/*
	* 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.bytes;
import it.unimi.dsi.fastutil.Hash;
import it.unimi.dsi.fastutil.HashCommon;
import static it.unimi.dsi.fastutil.HashCommon.arraySize;
import static it.unimi.dsi.fastutil.HashCommon.maxFill;
import java.util.Map;
import java.util.Arrays;
import java.util.NoSuchElementException;
import java.util.function.Consumer;
import it.unimi.dsi.fastutil.bytes.ByteCollection;
import it.unimi.dsi.fastutil.bytes.AbstractByteCollection;
import it.unimi.dsi.fastutil.bytes.ByteIterator;
import java.util.Comparator;
import it.unimi.dsi.fastutil.bytes.ByteListIterator;
import it.unimi.dsi.fastutil.objects.AbstractObjectSortedSet;
import it.unimi.dsi.fastutil.objects.ObjectListIterator;
import it.unimi.dsi.fastutil.objects.ObjectBidirectionalIterator;
import it.unimi.dsi.fastutil.objects.ObjectSortedSet;
A type-specific linked hash map with with a fast, small-footprint
implementation.

Instances of this class use a hash table to represent a map. The table is
filled up to a specified load factor, and then doubled in size to
accommodate new entries. If the table is emptied below one fourth of
the load factor, it is halved in size; however, the table is never reduced to
a size smaller than that at creation time: this approach makes it possible to
create maps with a large capacity in which insertions and deletions do not
cause immediately rehashing. Moreover, halving is not performed when deleting
entries from an iterator, as it would interfere with the iteration process.
 Note that clear() does not modify the hash table size. Rather, a family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class. 

Iterators generated by this map will enumerate pairs in the same order in
which they have been added to the map (addition of pairs whose key is already
present in the map does not change the iteration order). Note that this order
has nothing in common with the natural order of the keys. The order is kept
by means of a doubly linked list, represented via an array of longs
parallel to the table.
 This class implements the interface of a sorted map, so to allow easy access of the iteration order: for instance, you can get the first key in iteration order with firstKey() without having to create an iterator; however, this class partially violates the SortedMap contract because all submap methods throw an exception and comparator() returns always null. 
 Additional methods, such as getAndMoveToFirst(), make it easy to use instances of this class as a cache (e.g., with LRU policy). 
 The iterators provided by the views of this class using are type-specific list iterators, and can be started at any element which is a key of the map, or a NoSuchElementException exception will be thrown. If, however, the provided element is not the first or last key in the map, the first access to the list index will require linear time, as in the worst case the entire key set must be scanned in iteration order to retrieve the positional index of the starting key. If you use just the methods of a type-specific BidirectionalIterator, however, all operations will be performed in constant time. 
See Also:
Hash
HashCommon/**
 * A type-specific linked hash map with with a fast, small-footprint
 * implementation.
 *
 * <p>
 * Instances of this class use a hash table to represent a map. The table is
 * filled up to a specified <em>load factor</em>, and then doubled in size to
 * accommodate new entries. If the table is emptied below <em>one fourth</em> of
 * the load factor, it is halved in size; however, the table is never reduced to
 * a size smaller than that at creation time: this approach makes it possible to
 * create maps with a large capacity in which insertions and deletions do not
 * cause immediately rehashing. Moreover, halving is not performed when deleting
 * entries from an iterator, as it would interfere with the iteration process.
 *
 * <p>
 * Note that {@link #clear()} does not modify the hash table size. Rather, a
 * family of {@linkplain #trim() trimming methods} lets you control the size of
 * the table; this is particularly useful if you reuse instances of this class.
 *
 * <p>
 * Iterators generated by this map will enumerate pairs in the same order in
 * which they have been added to the map (addition of pairs whose key is already
 * present in the map does not change the iteration order). Note that this order
 * has nothing in common with the natural order of the keys. The order is kept
 * by means of a doubly linked list, represented <i>via</i> an array of longs
 * parallel to the table.
 *
 * <p>
 * This class implements the interface of a sorted map, so to allow easy access
 * of the iteration order: for instance, you can get the first key in iteration
 * order with {@code firstKey()} without having to create an iterator; however,
 * this class partially violates the {@link java.util.SortedMap} contract
 * because all submap methods throw an exception and {@link #comparator()}
 * returns always {@code null}.
 *
 * <p>
 * Additional methods, such as {@code getAndMoveToFirst()}, make it easy to use
 * instances of this class as a cache (e.g., with LRU policy).
 *
 * <p>
 * The iterators provided by the views of this class using are type-specific
 * {@linkplain java.util.ListIterator list iterators}, and can be started at any
 * element <em>which is a key of the map</em>, or a
 * {@link NoSuchElementException} exception will be thrown. If, however, the
 * provided element is not the first or last key in the map, the first access to
 * the list index will require linear time, as in the worst case the entire key
 * set must be scanned in iteration order to retrieve the positional index of
 * the starting key. If you use just the methods of a type-specific
 * {@link it.unimi.dsi.fastutil.BidirectionalIterator}, however, all operations
 * will be performed in constant time.
 *
 * @see Hash
 * @see HashCommon
 */
public class Byte2ByteLinkedOpenHashMap extends AbstractByte2ByteSortedMap
		implements
			java.io.Serializable,
			Cloneable,
			Hash {
	private static final long serialVersionUID = 0L;
	private static final boolean ASSERTS = false;
	
The array of keys. /** The array of keys. */
	protected transient byte[] key;
	
