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A general programming library in Java
/*
* Copyright (c) 2017, 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;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import com.landawn.abacus.util.function.BiFunction;
import com.landawn.abacus.util.function.BooleanSupplier;
import com.landawn.abacus.util.function.Function;
import com.landawn.abacus.util.function.Predicate;
import com.landawn.abacus.util.function.Supplier;
import com.landawn.abacus.util.function.TriFunction;
/**
*
*
* @since 0.9
*
* @author Haiyang Li
*/
public final class Iterators {
private Iterators() {
// singleton.
}
public static List toList(final Iterator iter) {
if (iter == null) {
return new ArrayList<>();
}
final List result = new ArrayList<>();
while (iter.hasNext()) {
result.add(iter.next());
}
return result;
}
public static Set toSet(final Iterator iter) {
if (iter == null) {
return new HashSet<>();
}
final Set result = new HashSet<>();
while (iter.hasNext()) {
result.add(iter.next());
}
return result;
}
public static > C toCollection(final Iterator iter, final Supplier collectionFactory) {
final C c = collectionFactory.get();
if (iter == null) {
return c;
}
while (iter.hasNext()) {
c.add(iter.next());
}
return c;
}
public static Map toMap(final Iterator iter, final Try.Function keyExtractor) throws E {
N.requireNonNull(keyExtractor);
if (iter == null) {
return new HashMap<>();
}
final Map result = new HashMap<>();
T next = null;
while (iter.hasNext()) {
next = iter.next();
result.put(keyExtractor.apply(next), next);
}
return result;
}
public static Map toMap(final Iterator iter,
final Try.Function keyExtractor, final Try.Function valueExtractor) throws E, E2 {
N.requireNonNull(keyExtractor);
N.requireNonNull(valueExtractor);
if (iter == null) {
return new HashMap<>();
}
final Map result = new HashMap<>();
T next = null;
while (iter.hasNext()) {
next = iter.next();
result.put(keyExtractor.apply(next), valueExtractor.apply(next));
}
return result;
}
public static , E extends Exception, E2 extends Exception> M toMap(final Iterator iter,
final Try.Function keyExtractor, final Try.Function valueExtractor, final Supplier mapSupplier)
throws E, E2 {
N.requireNonNull(keyExtractor);
N.requireNonNull(valueExtractor);
if (iter == null) {
return mapSupplier.get();
}
final M result = mapSupplier.get();
T next = null;
while (iter.hasNext()) {
next = iter.next();
result.put(keyExtractor.apply(next), valueExtractor.apply(next));
}
return result;
}
public static ObjIterator repeat(final T e, final int n) {
N.checkArgument(n >= 0, "'n' can't be negative: %s", n);
if (n == 0) {
return ObjIterator.empty();
}
return new ObjIterator() {
private int cnt = n;
@Override
public boolean hasNext() {
return cnt > 0;
}
@Override
public T next() {
if (cnt <= 0) {
throw new NoSuchElementException();
}
cnt--;
return e;
}
};
};
public static ObjIterator repeatt(final Collection c, final int n) {
N.checkArgument(n >= 0, "'n' can't be negative: %s", n);
if (n == 0 || N.isNullOrEmpty(c)) {
return ObjIterator.empty();
}
return new ObjIterator() {
private Iterator iter = null;
private int cnt = n;
@Override
public boolean hasNext() {
return cnt > 0 || (iter != null && iter.hasNext());
}
@Override
public T next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
if (iter == null || iter.hasNext() == false) {
iter = c.iterator();
cnt--;
}
return iter.next();
}
};
};
public static ObjIterator repeatToSize(final Collection c, final int size) {
N.checkArgument(size >= 0, "'size' can't be negative: %s", size);
N.checkArgument(size == 0 || N.notNullOrEmpty(c), "Collection can't be empty or null when size > 0");
if (N.isNullOrEmpty(c) || size == 0) {
return ObjIterator.empty();
}
return new ObjIterator() {
private Iterator iter = null;
private int cnt = size;
@Override
public boolean hasNext() {
return cnt > 0;
}
@Override
public T next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
if (iter == null || iter.hasNext() == false) {
iter = c.iterator();
}
cnt--;
return iter.next();
}
};
};
public static ObjIterator nRepeat(final Collection c, final int n) {
N.checkArgument(n >= 0, "'n' can't be negative: %s", n);
if (n == 0 || N.isNullOrEmpty(c)) {
return ObjIterator.empty();
}
return new ObjIterator() {
private Iterator iter = null;
private T next = null;
private int cnt = n;
@Override
public boolean hasNext() {
return cnt > 0 || (iter != null && iter.hasNext());
}
@Override
public T next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
if (iter == null) {
iter = c.iterator();
