharIteratorEx() {
                            private boolean isFirst = true;

                            @Override
                            public boolean hasNext() {
                                return isFirst || iter.hasNext();
                            }

                            @Override
                            public char nextChar() {
                                if (hasNext() == false) {
                                    throw new NoSuchElementException();
                                }

                                if (isFirst) {
                                    isFirst = false;
                                    return next;
                                } else {
                                    return iter.nextChar();
                                }
                            }
                        };
                    }

                    result = new IteratorCharStream(iterEx, sorted, null);
                }

                cursor++;

                return result;
            }

            @Override
            public long count() {
                iter.count();

                return 2 - cursor;
            }

            @Override
            public void skip(long n) {
                if (n == 0) {
                    return;
                } else if (n == 1) {
                    if (cursor == 0) {
                        while (iter.hasNext()) {
                            next = iter.nextChar();

                            if (where.test(next) == false) {
                                hasNext = true;
                                break;
                            }
                        }
                    } else {
                        iter.skip(Long.MAX_VALUE);
                    }
                } else {
                    iter.skip(Long.MAX_VALUE);
                }

                cursor = n >= 2 ? 2 : cursor + (int) n;
            }

        }, false, null);
    }

    @Override
    public Stream sliding(final int windowSize, final int increment) {
        return slidingToList(windowSize, increment).map(new Function() {
            @Override
            public CharStream apply(CharList t) {
                return new ArrayCharStream(t.array(), 0, t.size(), sorted, null);
            }
        });
    }

    @Override
    public CharStream scan(final CharBinaryOperator accumulator) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new CharIteratorEx() {
            private char res = 0;
            private boolean isFirst = true;

            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public char nextChar() {
                if (isFirst) {
                    isFirst = false;
                    return (res = iter.nextChar());
                } else {
                    return (res = accumulator.applyAsChar(res, iter.nextChar()));
                }
            }
        }, false);
    }

    @Override
    public CharStream scan(final char init, final CharBinaryOperator accumulator) {
        final CharIteratorEx iter = iteratorEx();

        return newStream(new CharIteratorEx() {
            private char res = init;

            @Override
            public boolean hasNext() {
                return iter.hasNext();
            }

            @Override
            public char nextChar() {
                return (res = accumulator.applyAsChar(res, iter.nextChar()));
            }
        }, false);
    }

    @Override
    public CharStream scan(final char init, final CharBinaryOperator accumulator, final boolean initIncluded) {
        if (initIncluded == false) {
            return scan(init, accumulator);
        }

        final CharIteratorEx iter = iteratorEx();

        return newStream(new CharIteratorEx() {
            private boolean isFirst = true;
            private char res = init;

            @Override
            public boolean hasNext() {
                return isFirst || iter.hasNext();
            }

            @Override
            public char nextChar() {
                if (isFirst) {
                    isFirst = false;
                    return init;
                }

                return (res = accumulator.applyAsChar(res, iter.nextChar()));
            }
        }, false);
    }

    @Override
    public CharStream intersection(final Collection c) {
        final Multiset multiset = Multiset.from(c);

        return newStream(this.sequential().filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                return multiset.getAndRemove(value) > 0;
            }
        }).iteratorEx(), sorted);
    }

    @Override
    public CharStream difference(final Collection c) {
        final Multiset multiset = Multiset.from(c);

        return newStream(this.sequential().filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                return multiset.getAndRemove(value) < 1;
            }
        }).iteratorEx(), sorted);
    }

    @Override
    public CharStream symmetricDifference(final Collection c) {
        final Multiset multiset = Multiset.from(c);

        return newStream(this.sequential().filter(new CharPredicate() {
            @Override
            public boolean test(char value) {
                return multiset.getAndRemove(value) < 1;
            }
        }).append(Stream.of(c).filter(new Predicate() {
            @Override
            public boolean test(Character value) {
                return multiset.getAndRemove(value) > 0;
            }
        }).mapToChar(ToCharFunction.UNBOX)).iteratorEx(), false);
    }

