http://fastutil.di.unimi.it/: fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.
  • Sebastiano Vigna 
/*
	* Copyright (C) 2002-2019 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.doubles;
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;

A class providing static methods and objects that do useful things with
type-specific iterators.

See Also:
  • Iterator
/**
 * A class providing static methods and objects that do useful things with
 * type-specific iterators.
 *
 * @see Iterator
 */
public final class DoubleIterators {
	private DoubleIterators() {
	}
	
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.

/**
	 * A class returning no elements and a type-specific iterator interface.
	 *
	 * <p>
	 * This class may be useful to implement your own in case you subclass a
	 * type-specific iterator.
	 */
	public static class EmptyIterator implements DoubleListIterator, 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 double nextDouble() {
			throw new NoSuchElementException();
		}
		@Override
		public double previousDouble() {
			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 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.

/**
	 * An empty iterator. It is serializable and cloneable.
	 *
	 * <p>
	 * 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. 
/** An iterator returning a single element. */
	private static class SingletonIterator implements DoubleListIterator {
		private final double element;
		private int curr;
		public SingletonIterator(final double element) {
			this.element = element;
		}
		@Override
		public boolean hasNext() {
			return curr == 0;
		}
		@Override
		public boolean hasPrevious() {
			return curr == 1;
		}
		@Override
		public double nextDouble() {
			if (!hasNext())
				throw new NoSuchElementException();
			curr = 1;
			return element;
		}
		@Override
		public double previousDouble() {
			if (!hasPrevious())
				throw new NoSuchElementException();
			curr = 0;
			return element;
		}
		@Override
		public int nextIndex() {
			return curr;
		}
		@Override
		public int previousIndex() {
			return curr - 1;
		}
	}
	
Returns an immutable iterator that iterates just over the given element.

Params:
  • element – 
           the only element to be returned by a type-specific list iterator.
Returns:an immutable iterator that iterates just over element.
/**
	 * 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 DoubleListIterator singleton(final double element) {
		return new SingletonIterator(element);
	}
	
A class to wrap arrays in iterators. 
/** A class to wrap arrays in iterators. */
	private static class ArrayIterator implements DoubleListIterator {
		private final double[] array;
		private final int offset, length;
		private int curr;
		public ArrayIterator(final double[] 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 double nextDouble() {
			if (!hasNext())
				throw new NoSuchElementException();
			return array[offset + curr++];
		}
		@Override
		public double previousDouble() {
			if (!hasPrevious())
				throw new NoSuchElementException();
			return array[offset + --curr];
		}
		@Override
		public int skip(int n) {
			if (n <= length - curr) {
				curr += n;
				return n;
			}
			n = length - curr;
			curr = length;
			return n;
		}
		@Override
		public int back(int 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 length times, returning consecutive elements of the given array starting from the one with index offset. 
Params:
  • array – 
           an array to wrap into a type-specific list iterator.
  • offset – 
           the first element of the array to be returned.
  • length – 
           the number of elements to return.
Returns:an iterator that will return length elements of array starting at position offset.
/**
	 * Wraps the given part of an array into a type-specific list iterator.
	 *
	 * <p>
	 * 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 DoubleListIterator wrap(final double[] array, final int offset, final int length) {
		DoubleArrays.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.

Params:
  • array – 
           an array to wrap into a type-specific list iterator.
Returns:an iterator that will the elements of array.
/**
	 * Wraps the given array into a type-specific list iterator.
	 *
	 * <p>
	 * 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 the elements of {@code array}.
	 */
	public static DoubleListIterator wrap(final double[] 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 length, in the given array starting at offset. The number of actually unwrapped elements is returned (it may be less than max if the iterator emits less than max elements). 
Params:
  • i – 
           a type-specific iterator.
  • array – 
           an array to contain the output of the iterator.
  • offset – 
           the first element of the array to be returned.
  • max – 
           the maximum number of elements to unwrap.
Returns:the number of elements unwrapped.
/**
	 * Unwraps an iterator into an array starting at a given offset for a given
	 * number of elements.
	 *
	 * <p>
	 * 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 DoubleIterator i, final double 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.nextDouble();
		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.

