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/*
* Copyright (C) 2002-2022 Sebastiano Vigna
*
* 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 it.unimi.dsi.fastutil.ints;
import static it.unimi.dsi.fastutil.BigArrays.grow;
import static it.unimi.dsi.fastutil.BigArrays.length;
import static it.unimi.dsi.fastutil.BigArrays.set;
import static it.unimi.dsi.fastutil.BigArrays.trim;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.PrimitiveIterator;
/**
* A class providing static methods and objects that do useful things with type-specific iterators.
*
* @see Iterator
*/
public final class IntIterators {
private IntIterators() {
}
/**
* A class returning no elements and a type-specific iterator interface.
*
*
* This class may be useful to implement your own in case you subclass a type-specific iterator.
*/
public static class EmptyIterator implements IntListIterator, java.io.Serializable, Cloneable {
private static final long serialVersionUID = -7046029254386353129L;
protected EmptyIterator() {
}
@Override
public boolean hasNext() {
return false;
}
@Override
public boolean hasPrevious() {
return false;
}
@Override
public int nextInt() {
throw new NoSuchElementException();
}
@Override
public int previousInt() {
throw new NoSuchElementException();
}
@Override
public int nextIndex() {
return 0;
}
@Override
public int previousIndex() {
return -1;
}
@Override
public int skip(int n) {
return 0;
}
@Override
public int back(int n) {
return 0;
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
}
@Override
public Object clone() {
return EMPTY_ITERATOR;
}
private Object readResolve() {
return EMPTY_ITERATOR;
}
}
/**
* An empty iterator. It is serializable and cloneable.
*
*
* The class of this objects represent an abstract empty iterator that can iterate as a
* type-specific (list) iterator.
*/
public static final EmptyIterator EMPTY_ITERATOR = new EmptyIterator();
/** An iterator returning a single element. */
private static class SingletonIterator implements IntListIterator {
private final int element;
private byte curr;
public SingletonIterator(final int element) {
this.element = element;
}
@Override
public boolean hasNext() {
return curr == 0;
}
@Override
public boolean hasPrevious() {
return curr == 1;
}
@Override
public int nextInt() {
if (!hasNext()) throw new NoSuchElementException();
curr = 1;
return element;
}
@Override
public int previousInt() {
if (!hasPrevious()) throw new NoSuchElementException();
curr = 0;
return element;
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
if (curr == 0) {
action.accept(element);
curr = 1;
}
}
@Override
public int nextIndex() {
return curr;
}
@Override
public int previousIndex() {
return curr - 1;
}
@Override
public int back(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
if (n == 0 || curr < 1) return 0;
curr = 1;
return 1;
}
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
if (n == 0 || curr > 0) return 0;
curr = 0;
return 1;
}
}
/**
* Returns an immutable iterator that iterates just over the given element.
*
* @param element the only element to be returned by a type-specific list iterator.
* @return an immutable iterator that iterates just over {@code element}.
*/
public static IntListIterator singleton(final int element) {
return new SingletonIterator(element);
}
/** A class to wrap arrays in iterators. */
private static class ArrayIterator implements IntListIterator {
private final int[] array;
private final int offset, length;
private int curr;
public ArrayIterator(final int[] array, final int offset, final int length) {
this.array = array;
this.offset = offset;
this.length = length;
}
@Override
public boolean hasNext() {
return curr < length;
}
@Override
public boolean hasPrevious() {
return curr > 0;
}
@Override
public int nextInt() {
if (!hasNext()) throw new NoSuchElementException();
return array[offset + curr++];
}
@Override
public int previousInt() {
if (!hasPrevious()) throw new NoSuchElementException();
return array[offset + --curr];
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
for (; curr < length; ++curr) {
action.accept(array[offset + curr]);
}
}
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
if (n <= length - curr) {
curr += n;
return n;
}
n = length - curr;
curr = length;
return n;
}
@Override
public int back(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
if (n <= curr) {
curr -= n;
return n;
}
n = curr;
curr = 0;
return n;
}
@Override
public int nextIndex() {
return curr;
}
@Override
public int previousIndex() {
return curr - 1;
}
}
/**
* Wraps the given part of an array into a type-specific list iterator.
*
*
* The type-specific list iterator returned by this method will iterate {@code length} times,
* returning consecutive elements of the given array starting from the one with index
* {@code offset}.