    @Override
    public CharStream reversed() {
        return newStream(new CharIteratorEx() {
            private boolean initialized = false;
            private char[] aar;
            private int cursor;

            @Override
            public boolean hasNext() {
                if (initialized == false) {
                    init();
                }

                return cursor > 0;
            }

            @Override
            public char nextChar() {
                if (initialized == false) {
                    init();
                }

                if (cursor <= 0) {
                    throw new NoSuchElementException();
                }

                return aar[--cursor];
            }

            @Override
            public long count() {
                if (initialized == false) {
                    init();
                }

                return cursor;
            }

            @Override
            public void skip(long n) {
                if (initialized == false) {
                    init();
                }

                cursor = n < cursor ? cursor - (int) n : 0;
            }

            @Override
            public char[] toArray() {
                if (initialized == false) {
                    init();
                }

                final char[] a = new char[cursor];

                for (int i = 0; i < cursor; i++) {
                    a[i] = aar[cursor - i - 1];
                }

                return a;
            }

            private void init() {
                if (initialized == false) {
                    initialized = true;
                    aar = AbstractCharStream.this.toArray();
                    cursor = aar.length;
                }
            }
        }, false);
    }

    @Override
    public CharStream shuffled(final Random rnd) {
        return lazyLoad(new Function() {
            @Override
            public char[] apply(final char[] a) {
                N.shuffle(a, rnd);
                return a;
            }
        }, false);
    }

    @Override
    public CharStream rotated(final int distance) {
        return newStream(new CharIteratorEx() {
            private boolean initialized = false;
            private char[] aar;
            private int len;
            private int start;
            private int cnt = 0;

            @Override
            public boolean hasNext() {
                if (initialized == false) {
                    init();
                }

                return cnt < len;
            }

            @Override
            public char nextChar() {
                if (hasNext() == false) {
                    throw new NoSuchElementException();
                }

                return aar[(start + cnt++) % len];
            }

            @Override
            public long count() {
                if (initialized == false) {
                    init();
                }

                return len - cnt;
            }

            @Override
            public void skip(long n) {
                if (initialized == false) {
                    init();
                }

                cnt = n < len - cnt ? cnt + (int) n : len;
            }

            @Override
            public char[] toArray() {
                if (initialized == false) {
                    init();
                }

                final char[] a = new char[len - cnt];

                for (int i = cnt; i < len; i++) {
                    a[i - cnt] = aar[(start + i) % len];
                }

                return a;
            }

            private void init() {
                if (initialized == false) {
                    initialized = true;
                    aar = AbstractCharStream.this.toArray();
                    len = aar.length;

                    if (len > 0) {
                        start = distance % len;

                        if (start < 0) {
                            start += len;
                        }

                        start = len - start;
                    }
                }
            }
        }, distance == 0 && sorted);
    }

    @Override
    public CharStream sorted() {
        if (sorted) {
            return newStream(iterator(), sorted);
        }

        return lazyLoad(new Function() {
            @Override
            public char[] apply(final char[] a) {
                if (isParallel()) {
                    N.parallelSort(a);
                } else {
                    N.sort(a);
                }

                return a;
            }
        }, true);
    }

    @Override
    public CharStream reverseSorted() {
        return newStream(new CharIteratorEx() {
            private boolean initialized = false;
            private char[] aar;
            private int cursor;