Params:
  • i – 
           a type-specific iterator.
  • array – 
           an array to contain the output of the iterator.
Returns:the number of elements unwrapped.
/**
	 * Unwraps an iterator into an array.
	 *
	 * <p>
	 * 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 DoubleIterator i, final double 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 max elements will be returned. 
Params:
  • i – 
           a type-specific iterator.
  • max – 
           the maximum number of elements to be unwrapped.
Returns:an array containing the elements returned by the iterator (at most max).
/**
	 * Unwraps an iterator, returning an array, with a limit on the number of
	 * elements.
	 *
	 * <p>
	 * 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 double[] unwrap(final DoubleIterator i, int max) {
		if (max < 0)
			throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
		double array[] = new double[16];
		int j = 0;
		while (max-- != 0 && i.hasNext()) {
			if (j == array.length)
				array = DoubleArrays.grow(array, j + 1);
			array[j++] = i.nextDouble();
		}
		return DoubleArrays.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.

Params:
  • i – 
           a type-specific iterator.
Returns:an array containing the elements returned by the iterator.
/**
	 * Unwraps an iterator, returning an array.
	 *
	 * <p>
	 * 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 double[] unwrap(final DoubleIterator 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 length, in the given big array starting at offset. The number of actually unwrapped elements is returned (it may be less than max if the iterator emits less than max elements). 
Params:
  • i – 
           a type-specific iterator.
  • array – 
           a big array to contain the output of the iterator.
  • offset – 
           the first element of the array to be returned.
  • max – 
           the maximum number of elements to unwrap.
Returns:the number of elements unwrapped.
/**
	 * Unwraps an iterator into a big array starting at a given offset for a given
	 * number of elements.
	 *
	 * <p>
	 * 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 DoubleIterator i, final double 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.nextDouble());
		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.

Params:
  • i – 
           a type-specific iterator.
  • array – 
           a big array to contain the output of the iterator.
Returns:the number of elements unwrapped.
/**
	 * Unwraps an iterator into a big array.
	 *
	 * <p>
	 * 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 DoubleIterator i, final double 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 max, in the given type-specific collection. The number of actually unwrapped elements is returned (it may be less than max if the iterator emits less than max elements). 
Params:
  • i – 
           a type-specific iterator.
  • c – 
           a type-specific collection array to contain the output of the
           iterator.
  • max – 
           the maximum number of elements to unwrap.
Returns: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).
/**
	 * Unwraps an iterator into a type-specific collection, with a limit on the
	 * number of elements.
	 *
	 * <p>
	 * 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 DoubleIterator i, final DoubleCollection 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.nextDouble());
		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 max elements will be returned. 
Params:
  • i – 
           a type-specific iterator.
  • max – 
           the maximum number of elements to be unwrapped.
Returns:a big array containing the elements returned by the iterator (at most max).
/**
	 * Unwraps an iterator, returning a big array, with a limit on the number of
	 * elements.
	 *
	 * <p>
	 * 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 double[][] unwrapBig(final DoubleIterator i, long max) {
		if (max < 0)
			throw new IllegalArgumentException("The maximum number of elements (" + max + ") is negative");
		double array[][] = DoubleBigArrays.newBigArray(16);
		long j = 0;
		while (max-- != 0 && i.hasNext()) {
			if (j == length(array))
				array = grow(array, j + 1);
			set(array, j++, i.nextDouble());
		}
		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.

Params:
  • i – 
           a type-specific iterator.
Returns:a big array containing the elements returned by the iterator.
/**
	 * Unwraps an iterator, returning a big array.
	 *
	 * <p>
	 * 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 double[][] unwrapBig(final DoubleIterator 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.

Params:
  • i – 
           a type-specific iterator.
  • c – 
           a type-specific collection to contain the output of the iterator.
Returns: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).
/**
	 * Unwraps an iterator into a type-specific collection.
	 *
	 * <p>
	 * 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 DoubleIterator i, final DoubleCollection c) {
		long n = 0;
		while (i.hasNext()) {
			c.add(i.nextDouble());
			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 max). 
Params:
  • i – 
           a type-specific iterator.
  • s – 
           a type-specific collection.
  • max – 
           the maximum number of elements to be poured.
Returns: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).
/**
	 * Pours an iterator into a type-specific collection, with a limit on the number
	 * of elements.
	 *
	 * <p>
	 * 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 DoubleIterator i, final DoubleCollection 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.nextDouble());
		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.