*
* @param array an array to wrap into a type-specific list iterator.
* @param offset the first element of the array to be returned.
* @param length the number of elements to return.
* @return an iterator that will return {@code length} elements of {@code array} starting at
* position {@code offset}.
*/
public static IntListIterator wrap(final int[] array, final int offset, final int length) {
IntArrays.ensureOffsetLength(array, offset, length);
return new ArrayIterator(array, offset, length);
}
/**
* Wraps the given array into a type-specific list iterator.
*
*
* The type-specific list iterator returned by this method will return all elements of the given
* array.
*
* @param array an array to wrap into a type-specific list iterator.
* @return an iterator that will return the elements of {@code array}.
*/
public static IntListIterator wrap(final int[] array) {
return new ArrayIterator(array, 0, array.length);
}
/**
* Unwraps an iterator into an array starting at a given offset for a given number of elements.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned, up
* to a maximum of {@code length}, in the given array starting at {@code offset}. The number of
* actually unwrapped elements is returned (it may be less than {@code max} if the iterator emits
* less than {@code max} elements).
*
* @param i a type-specific iterator.
* @param array an array to contain the output of the iterator.
* @param offset the first element of the array to be returned.
* @param max the maximum number of elements to unwrap.
* @return the number of elements unwrapped.
*/
public static int unwrap(final IntIterator i, final int array[], int offset, final int max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
if (offset < 0 || offset + max > array.length) throw new IllegalArgumentException();
int j = max;
while (j-- != 0 && i.hasNext()) array[offset++] = i.nextInt();
return max - j - 1;
}
/**
* Unwraps an iterator into an array.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned in
* the given array. The iteration will stop when the iterator has no more elements or when the end
* of the array has been reached.
*
* @param i a type-specific iterator.
* @param array an array to contain the output of the iterator.
* @return the number of elements unwrapped.
*/
public static int unwrap(final IntIterator i, final int array[]) {
return unwrap(i, array, 0, array.length);
}
/**
* Unwraps an iterator, returning an array, with a limit on the number of elements.
*
*
* This method iterates over the given type-specific iterator and returns an array containing the
* elements returned by the iterator. At most {@code max} elements will be returned.
*
* @param i a type-specific iterator.
* @param max the maximum number of elements to be unwrapped.
* @return an array containing the elements returned by the iterator (at most {@code max}).
*/
public static int[] unwrap(final IntIterator i, int max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
int array[] = new int[16];
int j = 0;
while (max-- != 0 && i.hasNext()) {
if (j == array.length) array = IntArrays.grow(array, j + 1);
array[j++] = i.nextInt();
}
return IntArrays.trim(array, j);
}
/**
* Unwraps an iterator, returning an array.
*
*
* This method iterates over the given type-specific iterator and returns an array containing the
* elements returned by the iterator.
*
* @param i a type-specific iterator.
* @return an array containing the elements returned by the iterator.
*/
public static int[] unwrap(final IntIterator i) {
return unwrap(i, Integer.MAX_VALUE);
}
/**
* Unwraps an iterator into a big array starting at a given offset for a given number of elements.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned, up
* to a maximum of {@code length}, in the given big array starting at {@code offset}. The number of
* actually unwrapped elements is returned (it may be less than {@code max} if the iterator emits
* less than {@code max} elements).
*
* @param i a type-specific iterator.
* @param array a big array to contain the output of the iterator.
* @param offset the first element of the array to be returned.
* @param max the maximum number of elements to unwrap.
* @return the number of elements unwrapped.
*/
public static long unwrap(final IntIterator i, final int array[][], long offset, final long max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
if (offset < 0 || offset + max > length(array)) throw new IllegalArgumentException();
long j = max;
while (j-- != 0 && i.hasNext()) set(array, offset++, i.nextInt());
return max - j - 1;
}
/**
* Unwraps an iterator into a big array.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned in
* the given big array. The iteration will stop when the iterator has no more elements or when the
* end of the array has been reached.
*
* @param i a type-specific iterator.
* @param array a big array to contain the output of the iterator.
* @return the number of elements unwrapped.
*/
public static long unwrap(final IntIterator i, final int array[][]) {
return unwrap(i, array, 0, length(array));
}
/**
* Unwraps an iterator into a type-specific collection, with a limit on the number of elements.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned, up
* to a maximum of {@code max}, in the given type-specific collection. The number of actually
* unwrapped elements is returned (it may be less than {@code max} if the iterator emits less than
* {@code max} elements).