            @Override
            public boolean hasNext() {
                if (initialized == false) {
                    init();
                }

                return cursor > 0;
            }

            @Override
            public char nextChar() {
                if (initialized == false) {
                    init();
                }

                if (cursor <= 0) {
                    throw new NoSuchElementException();
                }

                return aar[--cursor];
            }

            @Override
            public long count() {
                if (initialized == false) {
                    init();
                }

                return cursor;
            }

            @Override
            public void skip(long n) {
                if (initialized == false) {
                    init();
                }

                cursor = n < cursor ? cursor - (int) n : 0;
            }

            @Override
            public char[] toArray() {
                if (initialized == false) {
                    init();
                }

                final char[] a = new char[cursor];

                for (int i = 0; i < cursor; i++) {
                    a[i] = aar[cursor - i - 1];
                }

                return a;
            }

            private void init() {
                if (initialized == false) {
                    initialized = true;
                    aar = AbstractCharStream.this.toArray();

                    if (isParallel()) {
                        N.parallelSort(aar);
                    } else {
                        N.sort(aar);
                    }

                    cursor = aar.length;
                }
            }
        }, false);
    }

    private CharStream lazyLoad(final Function op, final boolean sorted) {
        return newStream(new CharIteratorEx() {
            private boolean initialized = false;
            private char[] aar;
            private int cursor = 0;
            private int len;

            @Override
            public boolean hasNext() {
                if (initialized == false) {
                    init();
                }

                return cursor < len;
            }

            @Override
            public char nextChar() {
                if (initialized == false) {
                    init();
                }

                if (cursor >= len) {
                    throw new NoSuchElementException();
                }

                return aar[cursor++];
            }

            @Override
            public long count() {
                if (initialized == false) {
                    init();
                }

                return len - cursor;
            }

            @Override
            public void skip(long n) {
                if (initialized == false) {
                    init();
                }

                cursor = n > len - cursor ? len : cursor + (int) n;
            }

            @Override
            public char[] toArray() {
                if (initialized == false) {
                    init();
                }

                final char[] a = new char[len - cursor];

                for (int i = cursor; i < len; i++) {
                    a[i - cursor] = aar[i];
                }

                return a;
            }

            private void init() {
                if (initialized == false) {
                    initialized = true;
                    aar = op.apply(AbstractCharStream.this.toArray());
                    len = aar.length;
                }
            }
        }, sorted);
    }

    @Override
    public Stream indexed() {
        final MutableLong idx = MutableLong.of(0);

        return newStream(this.sequential().mapToObj(new CharFunction() {
            @Override
            public IndexedChar apply(char t) {
                return IndexedChar.of(t, idx.getAndIncrement());
            }
        }).iterator(), true, INDEXED_CHAR_COMPARATOR);
    }

    @Override
    public CharStream append(CharStream stream) {
        return CharStream.concat(this, stream);
    }

    @Override
    public CharStream prepend(CharStream stream) {
        return CharStream.concat(stream, this);
    }

    @Override
    public CharStream merge(CharStream b, CharBiFunction nextSelector) {
        return CharStream.merge(this, b, nextSelector);
    }

    @Override
    public CharStream zipWith(CharStream b, CharBinaryOperator zipFunction) {
        return CharStream.zip(this, b, zipFunction);
    }

    @Override
    public CharStream zipWith(CharStream b, CharStream c, CharTernaryOperator zipFunction) {
        return CharStream.zip(this, b, c, zipFunction);
    }

    @Override
    public CharStream zipWith(CharStream b, char valueForNoneA, char valueForNoneB, CharBinaryOperator zipFunction) {
        return CharStream.zip(this, b, valueForNoneA, valueForNoneB, zipFunction);
    }

    @Override
    public CharStream zipWith(CharStream b, CharStream c, char valueForNoneA, char valueForNoneB, char valueForNoneC, CharTernaryOperator zipFunction) {
        return CharStream.zip(this, b, c, valueForNoneA, valueForNoneB, valueForNoneC, zipFunction);
    }

    //    @Override
    //    public CharStream cached() {
    //        return newStream(toArray(), sorted);
    //    }

    @Override
    public  Map toMap(CharFunction keyMapper, CharFunction valueMapper) {
        return toMap(keyMapper, valueMapper, Suppliers. ofMap());
    }

    @Override
    public > M toMap(CharFunction keyMapper, CharFunction valueMapper, Supplier mapFactory) {
        return toMap(keyMapper, valueMapper, Fn. throwingMerger(), mapFactory);
    }