The array of values. /** The array of values. */
	protected transient byte[] value;
	
The mask for wrapping a position counter. /** The mask for wrapping a position counter. */
	protected transient int mask;
	
Whether this map contains the key zero. /** Whether this map contains the key zero. */
	protected transient boolean containsNullKey;
	
The index of the first entry in iteration order. It is valid iff size is nonzero; otherwise, it contains -1. /**
	 * The index of the first entry in iteration order. It is valid iff
	 * {@link #size} is nonzero; otherwise, it contains -1.
	 */
	protected transient int first = -1;
	
The index of the last entry in iteration order. It is valid iff size is nonzero; otherwise, it contains -1. /**
	 * The index of the last entry in iteration order. It is valid iff {@link #size}
	 * is nonzero; otherwise, it contains -1.
	 */
	protected transient int last = -1;
	
For each entry, the next and the previous entry in iteration order, stored as ((prev & 0xFFFFFFFFL) << 32) | (next & 0xFFFFFFFFL). The first entry contains predecessor -1, and the last entry contains successor -1. /**
	 * For each entry, the next and the previous entry in iteration order, stored as
	 * {@code ((prev & 0xFFFFFFFFL) << 32) | (next & 0xFFFFFFFFL)}. The first entry
	 * contains predecessor -1, and the last entry contains successor -1.
	 */
	protected transient long[] link;
	
The current table size. /** The current table size. */
	protected transient int n;
	
Threshold after which we rehash. It must be the table size times f. /**
	 * Threshold after which we rehash. It must be the table size times {@link #f}.
	 */
	protected transient int maxFill;
	
We never resize below this threshold, which is the construction-time {#n}.
/**
	 * We never resize below this threshold, which is the construction-time {#n}.
	 */
	protected final transient int minN;
	
Number of entries in the set (including the key zero, if present). /** Number of entries in the set (including the key zero, if present). */
	protected int size;
	
The acceptable load factor. /** The acceptable load factor. */
	protected final float f;
	
Cached set of entries. /** Cached set of entries. */
	protected transient FastSortedEntrySet entries;
	
Cached set of keys. /** Cached set of keys. */
	protected transient ByteSortedSet keys;
	
Cached collection of values. /** Cached collection of values. */
	protected transient ByteCollection values;
	
Creates a new hash map.
 The actual table size will be the least power of two greater than expected/f. 
Params:
expected – 
           the expected number of elements in the hash map.
f – 
           the load factor./**
	 * Creates a new hash map.
	 *
	 * <p>
	 * The actual table size will be the least power of two greater than
	 * {@code expected}/{@code f}.
	 *
	 * @param expected
	 *            the expected number of elements in the hash map.
	 * @param f
	 *            the load factor.
	 */

	public Byte2ByteLinkedOpenHashMap(final int expected, final float f) {
		if (f <= 0 || f > 1)
			throw new IllegalArgumentException("Load factor must be greater than 0 and smaller than or equal to 1");
		if (expected < 0)
			throw new IllegalArgumentException("The expected number of elements must be nonnegative");
		this.f = f;
		minN = n = arraySize(expected, f);
		mask = n - 1;
		maxFill = maxFill(n, f);
		key = new byte[n + 1];
		value = new byte[n + 1];
		link = new long[n + 1];
	}
	
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor. 
Params:
expected – 
           the expected number of elements in the hash map./**
	 * Creates a new hash map with {@link Hash#DEFAULT_LOAD_FACTOR} as load factor.
	 *
	 * @param expected
	 *            the expected number of elements in the hash map.
	 */
	public Byte2ByteLinkedOpenHashMap(final int expected) {
		this(expected, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash map with initial expected Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor. /**
	 * Creates a new hash map with initial expected
	 * {@link Hash#DEFAULT_INITIAL_SIZE} entries and
	 * {@link Hash#DEFAULT_LOAD_FACTOR} as load factor.
	 */
	public Byte2ByteLinkedOpenHashMap() {
		this(DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash map copying a given one.
Params:
m –  a Map to be copied into the new hash map.
f – 
           the load factor./**
	 * Creates a new hash map copying a given one.
	 *
	 * @param m
	 *            a {@link Map} to be copied into the new hash map.
	 * @param f
	 *            the load factor.
	 */
	public Byte2ByteLinkedOpenHashMap(final Map<? extends Byte, ? extends Byte> m, final float f) {
		this(m.size(), f);
		putAll(m);
	}
	
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one. 
Params:
m –  a Map to be copied into the new hash map./**
	 * Creates a new hash map with {@link Hash#DEFAULT_LOAD_FACTOR} as load factor
	 * copying a given one.
	 *
	 * @param m
	 *            a {@link Map} to be copied into the new hash map.
	 */
	public Byte2ByteLinkedOpenHashMap(final Map<? extends Byte, ? extends Byte> m) {
		this(m, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash map copying a given type-specific one.
Params:
m – 
           a type-specific map to be copied into the new hash map.
f – 
           the load factor./**
	 * Creates a new hash map copying a given type-specific one.
	 *
	 * @param m
	 *            a type-specific map to be copied into the new hash map.
	 * @param f
	 *            the load factor.
	 */
	public Byte2ByteLinkedOpenHashMap(final Byte2ByteMap m, final float f) {
		this(m.size(), f);
		putAll(m);
	}
	