next = iter.next();
} else if (cnt <= 0) {
next = iter.next();
cnt = n;
}
cnt--;
return next;
}
};
};
public static ObjIterator nRepeatToSize(final Collection c, final int size) {
N.checkArgument(size >= 0, "'size' can't be negative: %s", size);
N.checkArgument(size == 0 || N.notNullOrEmpty(c), "Collection can't be empty or null when size > 0");
if (N.isNullOrEmpty(c) || size == 0) {
return ObjIterator.empty();
}
return new ObjIterator() {
private final int n = size / c.size();
private int mod = size % c.size();
private Iterator iter = null;
private T next = null;
private int cnt = mod-- > 0 ? n + 1 : n;
@Override
public boolean hasNext() {
return cnt > 0 || ((n > 0 || mod > 0) && (iter != null && iter.hasNext()));
}
@Override
public T next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
if (iter == null) {
iter = c.iterator();
next = iter.next();
} else if (cnt <= 0) {
next = iter.next();
cnt = mod-- > 0 ? n + 1 : n;
}
cnt--;
return next;
}
};
};
@SafeVarargs
public static BooleanIterator concat(final boolean[]... a) {
if (N.isNullOrEmpty(a)) {
return BooleanIterator.EMPTY;
}
return new BooleanIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private boolean[] 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 boolean nextBoolean() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static ShortIterator concat(final short[]... a) {
if (N.isNullOrEmpty(a)) {
return ShortIterator.EMPTY;
}
return new ShortIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private short[] 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 short nextShort() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static ByteIterator concat(final byte[]... a) {
if (N.isNullOrEmpty(a)) {
return ByteIterator.EMPTY;
}
return new ByteIterator() {
private final Iterator iter = Arrays.asList(a).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() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static IntIterator concat(final int[]... a) {
if (N.isNullOrEmpty(a)) {
return IntIterator.EMPTY;
}
return new IntIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private int[] 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 int nextInt() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static LongIterator concat(final long[]... a) {
if (N.isNullOrEmpty(a)) {
return LongIterator.EMPTY;
}
return new LongIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private long[] 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 long nextLong() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static FloatIterator concat(final float[]... a) {
if (N.isNullOrEmpty(a)) {
return FloatIterator.EMPTY;
}
return new FloatIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private float[] 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 float nextFloat() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static DoubleIterator concat(final double[]... a) {
if (N.isNullOrEmpty(a)) {
return DoubleIterator.EMPTY;
}
return new DoubleIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private double[] 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 double nextDouble() {
if ((cur == null || cursor >= cur.length) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur[cursor++];
}
};
}
@SafeVarargs
public static BooleanIterator concat(final BooleanIterator... a) {
if (N.isNullOrEmpty(a)) {
return BooleanIterator.EMPTY;
}
return new BooleanIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private BooleanIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public boolean nextBoolean() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextBoolean();
}
};
}
@SafeVarargs
public static CharIterator concat(final CharIterator... a) {
if (N.isNullOrEmpty(a)) {
return CharIterator.EMPTY;
}
return new CharIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private CharIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public char nextChar() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextChar();
}
};
}
@SafeVarargs
public static ByteIterator concat(final ByteIterator... a) {
if (N.isNullOrEmpty(a)) {
return ByteIterator.EMPTY;
}
return new ByteIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private ByteIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public byte nextByte() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextByte();
}
};
}
@SafeVarargs
public static ShortIterator concat(final ShortIterator... a) {
if (N.isNullOrEmpty(a)) {
return ShortIterator.EMPTY;
}