*
* @param i a type-specific iterator.
* @param c a type-specific collection array to contain the output of the iterator.
* @param max the maximum number of elements to unwrap.
* @return the number of elements unwrapped. Note that this is the number of elements returned by
* the iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates).
*/
public static int unwrap(final IntIterator i, final IntCollection c, final int max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
int j = max;
while (j-- != 0 && i.hasNext()) c.add(i.nextInt());
return max - j - 1;
}
/**
* Unwraps an iterator, returning a big array, with a limit on the number of elements.
*
*
* This method iterates over the given type-specific iterator and returns a big array containing the
* elements returned by the iterator. At most {@code max} elements will be returned.
*
* @param i a type-specific iterator.
* @param max the maximum number of elements to be unwrapped.
* @return a big array containing the elements returned by the iterator (at most {@code max}).
*/
public static int[][] unwrapBig(final IntIterator i, long max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
int array[][] = IntBigArrays.newBigArray(16);
long j = 0;
while (max-- != 0 && i.hasNext()) {
if (j == length(array)) array = grow(array, j + 1);
set(array, j++, i.nextInt());
}
return trim(array, j);
}
/**
* Unwraps an iterator, returning a big array.
*
*
* This method iterates over the given type-specific iterator and returns a big array containing the
* elements returned by the iterator.
*
* @param i a type-specific iterator.
* @return a big array containing the elements returned by the iterator.
*/
public static int[][] unwrapBig(final IntIterator i) {
return unwrapBig(i, Long.MAX_VALUE);
}
/**
* Unwraps an iterator into a type-specific collection.
*
*
* This method iterates over the given type-specific iterator and stores the elements returned in
* the given type-specific collection. The returned count on the number unwrapped elements is a
* long, so that it will work also with very large collections.
*
* @param i a type-specific iterator.
* @param c a type-specific collection to contain the output of the iterator.
* @return the number of elements unwrapped. Note that this is the number of elements returned by
* the iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates).
*/
public static long unwrap(final IntIterator i, final IntCollection c) {
long n = 0;
while (i.hasNext()) {
c.add(i.nextInt());
n++;
}
return n;
}
/**
* Pours an iterator into a type-specific collection, with a limit on the number of elements.
*
*
* This method iterates over the given type-specific iterator and adds the returned elements to the
* given collection (up to {@code max}).
*
* @param i a type-specific iterator.
* @param s a type-specific collection.
* @param max the maximum number of elements to be poured.
* @return the number of elements poured. Note that this is the number of elements returned by the
* iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates).
*/
public static int pour(final IntIterator i, final IntCollection s, final int max) {
if (max < 0) throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
int j = max;
while (j-- != 0 && i.hasNext()) s.add(i.nextInt());
return max - j - 1;
}
/**
* Pours an iterator into a type-specific collection.
*
*
* This method iterates over the given type-specific iterator and adds the returned elements to the
* given collection.
*
* @param i a type-specific iterator.
* @param s a type-specific collection.
* @return the number of elements poured. Note that this is the number of elements returned by the
* iterator, which is not necessarily the number of elements that have been added to the
* collection (because of duplicates).
*/
public static int pour(final IntIterator i, final IntCollection s) {
return pour(i, s, Integer.MAX_VALUE);
}
/**
* Pours an iterator, returning a type-specific list, with a limit on the number of elements.
*
*
* This method iterates over the given type-specific iterator and returns a type-specific list
* containing the returned elements (up to {@code max}). Iteration on the returned list is
* guaranteed to produce the elements in the same order in which they appeared in the iterator.
*
*
* @param i a type-specific iterator.
* @param max the maximum number of elements to be poured.
* @return a type-specific list containing the returned elements, up to {@code max}.
*/
public static IntList pour(final IntIterator i, int max) {
final IntArrayList l = new IntArrayList();
pour(i, l, max);
l.trim();
return l;
}
/**
* Pours an iterator, returning a type-specific list.
*
*
* This method iterates over the given type-specific iterator and returns a list containing the
* returned elements. Iteration on the returned list is guaranteed to produce the elements in the
* same order in which they appeared in the iterator.
*
* @param i a type-specific iterator.
* @return a type-specific list containing the returned elements.