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one. 
Params:
m – 
           a type-specific map to be copied into the new hash map./**
	 * Creates a new hash map with {@link Hash#DEFAULT_LOAD_FACTOR} as load factor
	 * copying a given type-specific one.
	 *
	 * @param m
	 *            a type-specific map to be copied into the new hash map.
	 */
	public Byte2ByteLinkedOpenHashMap(final Byte2ByteMap m) {
		this(m, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash map using the elements of two parallel arrays.
Params:
k – 
           the array of keys of the new hash map.
v – 
           the array of corresponding values in the new hash map.
f – 
           the load factor.
Throws:
IllegalArgumentException –  if k and v have different lengths./**
	 * Creates a new hash map using the elements of two parallel arrays.
	 *
	 * @param k
	 *            the array of keys of the new hash map.
	 * @param v
	 *            the array of corresponding values in the new hash map.
	 * @param f
	 *            the load factor.
	 * @throws IllegalArgumentException
	 *             if {@code k} and {@code v} have different lengths.
	 */
	public Byte2ByteLinkedOpenHashMap(final byte[] k, final byte[] v, final float f) {
		this(k.length, f);
		if (k.length != v.length)
			throw new IllegalArgumentException(
					"The key array and the value array have different lengths (" + k.length + " and " + v.length + ")");
		for (int i = 0; i < k.length; i++)
			this.put(k[i], v[i]);
	}
	
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor using the elements of two parallel arrays. 
Params:
k – 
           the array of keys of the new hash map.
v – 
           the array of corresponding values in the new hash map.
Throws:
IllegalArgumentException –  if k and v have different lengths./**
	 * Creates a new hash map with {@link Hash#DEFAULT_LOAD_FACTOR} as load factor
	 * using the elements of two parallel arrays.
	 *
	 * @param k
	 *            the array of keys of the new hash map.
	 * @param v
	 *            the array of corresponding values in the new hash map.
	 * @throws IllegalArgumentException
	 *             if {@code k} and {@code v} have different lengths.
	 */
	public Byte2ByteLinkedOpenHashMap(final byte[] k, final byte[] v) {
		this(k, v, DEFAULT_LOAD_FACTOR);
	}
	private int realSize() {
		return containsNullKey ? size - 1 : size;
	}
	private void ensureCapacity(final int capacity) {
		final int needed = arraySize(capacity, f);
		if (needed > n)
			rehash(needed);
	}
	private void tryCapacity(final long capacity) {
		final int needed = (int) Math.min(1 << 30,
				Math.max(2, HashCommon.nextPowerOfTwo((long) Math.ceil(capacity / f))));
		if (needed > n)
			rehash(needed);
	}
	private byte removeEntry(final int pos) {
		final byte oldValue = value[pos];
		size--;
		fixPointers(pos);
		shiftKeys(pos);
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return oldValue;
	}
	private byte removeNullEntry() {
		containsNullKey = false;
		final byte oldValue = value[n];
		size--;
		fixPointers(n);
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return oldValue;
	}
	@Override
	public void putAll(Map<? extends Byte, ? extends Byte> m) {
		if (f <= .5)
			ensureCapacity(m.size()); // The resulting map will be sized for m.size() elements
		else
			tryCapacity(size() + m.size()); // The resulting map will be tentatively sized for size() + m.size()
											// elements
		super.putAll(m);
	}

	private int find(final byte k) {
		if (((k) == ((byte) 0)))
			return containsNullKey ? n : -(n + 1);
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return -(pos + 1);
		if (((k) == (curr)))
			return pos;
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return -(pos + 1);
			if (((k) == (curr)))
				return pos;
		}
	}
	private void insert(final int pos, final byte k, final byte v) {
		if (pos == n)
			containsNullKey = true;
		key[pos] = k;
		value[pos] = v;
		if (size == 0) {
			first = last = pos;
			// Special case of SET_UPPER_LOWER(link[pos], -1, -1);
			link[pos] = -1L;
		} else {
			link[last] ^= ((link[last] ^ (pos & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[pos] = ((last & 0xFFFFFFFFL) << 32) | (-1 & 0xFFFFFFFFL);
			last = pos;
		}
		if (size++ >= maxFill)
			rehash(arraySize(size + 1, f));
		if (ASSERTS)
			checkTable();
	}
	@Override
	public byte put(final byte k, final byte v) {
		final int pos = find(k);
		if (pos < 0) {
			insert(-pos - 1, k, v);
			return defRetValue;
		}
		final byte oldValue = value[pos];
		value[pos] = v;
		return oldValue;
	}
	private byte addToValue(final int pos, final byte incr) {
		final byte oldValue = value[pos];
		value[pos] = (byte) (oldValue + incr);
		return oldValue;
	}
	