    @Override
    public  Map toMap(CharFunction keyMapper, CharFunction valueMapper, BinaryOperator mergeFunction) {
        return toMap(keyMapper, valueMapper, mergeFunction, Suppliers. ofMap());
    }

    @Override
    public  Map toMap(CharFunction keyMapper, Collector downstream) {
        return toMap(keyMapper, downstream, Suppliers. ofMap());
    }

    @Override
    public CharMatrix toMatrix() {
        return CharMatrix.of(toArray());
    }

    @Override
    public OptionalChar first() {
        assertNotClosed();

        try {
            final CharIterator iter = this.iteratorEx();

            return iter.hasNext() ? OptionalChar.of(iter.nextChar()) : OptionalChar.empty();
        } finally {
            close();
        }
    }

    @Override
    public OptionalChar last() {
        assertNotClosed();

        try {
            final CharIterator iter = this.iteratorEx();

            if (iter.hasNext() == false) {
                return OptionalChar.empty();
            }

            char next = iter.nextChar();

            while (iter.hasNext()) {
                next = iter.nextChar();
            }

            return OptionalChar.of(next);
        } finally {
            close();
        }
    }

    @Override
    public OptionalChar onlyOne() throws DuplicatedResultException {
        assertNotClosed();

        try {
            final CharIterator iter = this.iteratorEx();

            final OptionalChar result = iter.hasNext() ? OptionalChar.of(iter.nextChar()) : OptionalChar.empty();

            if (result.isPresent() && iter.hasNext()) {
                throw new DuplicatedResultException("There are at least two elements: " + Strings.concat(result.get(), ", ", iter.nextChar()));
            }

            return result;
        } finally {
            close();
        }
    }

    @Override
    public  OptionalChar findAny(final Try.CharPredicate predicate) throws E {
        return findFirst(predicate);
    }

    @Override
    public  OptionalChar findFirstOrLast(Try.CharPredicate predicateForFirst,
            Try.CharPredicate predicateForLast) throws E, E2 {
        assertNotClosed();

        try {
            final CharIteratorEx iter = iteratorEx();
            MutableChar last = null;
            char next = 0;

            while (iter.hasNext()) {
                next = iter.nextChar();

                if (predicateForFirst.test(next)) {
                    return OptionalChar.of(next);
                } else if (predicateForLast.test(next)) {
                    if (last == null) {
                        last = MutableChar.of(next);
                    } else {
                        last.setValue(next);
                    }
                }
            }

            return last == null ? OptionalChar.empty() : OptionalChar.of(last.value());
        } finally {
            close();
        }
    }

    @Override
    public Optional> percentiles() {
        assertNotClosed();

        try {
            final char[] a = sorted().toArray();

            if (a.length == 0) {
                return Optional.empty();
            }

            return Optional.of(N.percentiles(a));
        } finally {
            close();
        }
    }

    @Override
    public Pair>> summarizeAndPercentiles() {
        assertNotClosed();

        try {
            final char[] a = sorted().toArray();

            if (N.isNullOrEmpty(a)) {
                return Pair.of(new CharSummaryStatistics(), Optional.> empty());
            } else {
                return Pair.of(new CharSummaryStatistics(a.length, sum(a), a[0], a[a.length - 1]), Optional.of(N.percentiles(a)));
            }
        } finally {
            close();
        }
    }

    @Override
    public String join(final CharSequence delimiter, final CharSequence prefix, final CharSequence suffix) {
        assertNotClosed();

        try {
            final Joiner joiner = Joiner.with(delimiter, prefix, suffix).reuseCachedBuffer(true);
            final CharIteratorEx iter = this.iteratorEx();

            while (iter.hasNext()) {
                joiner.append(iter.nextChar());
            }

            return joiner.toString();
        } finally {
            close();
        }
    }

    @Override
    public  R collect(Supplier supplier, ObjCharConsumer accumulator) {
        final BiConsumer combiner = collectingCombiner;

        return collect(supplier, accumulator, combiner);
    }
}