*/
public static IntList pour(final IntIterator i) {
return pour(i, Integer.MAX_VALUE);
}
private static class IteratorWrapper implements IntIterator {
final Iterator i;
public IteratorWrapper(final Iterator i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public void remove() {
i.remove();
}
@Override
public int nextInt() {
return (i.next()).intValue();
}
// This is pretty much the only time overriding this overload is correct; we want to
// delegate as an Object consumer, not wrap it as a primitive one.
@Override
public void forEachRemaining(final IntConsumer action) {
i.forEachRemaining(action);
}
@SuppressWarnings("unchecked")
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
i.forEachRemaining(action instanceof Consumer ? (Consumer)action : action::accept);
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
i.forEachRemaining(action);
}
}
private static class PrimitiveIteratorWrapper implements IntIterator {
final PrimitiveIterator.OfInt i;
public PrimitiveIteratorWrapper(PrimitiveIterator.OfInt i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public void remove() {
i.remove();
}
@Override
public int nextInt() {
return i.nextInt();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
i.forEachRemaining(action);
}
}
/**
* Wraps a standard iterator into a type-specific iterator.
*
*
* This method wraps a standard iterator into a type-specific one which will handle the type
* conversions for you. Of course, any attempt to wrap an iterator returning the instances of the
* wrong class will generate a {@link ClassCastException}. The returned iterator is backed by
* {@code i}: changes to one of the iterators will affect the other, too.
*
* @implNote If {@code i} is already type-specific, it will returned and no new object will be
* generated.
*
* @param i an iterator.
* @return a type-specific iterator backed by {@code i}.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static IntIterator asIntIterator(final Iterator i) {
if (i instanceof IntIterator) return (IntIterator)i;
if (i instanceof PrimitiveIterator.OfInt) return new PrimitiveIteratorWrapper((PrimitiveIterator.OfInt)i);
return new IteratorWrapper(i);
}
private static class ListIteratorWrapper implements IntListIterator {
final ListIterator i;
public ListIteratorWrapper(final ListIterator i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public boolean hasPrevious() {
return i.hasPrevious();
}
@Override
public int nextIndex() {
return i.nextIndex();
}
@Override
public int previousIndex() {
return i.previousIndex();
}
@Override
public void set(int k) {
i.set(Integer.valueOf(k));
}
@Override
public void add(int k) {
i.add(Integer.valueOf(k));
}
@Override
public void remove() {
i.remove();
}
@Override
public int nextInt() {
return (i.next()).intValue();
}
@Override
public int previousInt() {
return (i.previous()).intValue();
}
// This is pretty much the only time overriding this overload is correct; we want to
// delegate as an Object consumer, not wrap it as a primitive one.
@Override
public void forEachRemaining(final IntConsumer action) {
i.forEachRemaining(action);
}
@SuppressWarnings("unchecked")
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
i.forEachRemaining(action instanceof Consumer ? (Consumer)action : action::accept);
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
i.forEachRemaining(action);
}
}
/**
* Wraps a standard list iterator into a type-specific list iterator.
*
*
* This method wraps a standard list iterator into a type-specific one which will handle the type
* conversions for you. Of course, any attempt to wrap an iterator returning the instances of the
* wrong class will generate a {@link ClassCastException}. The returned iterator is backed by
* {@code i}: changes to one of the iterators will affect the other, too.
*
*
* If {@code i} is already type-specific, it will returned and no new object will be generated.
*
* @param i a list iterator.
* @return a type-specific list iterator backed by {@code i}.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public static IntListIterator asIntIterator(final ListIterator i) {
if (i instanceof IntListIterator) return (IntListIterator)i;
return new ListIteratorWrapper(i);
}
/**
* Returns whether an element returned by the given iterator satisfies the given predicate.
*
* Short circuit evaluation is performed; the first {@code true} from the predicate terminates the
* loop.
*
* @return true if an element returned by {@code iterator} satisfies {@code predicate}.
*/
public static boolean any(final IntIterator iterator, final java.util.function.IntPredicate predicate) {
return indexOf(iterator, predicate) != -1;
}
/**
* Returns whether all elements returned by the given iterator satisfy the given predicate.
*
* Short circuit evaluation is performed; the first {@code false} from the predicate terminates the
* loop.
*
* @return true if all elements returned by {@code iterator} satisfy {@code predicate}.