Adds an increment to value currently associated with a key.
 Note that this method respects the default
return value semantics: when called with a key that does not currently appears in the map, the key will be associated with the default return value plus the given increment. 
Params:
k – 
           the key.
incr – 
           the increment.
Returns:
the old value, or the default
        return value if no value was present for the given key./**
	 * Adds an increment to value currently associated with a key.
	 *
	 * <p>
	 * Note that this method respects the {@linkplain #defaultReturnValue() default
	 * return value} semantics: when called with a key that does not currently
	 * appears in the map, the key will be associated with the default return value
	 * plus the given increment.
	 *
	 * @param k
	 *            the key.
	 * @param incr
	 *            the increment.
	 * @return the old value, or the {@linkplain #defaultReturnValue() default
	 *         return value} if no value was present for the given key.
	 */
	public byte addTo(final byte k, final byte incr) {
		int pos;
		if (((k) == ((byte) 0))) {
			if (containsNullKey)
				return addToValue(n, incr);
			pos = n;
			containsNullKey = true;
		} else {
			byte curr;
			final byte[] key = this.key;
			// The starting point.
			if (!((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0))) {
				if (((curr) == (k)))
					return addToValue(pos, incr);
				while (!((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
					if (((curr) == (k)))
						return addToValue(pos, incr);
			}
		}
		key[pos] = k;
		value[pos] = (byte) (defRetValue + incr);
		if (size == 0) {
			first = last = pos;
			// Special case of SET_UPPER_LOWER(link[pos], -1, -1);
			link[pos] = -1L;
		} else {
			link[last] ^= ((link[last] ^ (pos & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[pos] = ((last & 0xFFFFFFFFL) << 32) | (-1 & 0xFFFFFFFFL);
			last = pos;
		}
		if (size++ >= maxFill)
			rehash(arraySize(size + 1, f));
		if (ASSERTS)
			checkTable();
		return defRetValue;
	}
	
Shifts left entries with the specified hash code, starting at the specified
position, and empties the resulting free entry.
Params:
pos – 
           a starting position./**
	 * Shifts left entries with the specified hash code, starting at the specified
	 * position, and empties the resulting free entry.
	 *
	 * @param pos
	 *            a starting position.
	 */
	protected final void shiftKeys(int pos) {
		// Shift entries with the same hash.
		int last, slot;
		byte curr;
		final byte[] key = this.key;
		for (;;) {
			pos = ((last = pos) + 1) & mask;
			for (;;) {
				if (((curr = key[pos]) == ((byte) 0))) {
					key[last] = ((byte) 0);
					return;
				}
				slot = (it.unimi.dsi.fastutil.HashCommon.mix((curr))) & mask;
				if (last <= pos ? last >= slot || slot > pos : last >= slot && slot > pos)
					break;
				pos = (pos + 1) & mask;
			}
			key[last] = curr;
			value[last] = value[pos];
			fixPointers(pos, last);
		}
	}
	@Override

	public byte remove(final byte k) {
		if (((k) == ((byte) 0))) {
			if (containsNullKey)
				return removeNullEntry();
			return defRetValue;
		}
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return defRetValue;
		if (((k) == (curr)))
			return removeEntry(pos);
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return defRetValue;
			if (((k) == (curr)))
				return removeEntry(pos);
		}
	}
	private byte setValue(final int pos, final byte v) {
		final byte oldValue = value[pos];
		value[pos] = v;
		return oldValue;
	}
	
Removes the mapping associated with the first key in iteration order.
Throws:
NoSuchElementException – 
            is this map is empty.
Returns:
the value previously associated with the first key in iteration
        order./**
	 * Removes the mapping associated with the first key in iteration order.
	 * 
	 * @return the value previously associated with the first key in iteration
	 *         order.
	 * @throws NoSuchElementException
	 *             is this map is empty.
	 */
	public byte removeFirstByte() {
		if (size == 0)
			throw new NoSuchElementException();
		final int pos = first;
		// Abbreviated version of fixPointers(pos)
		first = (int) link[pos];
		if (0 <= first) {
			// Special case of SET_PREV(link[first], -1)
			link[first] |= (-1 & 0xFFFFFFFFL) << 32;
		}
		size--;
		final byte v = value[pos];
		if (pos == n) {
			containsNullKey = false;
		} else
			shiftKeys(pos);
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return v;
	}
	
Removes the mapping associated with the last key in iteration order.
Throws:
NoSuchElementException – 
            is this map is empty.
Returns:
the value previously associated with the last key in iteration order./**
	 * Removes the mapping associated with the last key in iteration order.
	 * 
	 * @return the value previously associated with the last key in iteration order.
	 * @throws NoSuchElementException
	 *             is this map is empty.
	 */
	public byte removeLastByte() {
		if (size == 0)
			throw new NoSuchElementException();
		final int pos = last;
		// Abbreviated version of fixPointers(pos)
		last = (int) (link[pos] >>> 32);
		if (0 <= last) {
			// Special case of SET_NEXT(link[last], -1)
			link[last] |= -1 & 0xFFFFFFFFL;
		}
		size--;
		final byte v = value[pos];
		if (pos == n) {
			containsNullKey = false;
		} else
			shiftKeys(pos);
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return v;
	}
	private void moveIndexToFirst(final int i) {
		if (size == 1 || first == i)
			return;
		if (last == i) {
			last = (int) (link[i] >>> 32);
			// Special case of SET_NEXT(link[last], -1);
			link[last] |= -1 & 0xFFFFFFFFL;
		} else {
			final long linki = link[i];
			final int prev = (int) (linki >>> 32);
			final int next = (int) linki;
			link[prev] ^= ((link[prev] ^ (linki & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[next] ^= ((link[next] ^ (linki & 0xFFFFFFFF00000000L)) & 0xFFFFFFFF00000000L);
		}
		link[first] ^= ((link[first] ^ ((i & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
		link[i] = ((-1 & 0xFFFFFFFFL) << 32) | (first & 0xFFFFFFFFL);
		first = i;
	}
	private void moveIndexToLast(final int i) {
		if (size == 1 || last == i)
			return;
		if (first == i) {
			first = (int) link[i];
			// Special case of SET_PREV(link[first], -1);
			link[first] |= (-1 & 0xFFFFFFFFL) << 32;
		} else {
			final long linki = link[i];
			final int prev = (int) (linki >>> 32);
			final int next = (int) linki;
			link[prev] ^= ((link[prev] ^ (linki & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[next] ^= ((link[next] ^ (linki & 0xFFFFFFFF00000000L)) & 0xFFFFFFFF00000000L);
		}
		link[last] ^= ((link[last] ^ (i & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
		link[i] = ((last & 0xFFFFFFFFL) << 32) | (-1 & 0xFFFFFFFFL);
		last = i;
	}
	