Params:
  • i – 
           a type-specific iterator.
  • s – 
           a type-specific collection.
Returns: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).
/**
	 * Pours an iterator into a type-specific collection.
	 *
	 * <p>
	 * 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 DoubleIterator i, final DoubleCollection 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 max). Iteration on the returned list is guaranteed to produce the elements in the same order in which they appeared in the iterator. 
Params:
  • i – 
           a type-specific iterator.
  • max – 
           the maximum number of elements to be poured.
Returns:a type-specific list containing the returned elements, up to max.
/**
	 * Pours an iterator, returning a type-specific list, with a limit on the number
	 * of elements.
	 *
	 * <p>
	 * 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 DoubleList pour(final DoubleIterator i, int max) {
		final DoubleArrayList l = new DoubleArrayList();
		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.

Params:
  • i – 
           a type-specific iterator.
Returns:a type-specific list containing the returned elements.
/**
	 * Pours an iterator, returning a type-specific list.
	 *
	 * <p>
	 * 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 DoubleList pour(final DoubleIterator i) {
		return pour(i, Integer.MAX_VALUE);
	}
	private static class IteratorWrapper implements DoubleIterator {
		final Iterator<Double> i;
		public IteratorWrapper(final Iterator<Double> i) {
			this.i = i;
		}
		@Override
		public boolean hasNext() {
			return i.hasNext();
		}
		@Override
		public void remove() {
			i.remove();
		}
		@Override
		public double nextDouble() {
			return (i.next()).doubleValue();
		}
	}
	
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 ClassCastException. The returned iterator is backed by i: changes to one of the iterators will affect the other, too. 
 If i is already type-specific, it will returned and no new object will be generated. 
Params:
  • i – 
           an iterator.
Returns:a type-specific iterator backed by i.
/**
	 * Wraps a standard iterator into a type-specific iterator.
	 *
	 * <p>
	 * 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.
	 *
	 * <p>
	 * 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 DoubleIterator asDoubleIterator(final Iterator i) {
		if (i instanceof DoubleIterator)
			return (DoubleIterator) i;
		return new IteratorWrapper(i);
	}
	private static class ListIteratorWrapper implements DoubleListIterator {
		final ListIterator<Double> i;
		public ListIteratorWrapper(final ListIterator<Double> 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(double k) {
			i.set(Double.valueOf(k));
		}
		@Override
		public void add(double k) {
			i.add(Double.valueOf(k));
		}
		@Override
		public void remove() {
			i.remove();
		}
		@Override
		public double nextDouble() {
			return (i.next()).doubleValue();
		}
		@Override
		public double previousDouble() {
			return (i.previous()).doubleValue();
		}
	}
	
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 ClassCastException. The returned iterator is backed by i: changes to one of the iterators will affect the other, too. 
 If i is already type-specific, it will returned and no new object will be generated. 
Params:
  • i – 
           a list iterator.
Returns:a type-specific list iterator backed by i.
/**
	 * Wraps a standard list iterator into a type-specific list iterator.
	 *
	 * <p>
	 * 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.
	 *
	 * <p>
	 * 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 DoubleListIterator asDoubleIterator(final ListIterator i) {
		if (i instanceof DoubleListIterator)
			return (DoubleListIterator) i;
		return new ListIteratorWrapper(i);
	}
	public static boolean any(final DoubleIterator iterator, final java.util.function.DoublePredicate predicate) {
		return indexOf(iterator, predicate) != -1;
	}
	public static boolean all(final DoubleIterator iterator, final java.util.function.DoublePredicate predicate) {
		Objects.requireNonNull(predicate);
		do {
			if (!iterator.hasNext())
				return true;
		} while (predicate.test(iterator.nextDouble()));
		return false;
	}
	public static int indexOf(final DoubleIterator iterator, final java.util.function.DoublePredicate predicate) {
		Objects.requireNonNull(predicate);
		for (int i = 0; iterator.hasNext(); ++i) {
			if (predicate.test(iterator.nextDouble()))
				return i;
		}
		return -1;
	}
	private static class IteratorConcatenator implements DoubleIterator {
		final DoubleIterator a[];
		int offset, length, lastOffset = -1;
		public IteratorConcatenator(final DoubleIterator 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 double nextDouble() {
			if (!hasNext())
				throw new NoSuchElementException();
			double next = a[lastOffset = offset].nextDouble();
			advance();
			return next;
		}
		@Override
		public void remove() {
			if (lastOffset == -1)
				throw new IllegalStateException();
			a[lastOffset].remove();
		}
		@Override
		public int skip(int 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.