*/
public static boolean all(final IntIterator iterator, final java.util.function.IntPredicate predicate) {
Objects.requireNonNull(predicate);
do {
if (!iterator.hasNext()) return true;
} while (predicate.test(iterator.nextInt()));
return false;
}
/**
* Returns the index of the first element returned by the given iterator that satisfies the given
* predicate, or −1 if no such element was found.
*
* The next element returned by the iterator always considered element 0, even for
* {@link java.util.ListIterator ListIterators}. In other words
* {@link java.util.ListIterator#nextIndex ListIterator.nextIndex} is ignored.
*
* @return the index of the first element returned by {@code iterator} that satisfies
* {@code predicate}, or −1 if no such element was found.
*/
public static int indexOf(final IntIterator iterator, final java.util.function.IntPredicate predicate) {
Objects.requireNonNull(predicate);
for (int i = 0; iterator.hasNext(); ++i) {
if (predicate.test(iterator.nextInt())) return i;
}
return -1;
}
/**
* A skeletal implementation for an iterator backed by an index-based data store. High performance
* concrete implementations (like the main Iterator of ArrayList) generally should avoid using this
* and just implement the interface directly, but should be decent for less performance critical
* implementations.
*
*
* This class is only appropriate for sequences that are at most {@link Integer#MAX_VALUE} long. If
* your backing data store can be bigger then this, consider the equivalently named class in the
* type specific {@code BigListIterators} class.
*
*
* As the abstract methods in this class are used in inner loops, it is generally a good idea to
* override the class as {@code final} as to encourage the JVM to inline them (or alternatively,
* override the abstract methods as final).
*/
public static abstract class AbstractIndexBasedIterator extends AbstractIntIterator {
/**
* The minimum pos can be, and is the logical start of the "range". Usually set to the initialPos
* unless it is a ListIterator, in which case it can vary.
*
* There isn't any way for a range to shift its beginning like the end can (through
* {@link #remove}), so this is final.
*/
protected final int minPos;
/**
* The current position index, the index of the item to be returned after the next call to
* {@link #next()}.
*
*
* This value will be between {@code minPos} and {@link #getMaxPos()} (exclusive) (on a best effort,
* so concurrent structural modifications outside this iterator may cause this to be violated, but
* that usually invalidates iterators anyways). Thus {@code pos} being {@code minPos + 2} would mean
* {@link #next()} was called twice and the next call will return the third element of this
* iterator.
*/
protected int pos;
/**
* The last returned index by a call to {@link #next} or, if a list-iterator,
* {@link java.util.ListIterator#previous().
*
* It is −1 if no such call has occurred or a mutation has occurred through this iterator and
* no advancement has been done.
*/
protected int lastReturned;
protected AbstractIndexBasedIterator(int minPos, int initialPos) {
this.minPos = minPos;
this.pos = initialPos;
}
// When you implement these, you should probably declare them final to encourage the JVM to inline
// them.
/**
* Get the item corresponding to the given index location.
*
*
* Do not advance {@link #pos} in this method; the default {@code next} method takes care
* of this.
*
*
* The {@code location} given will be between {@code minPos} and {@link #getMaxPos()} (exclusive).
* Thus, a {@code location} of {@code minPos + 2} would mean {@link #next()} was called twice and
* this method should return what the next call to {@link #next()} should return.
*/
protected abstract int get(int location);
/**
* Remove the item at the given index.
*
*
* Do not modify {@link #pos} in this method; the default {@code #remove()} method takes
* care of this.
*
*
* This method should also do what is needed to track the change to the {@link #getMaxPos}. Usually
* this is accomplished by having this method call the parent {@link Collection}'s appropriate
* remove method, and having {@link #getMaxPos} track the parent {@linkplain Collection#size()
* collection's size}.
*/
protected abstract void remove(int location);
/**
* The maximum pos can be, and is the logical end (exclusive) of the "range".
*
*
* If pos is equal to the return of this method, this means the last element has been returned and
* the next call to {@link #next()} will throw.
*
*
* Usually set return the parent {@linkplain Collection#size() collection's size}, but does not have
* to be (for example, sublists and subranges).