Returns the value to which the given key is mapped; if the key is present, it
is moved to the first position of the iteration order.
Params:
k – 
           the key.
Returns:
the corresponding value, or the 
        default return value if no value was present for the given key./**
	 * Returns the value to which the given key is mapped; if the key is present, it
	 * is moved to the first position of the iteration order.
	 *
	 * @param k
	 *            the key.
	 * @return the corresponding value, or the {@linkplain #defaultReturnValue()
	 *         default return value} if no value was present for the given key.
	 */
	public byte getAndMoveToFirst(final byte k) {
		if (((k) == ((byte) 0))) {
			if (containsNullKey) {
				moveIndexToFirst(n);
				return value[n];
			}
			return defRetValue;
		}
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return defRetValue;
		if (((k) == (curr))) {
			moveIndexToFirst(pos);
			return value[pos];
		}
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return defRetValue;
			if (((k) == (curr))) {
				moveIndexToFirst(pos);
				return value[pos];
			}
		}
	}
	
Returns the value to which the given key is mapped; if the key is present, it
is moved to the last position of the iteration order.
Params:
k – 
           the key.
Returns:
the corresponding value, or the 
        default return value if no value was present for the given key./**
	 * Returns the value to which the given key is mapped; if the key is present, it
	 * is moved to the last position of the iteration order.
	 *
	 * @param k
	 *            the key.
	 * @return the corresponding value, or the {@linkplain #defaultReturnValue()
	 *         default return value} if no value was present for the given key.
	 */
	public byte getAndMoveToLast(final byte k) {
		if (((k) == ((byte) 0))) {
			if (containsNullKey) {
				moveIndexToLast(n);
				return value[n];
			}
			return defRetValue;
		}
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return defRetValue;
		if (((k) == (curr))) {
			moveIndexToLast(pos);
			return value[pos];
		}
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return defRetValue;
			if (((k) == (curr))) {
				moveIndexToLast(pos);
				return value[pos];
			}
		}
	}
	
Adds a pair to the map; if the key is already present, it is moved to the
first position of the iteration order.
Params:
k – 
           the key.
v – 
           the value.
Returns:
the old value, or the default
        return value if no value was present for the given key./**
	 * Adds a pair to the map; if the key is already present, it is moved to the
	 * first position of the iteration order.
	 *
	 * @param k
	 *            the key.
	 * @param v
	 *            the value.
	 * @return the old value, or the {@linkplain #defaultReturnValue() default
	 *         return value} if no value was present for the given key.
	 */
	public byte putAndMoveToFirst(final byte k, final byte v) {
		int pos;
		if (((k) == ((byte) 0))) {
			if (containsNullKey) {
				moveIndexToFirst(n);
				return setValue(n, v);
			}
			containsNullKey = true;
			pos = n;
		} else {
			byte curr;
			final byte[] key = this.key;
			// The starting point.
			if (!((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0))) {
				if (((curr) == (k))) {
					moveIndexToFirst(pos);
					return setValue(pos, v);
				}
				while (!((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
					if (((curr) == (k))) {
						moveIndexToFirst(pos);
						return setValue(pos, v);
					}
			}
		}
		key[pos] = k;
		value[pos] = v;
		if (size == 0) {
			first = last = pos;
			// Special case of SET_UPPER_LOWER(link[pos], -1, -1);
			link[pos] = -1L;
		} else {
			link[first] ^= ((link[first] ^ ((pos & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
			link[pos] = ((-1 & 0xFFFFFFFFL) << 32) | (first & 0xFFFFFFFFL);
			first = pos;
		}
		if (size++ >= maxFill)
			rehash(arraySize(size, f));
		if (ASSERTS)
			checkTable();
		return defRetValue;
	}
	
Adds a pair to the map; if the key is already present, it is moved to the
last position of the iteration order.
Params:
k – 
           the key.
v – 
           the value.
Returns:
the old value, or the default
        return value if no value was present for the given key./**
	 * Adds a pair to the map; if the key is already present, it is moved to the
	 * last position of the iteration order.
	 *
	 * @param k
	 *            the key.
	 * @param v
	 *            the value.
	 * @return the old value, or the {@linkplain #defaultReturnValue() default
	 *         return value} if no value was present for the given key.
	 */
	public byte putAndMoveToLast(final byte k, final byte v) {
		int pos;
		if (((k) == ((byte) 0))) {
			if (containsNullKey) {
				moveIndexToLast(n);
				return setValue(n, v);
			}
			containsNullKey = true;
			pos = n;
		} else {
			byte curr;
			final byte[] key = this.key;
			// The starting point.
			if (!((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0))) {
				if (((curr) == (k))) {
					moveIndexToLast(pos);
					return setValue(pos, v);
				}
				while (!((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
					if (((curr) == (k))) {
						moveIndexToLast(pos);
						return setValue(pos, v);
					}
			}
		}
		key[pos] = k;
		value[pos] = v;
		if (size == 0) {
			first = last = pos;
			// Special case of SET_UPPER_LOWER(link[pos], -1, -1);
			link[pos] = -1L;
		} else {
			link[last] ^= ((link[last] ^ (pos & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[pos] = ((last & 0xFFFFFFFFL) << 32) | (-1 & 0xFFFFFFFFL);
			last = pos;
		}
		if (size++ >= maxFill)
			rehash(arraySize(size, f));
		if (ASSERTS)
			checkTable();
		return defRetValue;
	}
	@Override