Params:
  • a – 
           an array of iterators.
Returns:an iterator obtained by concatenation.
/**
	 * Concatenates all iterators contained in an array.
	 *
	 * <p>
	 * 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 DoubleIterator concat(final DoubleIterator 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 a[offset], then those returned by a[offset + 1], and so on up to a[offset + length - 1]. 
Params:
  • a – 
           an array of iterators.
  • offset – 
           the index of the first iterator to concatenate.
  • length – 
           the number of iterators to concatenate.
Returns:an iterator obtained by concatenation of length elements of a starting at offset.
/**
	 * Concatenates a sequence of iterators contained in an array.
	 *
	 * <p>
	 * 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 DoubleIterator concat(final DoubleIterator a[], final int offset, final int length) {
		return new IteratorConcatenator(a, offset, length);
	}
	
An unmodifiable wrapper class for iterators. 
/** An unmodifiable wrapper class for iterators. */
	public static class UnmodifiableIterator implements DoubleIterator {
		protected final DoubleIterator i;
		public UnmodifiableIterator(final DoubleIterator i) {
			this.i = i;
		}
		@Override
		public boolean hasNext() {
			return i.hasNext();
		}
		@Override
		public double nextDouble() {
			return i.nextDouble();
		}
	}
	
Returns an unmodifiable iterator backed by the specified iterator.

Params:
  • i – 
           the iterator to be wrapped in an unmodifiable iterator.
Returns:an unmodifiable view of the specified iterator.
/**
	 * 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 DoubleIterator unmodifiable(final DoubleIterator i) {
		return new UnmodifiableIterator(i);
	}
	
An unmodifiable wrapper class for bidirectional iterators. 
/** An unmodifiable wrapper class for bidirectional iterators. */
	public static class UnmodifiableBidirectionalIterator implements DoubleBidirectionalIterator {
		protected final DoubleBidirectionalIterator i;
		public UnmodifiableBidirectionalIterator(final DoubleBidirectionalIterator i) {
			this.i = i;
		}
		@Override
		public boolean hasNext() {
			return i.hasNext();
		}
		@Override
		public boolean hasPrevious() {
			return i.hasPrevious();
		}
		@Override
		public double nextDouble() {
			return i.nextDouble();
		}
		@Override
		public double previousDouble() {
			return i.previousDouble();
		}
	}
	
Returns an unmodifiable bidirectional iterator backed by the specified
bidirectional iterator.

Params:
  • i – 
           the bidirectional iterator to be wrapped in an unmodifiable
           bidirectional iterator.
Returns:an unmodifiable view of the specified bidirectional iterator.
/**
	 * 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 DoubleBidirectionalIterator unmodifiable(final DoubleBidirectionalIterator i) {
		return new UnmodifiableBidirectionalIterator(i);
	}
	
An unmodifiable wrapper class for list iterators. 
/** An unmodifiable wrapper class for list iterators. */
	public static class UnmodifiableListIterator implements DoubleListIterator {
		protected final DoubleListIterator i;
		public UnmodifiableListIterator(final DoubleListIterator i) {
			this.i = i;
		}
		@Override
		public boolean hasNext() {
			return i.hasNext();
		}
		@Override
		public boolean hasPrevious() {
			return i.hasPrevious();
		}
		@Override
		public double nextDouble() {
			return i.nextDouble();
		}
		@Override
		public double previousDouble() {
			return i.previousDouble();
		}
		@Override
		public int nextIndex() {
			return i.nextIndex();
		}
		@Override
		public int previousIndex() {
			return i.previousIndex();
		}
	}
	
Returns an unmodifiable list iterator backed by the specified list iterator.