*/
protected abstract int getMaxPos();
@Override
public boolean hasNext() {
return pos < getMaxPos();
}
@Override
public int nextInt() {
if (!hasNext()) throw new NoSuchElementException();
return get(lastReturned = pos++);
}
@Override
public void remove() {
if (lastReturned == -1) throw new IllegalStateException();
remove(lastReturned);
/* If the last operation was a next(), we are removing an element *before* us, and we must decrease pos correspondingly. */
if (lastReturned < pos) pos--;
lastReturned = -1;
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
while (pos < getMaxPos()) {
action.accept(get(lastReturned = pos++));
}
}
// TODO since this method doesn't depend on the type at all, should it be "hoisted" into a
// non type-specific superclass in it.unimi.dsi.fastutil?
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
final int max = getMaxPos();
final int remaining = max - pos;
if (n < remaining) {
pos += n;
} else {
n = remaining;
pos = max;
}
lastReturned = pos - 1;
return n;
}
}
/**
* A skeletal implementation for a list-iterator backed by an index-based data store. High
* performance concrete implementations (like the main ListIterator of ArrayList) generally should
* avoid using this and just implement the interface directly, but should be decent for less
* performance critical implementations.
*
*
* This class is only appropriate for sequences that are at most {@link Integer#MAX_VALUE} long. If
* your backing data store can be bigger then this, consider the equivalently named class in the
* type specific {@code BigListSpliterators} class.
*
*
* As the abstract methods in this class are used in inner loops, it is generally a good idea to
* override the class as {@code final} as to encourage the JVM to inline them (or alternatively,
* override the abstract methods as final).
*/
public static abstract class AbstractIndexBasedListIterator extends AbstractIndexBasedIterator implements IntListIterator {
protected AbstractIndexBasedListIterator(int minPos, int initialPos) {
super(minPos, initialPos);
}
// When you implement these, you should probably declare them final to encourage the JVM to inline
// them.
/**
* Add the given item at the given index.
*
*
* This method should also do what is needed to track the change to the {@link #getMaxPos}. Usually
* this is accomplished by having this method call the parent {@link Collection}'s appropriate add
* method, and having {@link #getMaxPos} track the parent {@linkplain Collection#size() collection's
* size}.
*
*
* Do not modify {@link #pos} in this method; the default {@code #add()} method takes care
* of this.
*
*
* See {@link #pos} and {@link #get(int)} for discussion on what the location means.
*/
protected abstract void add(int location, int k);
/**
* Sets the given item at the given index.
*
*
* See {@link #pos} and {@link #get(int)} for discussion on what the location means.
*/
protected abstract void set(int location, int k);
@Override
public boolean hasPrevious() {
return pos > minPos;
}
@Override
public int previousInt() {
if (!hasPrevious()) throw new NoSuchElementException();
return get(lastReturned = --pos);
}
@Override
public int nextIndex() {
return pos;
}
@Override
public int previousIndex() {
return pos - 1;
}
@Override
public void add(final int k) {
add(pos++, k);
lastReturned = -1;
}
@Override
public void set(final int k) {
if (lastReturned == -1) throw new IllegalStateException();
set(lastReturned, k);
}
// TODO since this method doesn't depend on the type at all, should it be "hoisted" into a
// non type-specific superclass in it.unimi.dsi.fastutil?
@Override
public int back(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
final int remaining = pos - minPos;
if (n < remaining) {
pos -= n;
} else {
n = remaining;
pos = minPos;
}
lastReturned = pos;
return n;
}
}
private static class IntervalIterator implements IntListIterator {
private final int from, to;
int curr;
public IntervalIterator(final int from, final int to) {
this.from = this.curr = from;
this.to = to;
}
@Override
public boolean hasNext() {
return curr < to;
}
@Override
public boolean hasPrevious() {
return curr > from;
}
@Override
public int nextInt() {
if (!hasNext()) throw new NoSuchElementException();
return curr++;
}
@Override
public int previousInt() {
if (!hasPrevious()) throw new NoSuchElementException();
return --curr;
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
for (; curr < to; ++curr) {
action.accept(curr);
}
}
@Override
public int nextIndex() {
return curr - from;
}
@Override
public int previousIndex() {
return curr - from - 1;
}
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
if (curr + n <= to) {
curr += n;
return n;
}
n = to - curr;
curr = to;
return n;
}
@Override
public int back(int n) {
if (curr - n >= from) {
curr -= n;
return n;
}
n = curr - from;
curr = from;
return n;
}
}
/**
* Creates a type-specific list iterator over an interval.