return new ShortIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private ShortIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public short nextShort() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextShort();
}
};
}
@SafeVarargs
public static IntIterator concat(final IntIterator... a) {
if (N.isNullOrEmpty(a)) {
return IntIterator.EMPTY;
}
return new IntIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private IntIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public int nextInt() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextInt();
}
};
}
@SafeVarargs
public static LongIterator concat(final LongIterator... a) {
if (N.isNullOrEmpty(a)) {
return LongIterator.EMPTY;
}
return new LongIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private LongIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public long nextLong() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextLong();
}
};
}
@SafeVarargs
public static FloatIterator concat(final FloatIterator... a) {
if (N.isNullOrEmpty(a)) {
return FloatIterator.EMPTY;
}
return new FloatIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private FloatIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public float nextFloat() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextFloat();
}
};
}
@SafeVarargs
public static DoubleIterator concat(final DoubleIterator... a) {
if (N.isNullOrEmpty(a)) {
return DoubleIterator.EMPTY;
}
return new DoubleIterator() {
private final Iterator iter = Arrays.asList(a).iterator();
private DoubleIterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public double nextDouble() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.nextDouble();
}
};
}
@SafeVarargs
public static ObjIterator concat(final T[]... a) {
if (N.isNullOrEmpty(a)) {
return ObjIterator.empty();
}
final List> list = new ArrayList<>(a.length);
for (T[] e : a) {
if (N.notNullOrEmpty(e)) {
list.add(ObjIterator.of(e));
}
}
return concat(list);
}
@SafeVarargs
public static ObjIterator concat(final Collection... a) {
if (N.isNullOrEmpty(a)) {
return ObjIterator.empty();
}
final List> list = new ArrayList<>(a.length);
for (Collection e : a) {
if (N.notNullOrEmpty(e)) {
list.add(e.iterator());
}
}
return concat(list);
}
@SafeVarargs
public static ObjIterator concat(final Iterator... a) {
if (N.isNullOrEmpty(a)) {
return ObjIterator.empty();
}
return concat(N.asList(a));
}
public static ObjIterator concat(final Collection> c) {
if (N.isNullOrEmpty(c)) {
return ObjIterator.empty();
}
return new ObjIterator() {
private final Iterator> iter = c.iterator();
private Iterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
cur = iter.next();
}
return cur != null && cur.hasNext();
}
@Override
public T next() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.next();
}
};
}
public static ObjIterator concatt(final Collection> c) {
if (N.isNullOrEmpty(c)) {
return ObjIterator.empty();
}
return new ObjIterator() {
private final Iterator> iter = c.iterator();
private Iterator cur;
@Override
public boolean hasNext() {
while ((cur == null || cur.hasNext() == false) && iter.hasNext()) {
final Collection c = iter.next();
cur = N.isNullOrEmpty(c) ? null : c.iterator();
}
return cur != null && cur.hasNext();
}
@Override
public T next() {
if ((cur == null || cur.hasNext() == false) && hasNext() == false) {
throw new NoSuchElementException();
}
return cur.next();
}
};
}
public static ObjIterator merge(final Collection a, final Collection b,
final BiFunction nextSelector) {
final Iterator iterA = N.isNullOrEmpty(a) ? ObjIterator. empty() : (Iterator) a.iterator();
final Iterator iterB = N.isNullOrEmpty(b) ? ObjIterator. empty() : (Iterator) b.iterator();
return merge(iterA, iterB, nextSelector);
}
public static ObjIterator merge(final Iterator a, final Iterator b,
final BiFunction nextSelector) {
N.requireNonNull(nextSelector);
return new ObjIterator() {
private final Iterator iterA = a == null ? ObjIterator. empty() : a;
private final Iterator iterB = b == null ? ObjIterator. empty() : b;
private T nextA = null;
private T nextB = null;
private boolean hasNextA = false;
private boolean hasNextB = false;
@Override
public boolean hasNext() {
return hasNextA || hasNextB || iterA.hasNext() || iterB.hasNext();
}
@Override
public T next() {
if (hasNextA) {
if (iterB.hasNext()) {
if (nextSelector.apply(nextA, (nextB = iterB.next())) == Nth.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.next()), nextB) == Nth.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.next()), (nextB = iterB.next())) == Nth.FIRST) {
hasNextB = true;
return nextA;
} else {
hasNextA = true;
return nextB;
}