	public byte get(final byte k) {
		if (((k) == ((byte) 0)))
			return containsNullKey ? value[n] : defRetValue;
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return defRetValue;
		if (((k) == (curr)))
			return value[pos];
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return defRetValue;
			if (((k) == (curr)))
				return value[pos];
		}
	}
	@Override

	public boolean containsKey(final byte k) {
		if (((k) == ((byte) 0)))
			return containsNullKey;
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return false;
		if (((k) == (curr)))
			return true;
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return false;
			if (((k) == (curr)))
				return true;
		}
	}
	@Override
	public boolean containsValue(final byte v) {
		final byte value[] = this.value;
		final byte key[] = this.key;
		if (containsNullKey && ((value[n]) == (v)))
			return true;
		for (int i = n; i-- != 0;)
			if (!((key[i]) == ((byte) 0)) && ((value[i]) == (v)))
				return true;
		return false;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override

	public byte getOrDefault(final byte k, final byte defaultValue) {
		if (((k) == ((byte) 0)))
			return containsNullKey ? value[n] : defaultValue;
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return defaultValue;
		if (((k) == (curr)))
			return value[pos];
		// There's always an unused entry.
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return defaultValue;
			if (((k) == (curr)))
				return value[pos];
		}
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte putIfAbsent(final byte k, final byte v) {
		final int pos = find(k);
		if (pos >= 0)
			return value[pos];
		insert(-pos - 1, k, v);
		return defRetValue;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override

	public boolean remove(final byte k, final byte v) {
		if (((k) == ((byte) 0))) {
			if (containsNullKey && ((v) == (value[n]))) {
				removeNullEntry();
				return true;
			}
			return false;
		}
		byte curr;
		final byte[] key = this.key;
		int pos;
		// The starting point.
		if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
			return false;
		if (((k) == (curr)) && ((v) == (value[pos]))) {
			removeEntry(pos);
			return true;
		}
		while (true) {
			if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
				return false;
			if (((k) == (curr)) && ((v) == (value[pos]))) {
				removeEntry(pos);
				return true;
			}
		}
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public boolean replace(final byte k, final byte oldValue, final byte v) {
		final int pos = find(k);
		if (pos < 0 || !((oldValue) == (value[pos])))
			return false;
		value[pos] = v;
		return true;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte replace(final byte k, final byte v) {
		final int pos = find(k);
		if (pos < 0)
			return defRetValue;
		final byte oldValue = value[pos];
		value[pos] = v;
		return oldValue;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte computeIfAbsent(final byte k, final java.util.function.IntUnaryOperator mappingFunction) {
		java.util.Objects.requireNonNull(mappingFunction);
		final int pos = find(k);
		if (pos >= 0)
			return value[pos];
		final byte newValue = it.unimi.dsi.fastutil.SafeMath.safeIntToByte(mappingFunction.applyAsInt(k));
		insert(-pos - 1, k, newValue);
		return newValue;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte computeIfAbsentNullable(final byte k,
			final java.util.function.IntFunction<? extends Byte> mappingFunction) {
		java.util.Objects.requireNonNull(mappingFunction);
		final int pos = find(k);
		if (pos >= 0)
			return value[pos];
		final Byte newValue = mappingFunction.apply(k);
		if (newValue == null)
			return defRetValue;
		final byte v = (newValue).byteValue();
		insert(-pos - 1, k, v);
		return v;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte computeIfPresent(final byte k,
			final java.util.function.BiFunction<? super Byte, ? super Byte, ? extends Byte> remappingFunction) {
		java.util.Objects.requireNonNull(remappingFunction);
		final int pos = find(k);
		if (pos < 0)
			return defRetValue;
		final Byte newValue = remappingFunction.apply(Byte.valueOf(k), Byte.valueOf(value[pos]));
		if (newValue == null) {
			if (((k) == ((byte) 0)))
				removeNullEntry();
			else
				removeEntry(pos);
			return defRetValue;
		}
		return value[pos] = (newValue).byteValue();
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte compute(final byte k,
			final java.util.function.BiFunction<? super Byte, ? super Byte, ? extends Byte> remappingFunction) {
		java.util.Objects.requireNonNull(remappingFunction);
		final int pos = find(k);
		final Byte newValue = remappingFunction.apply(Byte.valueOf(k), pos >= 0 ? Byte.valueOf(value[pos]) : null);
		if (newValue == null) {
			if (pos >= 0) {
				if (((k) == ((byte) 0)))
					removeNullEntry();
				else
					removeEntry(pos);
			}
			return defRetValue;
		}
		byte newVal = (newValue).byteValue();
		if (pos < 0) {
			insert(-pos - 1, k, newVal);
			return newVal;
		}
		return value[pos] = newVal;
	}
	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public byte merge(final byte k, final byte v,
			final java.util.function.BiFunction<? super Byte, ? super Byte, ? extends Byte> remappingFunction) {
		java.util.Objects.requireNonNull(remappingFunction);
		final int pos = find(k);
		if (pos < 0) {
			insert(-pos - 1, k, v);
			return v;
		}
		final Byte newValue = remappingFunction.apply(Byte.valueOf(value[pos]), Byte.valueOf(v));
		if (newValue == null) {
			if (((k) == ((byte) 0)))
				removeNullEntry();
			else
				removeEntry(pos);
			return defRetValue;
		}
		return value[pos] = (newValue).byteValue();
	}
	/*
	 * Removes all elements from this map.
	 *
	 * <p>To increase object reuse, this method does not change the table size. If
	 * you want to reduce the table size, you must use {@link #trim()}.
	 *
	 */
	@Override
	public void clear() {
		if (size == 0)
			return;
		size = 0;
		containsNullKey = false;
		Arrays.fill(key, ((byte) 0));
		first = last = -1;
	}
	@Override
	public int size() {
		return size;
	}
	@Override
	public boolean isEmpty() {
		return size == 0;
	}
	