*
*
* The type-specific list iterator returned by this method will return the elements {@code from},
* {@code from+1},…, {@code to-1}.
*
* @param from the starting element (inclusive).
* @param to the ending element (exclusive).
* @return a type-specific list iterator enumerating the elements from {@code from} to {@code to}.
*/
public static IntListIterator fromTo(final int from, final int to) {
return new IntervalIterator(from, to);
}
private static class IteratorConcatenator implements IntIterator {
final IntIterator a[];
int offset, length, lastOffset = -1;
public IteratorConcatenator(final IntIterator a[], int offset, int length) {
this.a = a;
this.offset = offset;
this.length = length;
advance();
}
private void advance() {
while (length != 0) {
if (a[offset].hasNext()) break;
length--;
offset++;
}
return;
}
@Override
public boolean hasNext() {
return length > 0;
}
@Override
public int nextInt() {
if (!hasNext()) throw new NoSuchElementException();
int next = a[lastOffset = offset].nextInt();
advance();
return next;
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
while (length > 0) {
a[lastOffset = offset].forEachRemaining(action);
advance();
}
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
while (length > 0) {
a[lastOffset = offset].forEachRemaining(action);
advance();
}
}
@Override
public void remove() {
if (lastOffset == -1) throw new IllegalStateException();
a[lastOffset].remove();
}
@Override
public int skip(int n) {
if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n);
lastOffset = -1;
int skipped = 0;
while (skipped < n && length != 0) {
skipped += a[offset].skip(n - skipped);
if (a[offset].hasNext()) break;
length--;
offset++;
}
return skipped;
}
}
/**
* Concatenates all iterators contained in an array.
*
*
* This method returns an iterator that will enumerate in order the elements returned by all
* iterators contained in the given array.
*
* @param a an array of iterators.
* @return an iterator obtained by concatenation.
*/
public static IntIterator concat(final IntIterator... a) {
return concat(a, 0, a.length);
}
/**
* Concatenates a sequence of iterators contained in an array.
*
*
* This method returns an iterator that will enumerate in order the elements returned by
* {@code a[offset]}, then those returned by {@code a[offset + 1]}, and so on up to
* {@code a[offset + length - 1]}.
*
* @param a an array of iterators.
* @param offset the index of the first iterator to concatenate.
* @param length the number of iterators to concatenate.
* @return an iterator obtained by concatenation of {@code length} elements of {@code a} starting at
* {@code offset}.
*/
public static IntIterator concat(final IntIterator a[], final int offset, final int length) {
return new IteratorConcatenator(a, offset, length);
}
/** An unmodifiable wrapper class for iterators. */
public static class UnmodifiableIterator implements IntIterator {
protected final IntIterator i;
public UnmodifiableIterator(final IntIterator i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public int nextInt() {
return i.nextInt();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
i.forEachRemaining(action);
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
i.forEachRemaining(action);
}
}
/**
* Returns an unmodifiable iterator backed by the specified iterator.
*
* @param i the iterator to be wrapped in an unmodifiable iterator.
* @return an unmodifiable view of the specified iterator.
*/
public static IntIterator unmodifiable(final IntIterator i) {
return new UnmodifiableIterator(i);
}
/** An unmodifiable wrapper class for bidirectional iterators. */
public static class UnmodifiableBidirectionalIterator implements IntBidirectionalIterator {
protected final IntBidirectionalIterator i;
public UnmodifiableBidirectionalIterator(final IntBidirectionalIterator i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public boolean hasPrevious() {
return i.hasPrevious();
}
@Override
public int nextInt() {
return i.nextInt();
}
@Override
public int previousInt() {
return i.previousInt();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
i.forEachRemaining(action);
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
i.forEachRemaining(action);
}
}
/**
* Returns an unmodifiable bidirectional iterator backed by the specified bidirectional iterator.
*
* @param i the bidirectional iterator to be wrapped in an unmodifiable bidirectional iterator.
* @return an unmodifiable view of the specified bidirectional iterator.