} else {
return iterA.next();
}
} else {
return iterB.next();
}
}
};
}
public static ObjIterator zip(final Collection a, final Collection b, final BiFunction zipFunction) {
final Iterator iterA = N.isNullOrEmpty(a) ? ObjIterator. empty() : a.iterator();
final Iterator iterB = N.isNullOrEmpty(b) ? ObjIterator. empty() : b.iterator();
return zip(iterA, iterB, zipFunction);
}
public static ObjIterator zip(final Iterator a, final Iterator b, final BiFunction zipFunction) {
N.requireNonNull(zipFunction);
return new ObjIterator() {
private final Iterator iterA = a == null ? ObjIterator. empty() : a;
private final Iterator iterB = b == null ? ObjIterator. empty() : b;
@Override
public boolean hasNext() {
return iterA.hasNext() && iterB.hasNext();
}
@Override
public R next() {
return zipFunction.apply(iterA.next(), iterB.next());
}
};
}
public static ObjIterator zip(final Collection a, final Collection b, final Collection c,
final TriFunction zipFunction) {
final Iterator iterA = N.isNullOrEmpty(a) ? ObjIterator. empty() : a.iterator();
final Iterator iterB = N.isNullOrEmpty(b) ? ObjIterator. empty() : b.iterator();
final Iterator iterC = N.isNullOrEmpty(c) ? ObjIterator. empty() : c.iterator();
return zip(iterA, iterB, iterC, zipFunction);
}
public static ObjIterator zip(final Iterator a, final Iterator b, final Iterator c,
final TriFunction zipFunction) {
N.requireNonNull(zipFunction);
return new ObjIterator() {
private final Iterator iterA = a == null ? ObjIterator. empty() : a;
private final Iterator iterB = b == null ? ObjIterator. empty() : b;
private final Iterator iterC = c == null ? ObjIterator. empty() : c;
@Override
public boolean hasNext() {
return iterA.hasNext() && iterB.hasNext() && iterC.hasNext();
}
@Override
public R next() {
return zipFunction.apply(iterA.next(), iterB.next(), iterC.next());
}
};
}
public static ObjIterator zip(final Collection a, final Collection b, final A valueForNoneA, final B valueForNoneB,
final BiFunction zipFunction) {
final Iterator iterA = N.isNullOrEmpty(a) ? ObjIterator. empty() : a.iterator();
final Iterator iterB = N.isNullOrEmpty(b) ? ObjIterator. empty() : b.iterator();
return zip(iterA, iterB, valueForNoneA, valueForNoneB, zipFunction);
}
public static ObjIterator zip(final Iterator a, final Iterator b, final A valueForNoneA, final B valueForNoneB,
final BiFunction zipFunction) {
N.requireNonNull(zipFunction);
return new ObjIterator() {
private final Iterator iterA = a == null ? ObjIterator. empty() : a;
private final Iterator iterB = b == null ? ObjIterator. empty() : b;
@Override
public boolean hasNext() {
return iterA.hasNext() || iterB.hasNext();
}
@Override
public R next() {
return zipFunction.apply(iterA.hasNext() ? iterA.next() : valueForNoneA, iterB.hasNext() ? iterB.next() : valueForNoneB);
}
};
}
public static ObjIterator zip(final Collection a, final Collection b, final Collection c, final A valueForNoneA,
final B valueForNoneB, final C valueForNoneC, final TriFunction zipFunction) {
final Iterator iterA = N.isNullOrEmpty(a) ? ObjIterator. empty() : a.iterator();
final Iterator iterB = N.isNullOrEmpty(b) ? ObjIterator. empty() : b.iterator();
final Iterator iterC = N.isNullOrEmpty(c) ? ObjIterator. empty() : c.iterator();
return zip(iterA, iterB, iterC, valueForNoneA, valueForNoneB, valueForNoneC, zipFunction);
}
public static ObjIterator zip(final Iterator a, final Iterator b, final Iterator c, final A valueForNoneA, final B valueForNoneB,
final C valueForNoneC, final TriFunction zipFunction) {
return new ObjIterator() {
private final Iterator iterA = a == null ? ObjIterator. empty() : a;
private final Iterator iterB = b == null ? ObjIterator. empty() : b;
private final Iterator iterC = c == null ? ObjIterator. empty() : c;
@Override
public boolean hasNext() {
return iterA.hasNext() || iterB.hasNext() || iterC.hasNext();
}
@Override
public R next() {
return zipFunction.apply(iterA.hasNext() ? iterA.next() : valueForNoneA, iterB.hasNext() ? iterB.next() : valueForNoneB,
iterC.hasNext() ? iterC.next() : valueForNoneC);
}
};
}
/**
*
* @param iter
* @param unzip the second parameter is an output parameter.
* @return
*/
public static Pair, List> unzip(final Iterator iter,
final Try.BiConsumer, E> unzip) throws E {
final List l = new ArrayList();
final List r = new ArrayList();
final Pair p = new Pair<>();
if (iter != null) {
while (iter.hasNext()) {
unzip.accept(iter.next(), p);
l.add(p.left);
r.add(p.right);
}
}
return Pair.of(l, r);
}
/**
*
* @param iter
* @param unzip the second parameter is an output parameter.