The entry class for a hash map does not record key and value, but rather the position in the hash table of the corresponding entry. This is necessary so that calls to Entry.setValue(Object) are reflected in the map /**
	 * The entry class for a hash map does not record key and value, but rather the
	 * position in the hash table of the corresponding entry. This is necessary so
	 * that calls to {@link java.util.Map.Entry#setValue(Object)} are reflected in
	 * the map
	 */
	final class MapEntry implements Byte2ByteMap.Entry, Map.Entry<Byte, Byte> {
		// The table index this entry refers to, or -1 if this entry has been deleted.
		int index;
		MapEntry(final int index) {
			this.index = index;
		}
		MapEntry() {
		}
		@Override
		public byte getByteKey() {
			return key[index];
		}
		@Override
		public byte getByteValue() {
			return value[index];
		}
		@Override
		public byte setValue(final byte v) {
			final byte oldValue = value[index];
			value[index] = v;
			return oldValue;
		}
		
{@inheritDoc}
Deprecated:
Please use the corresponding type-specific method instead./**
		 * {@inheritDoc}
		 * 
		 * @deprecated Please use the corresponding type-specific method instead.
		 */
		@Deprecated
		@Override
		public Byte getKey() {
			return Byte.valueOf(key[index]);
		}
		
{@inheritDoc}
Deprecated:
Please use the corresponding type-specific method instead./**
		 * {@inheritDoc}
		 * 
		 * @deprecated Please use the corresponding type-specific method instead.
		 */
		@Deprecated
		@Override
		public Byte getValue() {
			return Byte.valueOf(value[index]);
		}
		
{@inheritDoc}
Deprecated:
Please use the corresponding type-specific method instead./**
		 * {@inheritDoc}
		 * 
		 * @deprecated Please use the corresponding type-specific method instead.
		 */
		@Deprecated
		@Override
		public Byte setValue(final Byte v) {
			return Byte.valueOf(setValue((v).byteValue()));
		}
		@SuppressWarnings("unchecked")
		@Override
		public boolean equals(final Object o) {
			if (!(o instanceof Map.Entry))
				return false;
			Map.Entry<Byte, Byte> e = (Map.Entry<Byte, Byte>) o;
			return ((key[index]) == ((e.getKey()).byteValue())) && ((value[index]) == ((e.getValue()).byteValue()));
		}
		@Override
		public int hashCode() {
			return (key[index]) ^ (value[index]);
		}
		@Override
		public String toString() {
			return key[index] + "=>" + value[index];
		}
	}
	
Modifies the link vector so that the given entry is removed. This method will complete in constant time. 
Params:
i – 
           the index of an entry./**
	 * Modifies the {@link #link} vector so that the given entry is removed. This
	 * method will complete in constant time.
	 *
	 * @param i
	 *            the index of an entry.
	 */
	protected void fixPointers(final int i) {
		if (size == 0) {
			first = last = -1;
			return;
		}
		if (first == i) {
			first = (int) link[i];
			if (0 <= first) {
				// Special case of SET_PREV(link[first], -1)
				link[first] |= (-1 & 0xFFFFFFFFL) << 32;
			}
			return;
		}
		if (last == i) {
			last = (int) (link[i] >>> 32);
			if (0 <= last) {
				// Special case of SET_NEXT(link[last], -1)
				link[last] |= -1 & 0xFFFFFFFFL;
			}
			return;
		}
		final long linki = link[i];
		final int prev = (int) (linki >>> 32);
		final int next = (int) linki;
		link[prev] ^= ((link[prev] ^ (linki & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
		link[next] ^= ((link[next] ^ (linki & 0xFFFFFFFF00000000L)) & 0xFFFFFFFF00000000L);
	}
	
Modifies the link vector for a shift from s to d. 