*/
public static IntBidirectionalIterator unmodifiable(final IntBidirectionalIterator i) {
return new UnmodifiableBidirectionalIterator(i);
}
/** An unmodifiable wrapper class for list iterators. */
public static class UnmodifiableListIterator implements IntListIterator {
protected final IntListIterator i;
public UnmodifiableListIterator(final IntListIterator i) {
this.i = i;
}
@Override
public boolean hasNext() {
return i.hasNext();
}
@Override
public boolean hasPrevious() {
return i.hasPrevious();
}
@Override
public int nextInt() {
return i.nextInt();
}
@Override
public int previousInt() {
return i.previousInt();
}
@Override
public int nextIndex() {
return i.nextIndex();
}
@Override
public int previousIndex() {
return i.previousIndex();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
i.forEachRemaining(action);
}
@Deprecated
@Override
public void forEachRemaining(final Consumer action) {
i.forEachRemaining(action);
}
}
/**
* Returns an unmodifiable list iterator backed by the specified list iterator.
*
* @param i the list iterator to be wrapped in an unmodifiable list iterator.
* @return an unmodifiable view of the specified list iterator.
*/
public static IntListIterator unmodifiable(final IntListIterator i) {
return new UnmodifiableListIterator(i);
}
/** A wrapper promoting the results of a ByteIterator. */
private final static class ByteIteratorWrapper implements IntIterator {
final it.unimi.dsi.fastutil.bytes.ByteIterator iterator;
public ByteIteratorWrapper(final it.unimi.dsi.fastutil.bytes.ByteIterator iterator) {
this.iterator = iterator;
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Deprecated
@Override
public Integer next() {
return Integer.valueOf(iterator.nextByte());
}
@Override
public int nextInt() {
return iterator.nextByte();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
iterator.forEachRemaining(action::accept);
}
@Override
public void remove() {
iterator.remove();
}
@Override
public int skip(final int n) {
return iterator.skip(n);
}
}
/**
* Returns an iterator backed by the specified byte iterator.
*
* @param iterator a byte iterator.
* @return an iterator backed by the specified byte iterator.
*/
public static IntIterator wrap(final it.unimi.dsi.fastutil.bytes.ByteIterator iterator) {
return new ByteIteratorWrapper(iterator);
}
/** A wrapper promoting the results of a ShortIterator. */
private final static class ShortIteratorWrapper implements IntIterator {
final it.unimi.dsi.fastutil.shorts.ShortIterator iterator;
public ShortIteratorWrapper(final it.unimi.dsi.fastutil.shorts.ShortIterator iterator) {
this.iterator = iterator;
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Deprecated
@Override
public Integer next() {
return Integer.valueOf(iterator.nextShort());
}
@Override
public int nextInt() {
return iterator.nextShort();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
iterator.forEachRemaining(action::accept);
}
@Override
public void remove() {
iterator.remove();
}
@Override
public int skip(final int n) {
return iterator.skip(n);
}
}
/**
* Returns an iterator backed by the specified short iterator.
*
* @param iterator a short iterator.
* @return an iterator backed by the specified short iterator.
*/
public static IntIterator wrap(final it.unimi.dsi.fastutil.shorts.ShortIterator iterator) {
return new ShortIteratorWrapper(iterator);
}
/** A wrapper promoting the results of a CharIterator. */
private final static class CharIteratorWrapper implements IntIterator {
final it.unimi.dsi.fastutil.chars.CharIterator iterator;
public CharIteratorWrapper(final it.unimi.dsi.fastutil.chars.CharIterator iterator) {
this.iterator = iterator;
}
@Override
public boolean hasNext() {
return iterator.hasNext();
}
@Deprecated
@Override
public Integer next() {
return Integer.valueOf(iterator.nextChar());
}
@Override
public int nextInt() {
return iterator.nextChar();
}
@Override
public void forEachRemaining(final java.util.function.IntConsumer action) {
Objects.requireNonNull(action);
iterator.forEachRemaining(action::accept);
}
@Override
public void remove() {
iterator.remove();
}
@Override
public int skip(final int n) {
return iterator.skip(n);
}
}
/**
* Returns an iterator backed by the specified char iterator.
*
*
* WARNING: This is not the same as converting the source to a sequence of code
* points. This returned instance literally performs {@code (int)(charValue)} casts. Surrogate pairs
* will be left as separate elements instead of combined into a single element with the code point
* it represents. See {@link Character} for more discussion on code points, char values, and
* surrogate pairs.
*
* @param iterator a char iterator.
* @return an iterator backed by the specified char iterator.
*/
public static IntIterator wrap(final it.unimi.dsi.fastutil.chars.CharIterator iterator) {
return new CharIteratorWrapper(iterator);
}
}