* @param supplier
* @return
*/
public static , RC extends Collection, E extends Exception> Pair unzip(final Iterator iter,
final Try.BiConsumer, E> unzip, final Supplier> supplier) throws E {
final LC l = (LC) supplier.get();
final RC r = (RC) supplier.get();
final Pair p = new Pair<>();
if (iter != null) {
while (iter.hasNext()) {
unzip.accept(iter.next(), p);
l.add(p.left);
r.add(p.right);
}
}
return Pair.of(l, r);
}
/**
*
* @param iter
* @param unzip the second parameter is an output parameter.
* @return
*/
public static Triple, List, List> unzipp(final Iterator iter,
final Try.BiConsumer, E> unzip) throws E {
final List l = new ArrayList();
final List m = new ArrayList();
final List r = new ArrayList();
final Triple t = new Triple<>();
if (iter != null) {
while (iter.hasNext()) {
unzip.accept(iter.next(), t);
l.add(t.left);
m.add(t.middle);
r.add(t.right);
}
}
return Triple.of(l, m, r);
}
/**
*
* @param iter
* @param unzip the second parameter is an output parameter.
* @param supplier
* @return
*/
public static , MC extends Collection, RC extends Collection, E extends Exception> Triple unzipp(
final Iterator iter, final Try.BiConsumer, E> unzip, final Supplier> supplier)
throws E {
final LC l = (LC) supplier.get();
final MC m = (MC) supplier.get();
final RC r = (RC) supplier.get();
final Triple t = new Triple<>();
if (iter != null) {
while (iter.hasNext()) {
unzip.accept(iter.next(), t);
l.add(t.left);
m.add(t.middle);
r.add(t.right);
}
}
return Triple.of(l, m, r);
}
public static ObjIterator> split(final Iterator iter, final int size) {
N.checkArgument(size > 0, "'size' must be greater than 0, can't be: %s", size);
if (iter == null) {
return ObjIterator.empty();
}
return new ObjIterator>() {
private final Iterator iterator = iter;
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Override
public List next() {
if (hasNext() == false) {
throw new NoSuchElementException();
}
final List next = new ArrayList<>(size);
for (int i = 0; i < size && iterator.hasNext(); i++) {
next.add(iterator.next());
}
return next;
}
};
}
public static Nullable first(final Iterator iter) {
return iter != null && iter.hasNext() ? Nullable.of(iter.next()) : Nullable. empty();
}
public static Optional firstNonNull(final Iterator iter) {
if (iter == null) {
return Optional.empty();
}
T next = null;
while (iter.hasNext()) {
if ((next = iter.next()) != null) {
return Optional.of(next);
}
}
return Optional.empty();
}
public static Nullable last(final Iterator iter) {
if (iter == null || iter.hasNext() == false) {
return Nullable.empty();
}
T next = null;
while (iter.hasNext()) {
next = iter.next();
}
return Nullable.of(next);
}
public static Optional lastNonNull(final Iterator iter) {
if (iter == null) {
return Optional.empty();
}
T next = null;
T lastNonNull = null;
while (iter.hasNext()) {
if ((next = iter.next()) != null) {
lastNonNull = next;
}
}
return Optional.ofNullable(lastNonNull);
}
public static ObjIterator skipNull(final Iterator iter) {
if (iter == null) {
return ObjIterator.empty();
}
return new ObjIterator() {
private final Iterator iterator = iter;
private T next;
@Override
public boolean hasNext() {
if (next == null && iterator.hasNext()) {
next = iterator.next();
if (next == null) {
while (iterator.hasNext()) {
next = iterator.next();
if (next != null) {
break;
}
}
}
}
return next != null;
}
@Override
public T next() {
if (next == null && hasNext() == false) {
throw new NoSuchElementException();
}
final T result = next;
next = null;
return result;
}
};
}
public static ImmutableIterator generate(final BooleanSupplier hasNext, final Supplier next) {
return new ImmutableIterator() {
@Override
public boolean hasNext() {
return hasNext.getAsBoolean();
}
@Override
public T next() {
return next.get();
}
};
}
public static ImmutableIterator generate(final U seed, final Predicate hasNext, final Function next) {
return new ImmutableIterator() {
@Override
public boolean hasNext() {
return hasNext.test(seed);
}
@Override
public T next() {
return next.apply(seed);
}
};
}
}
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