Params:
  • i – 
           the list iterator to be wrapped in an unmodifiable list iterator.
Returns:an unmodifiable view of the specified list iterator.
/**
	 * 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 DoubleListIterator unmodifiable(final DoubleListIterator i) {
		return new UnmodifiableListIterator(i);
	}
	
A wrapper promoting the results of a ByteIterator. 
/** A wrapper promoting the results of a ByteIterator. */
	protected static class ByteIteratorWrapper implements DoubleIterator {
		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 Double next() {
			return Double.valueOf(iterator.nextByte());
		}
		@Override
		public double nextDouble() {
			return iterator.nextByte();
		}
		@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.

Params:
  • iterator – 
           a byte iterator.
Returns:an iterator backed by the specified byte iterator.
/**
	 * 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 DoubleIterator wrap(final it.unimi.dsi.fastutil.bytes.ByteIterator iterator) {
		return new ByteIteratorWrapper(iterator);
	}
	
A wrapper promoting the results of a ShortIterator. 
/** A wrapper promoting the results of a ShortIterator. */
	protected static class ShortIteratorWrapper implements DoubleIterator {
		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 Double next() {
			return Double.valueOf(iterator.nextShort());
		}
		@Override
		public double nextDouble() {
			return iterator.nextShort();
		}
		@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.

Params:
  • iterator – 
           a short iterator.
Returns:an iterator backed by the specified short iterator.
/**
	 * 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 DoubleIterator wrap(final it.unimi.dsi.fastutil.shorts.ShortIterator iterator) {
		return new ShortIteratorWrapper(iterator);
	}
	
A wrapper promoting the results of an IntIterator. 
/** A wrapper promoting the results of an IntIterator. */
	protected static class IntIteratorWrapper implements DoubleIterator {
		final it.unimi.dsi.fastutil.ints.IntIterator iterator;
		public IntIteratorWrapper(final it.unimi.dsi.fastutil.ints.IntIterator iterator) {
			this.iterator = iterator;
		}
		@Override
		public boolean hasNext() {
			return iterator.hasNext();
		}
		@Deprecated
		@Override
		public Double next() {
			return Double.valueOf(iterator.nextInt());
		}
		@Override
		public double nextDouble() {
			return iterator.nextInt();
		}
		@Override
		public void remove() {
			iterator.remove();
		}
		@Override
		public int skip(final int n) {
			return iterator.skip(n);
		}
	}
	
Returns an iterator backed by the specified integer iterator.

Params:
  • iterator – 
           an integer iterator.
Returns:an iterator backed by the specified integer iterator.
/**
	 * Returns an iterator backed by the specified integer iterator.
	 * 
	 * @param iterator
	 *            an integer iterator.
	 * @return an iterator backed by the specified integer iterator.
	 */
	public static DoubleIterator wrap(final it.unimi.dsi.fastutil.ints.IntIterator iterator) {
		return new IntIteratorWrapper(iterator);
	}
	
A wrapper promoting the results of a FloatIterator. 
/** A wrapper promoting the results of a FloatIterator. */
	protected static class FloatIteratorWrapper implements DoubleIterator {
		final it.unimi.dsi.fastutil.floats.FloatIterator iterator;
		public FloatIteratorWrapper(final it.unimi.dsi.fastutil.floats.FloatIterator iterator) {
			this.iterator = iterator;
		}
		@Override
		public boolean hasNext() {
			return iterator.hasNext();
		}
		@Deprecated
		@Override
		public Double next() {
			return Double.valueOf(iterator.nextFloat());
		}
		@Override
		public double nextDouble() {
			return iterator.nextFloat();
		}
		@Override
		public void remove() {
			iterator.remove();
		}
		@Override
		public int skip(final int n) {
			return iterator.skip(n);
		}
	}
	
Returns an iterator backed by the specified float iterator.

Params:
  • iterator – 
           a float iterator.
Returns:an iterator backed by the specified float iterator.
/**
	 * Returns an iterator backed by the specified float iterator.
	 * 
	 * @param iterator
	 *            a float iterator.
	 * @return an iterator backed by the specified float iterator.
	 */
	public static DoubleIterator wrap(final it.unimi.dsi.fastutil.floats.FloatIterator iterator) {
		return new FloatIteratorWrapper(iterator);
	}
}