This method will complete in constant time.
Params:
s – 
           the source position.
d – 
           the destination position./**
	 * Modifies the {@link #link} vector for a shift from s to d.
	 * <p>
	 * This method will complete in constant time.
	 *
	 * @param s
	 *            the source position.
	 * @param d
	 *            the destination position.
	 */
	protected void fixPointers(int s, int d) {
		if (size == 1) {
			first = last = d;
			// Special case of SET_UPPER_LOWER(link[d], -1, -1)
			link[d] = -1L;
			return;
		}
		if (first == s) {
			first = d;
			link[(int) link[s]] ^= ((link[(int) link[s]] ^ ((d & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
			link[d] = link[s];
			return;
		}
		if (last == s) {
			last = d;
			link[(int) (link[s] >>> 32)] ^= ((link[(int) (link[s] >>> 32)] ^ (d & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			link[d] = link[s];
			return;
		}
		final long links = link[s];
		final int prev = (int) (links >>> 32);
		final int next = (int) links;
		link[prev] ^= ((link[prev] ^ (d & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
		link[next] ^= ((link[next] ^ ((d & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
		link[d] = links;
	}
	
Returns the first key of this map in iteration order.
Returns:
the first key in iteration order./**
	 * Returns the first key of this map in iteration order.
	 *
	 * @return the first key in iteration order.
	 */
	@Override
	public byte firstByteKey() {
		if (size == 0)
			throw new NoSuchElementException();
		return key[first];
	}
	
Returns the last key of this map in iteration order.
Returns:
the last key in iteration order./**
	 * Returns the last key of this map in iteration order.
	 *
	 * @return the last key in iteration order.
	 */
	@Override
	public byte lastByteKey() {
		if (size == 0)
			throw new NoSuchElementException();
		return key[last];
	}
	
{@inheritDoc}
 This implementation just throws an UnsupportedOperationException. /**
	 * {@inheritDoc}
	 * <p>
	 * This implementation just throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public Byte2ByteSortedMap tailMap(byte from) {
		throw new UnsupportedOperationException();
	}
	
{@inheritDoc}
 This implementation just throws an UnsupportedOperationException. /**
	 * {@inheritDoc}
	 * <p>
	 * This implementation just throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public Byte2ByteSortedMap headMap(byte to) {
		throw new UnsupportedOperationException();
	}
	
{@inheritDoc}
 This implementation just throws an UnsupportedOperationException. /**
	 * {@inheritDoc}
	 * <p>
	 * This implementation just throws an {@link UnsupportedOperationException}.
	 */
	@Override
	public Byte2ByteSortedMap subMap(byte from, byte to) {
		throw new UnsupportedOperationException();
	}
	
{@inheritDoc}
 This implementation just returns null. /**
	 * {@inheritDoc}
	 * <p>
	 * This implementation just returns {@code null}.
	 */
	@Override
	public ByteComparator comparator() {
		return null;
	}
	
A list iterator over a linked map.

This class provides a list iterator over a linked hash map. The constructor
runs in constant time.
/**
	 * A list iterator over a linked map.
	 *
	 * <p>
	 * This class provides a list iterator over a linked hash map. The constructor
	 * runs in constant time.
	 */
	private class MapIterator {
		
The entry that will be returned by the next call to ListIterator.previous() (or null if no previous entry exists). /**
		 * The entry that will be returned by the next call to
		 * {@link java.util.ListIterator#previous()} (or {@code null} if no previous
		 * entry exists).
		 */
		int prev = -1;
		
The entry that will be returned by the next call to ListIterator.next() (or null if no next entry exists). /**
		 * The entry that will be returned by the next call to
		 * {@link java.util.ListIterator#next()} (or {@code null} if no next entry
		 * exists).
		 */
		int next = -1;
		
The last entry that was returned (or -1 if we did not iterate or used Iterator.remove()). /**
		 * The last entry that was returned (or -1 if we did not iterate or used
		 * {@link java.util.Iterator#remove()}).
		 */
		int curr = -1;
		
The current index (in the sense of a ListIterator). Note that this value is not meaningful when this iterator has been created using the nonempty constructor. /**
		 * The current index (in the sense of a {@link java.util.ListIterator}). Note
		 * that this value is not meaningful when this iterator has been created using
		 * the nonempty constructor.
		 */
		int index = -1;
		protected MapIterator() {
			next = first;
			index = 0;
		}
		private MapIterator(final byte from) {
			if (((from) == ((byte) 0))) {
				if (Byte2ByteLinkedOpenHashMap.this.containsNullKey) {
					next = (int) link[n];
					prev = n;
					return;
				} else
					throw new NoSuchElementException("The key " + from + " does not belong to this map.");
			}
			if (((key[last]) == (from))) {
				prev = last;
				index = size;
				return;
			}
			// The starting point.
			int pos = (it.unimi.dsi.fastutil.HashCommon.mix((from))) & mask;
			// There's always an unused entry.
			while (!((key[pos]) == ((byte) 0))) {
				if (((key[pos]) == (from))) {
					// Note: no valid index known.
					next = (int) link[pos];
					prev = pos;
					return;
				}
				pos = (pos + 1) & mask;
			}
			throw new NoSuchElementException("The key " + from + " does not belong to this map.");
		}
		public boolean hasNext() {
			return next != -1;
		}
		public boolean hasPrevious() {
			return prev != -1;
		}
		private final void ensureIndexKnown() {
			if (index >= 0)
				return;
			if (prev == -1) {
				index = 0;
				return;
			}
			if (next == -1) {
				index = size;
				return;
			}
			int pos = first;
			index = 1;
			while (pos != prev) {
				pos = (int) link[pos];
				index++;
			}
		}
		public int nextIndex() {
			ensureIndexKnown();
			return index;
		}
		public int previousIndex() {
			ensureIndexKnown();
			return index - 1;
		}
		public int nextEntry() {
			if (!hasNext())
				throw new NoSuchElementException();
			curr = next;
			next = (int) link[curr];
			prev = curr;
			if (index >= 0)
				index++;
			return curr;
		}
		public int previousEntry() {
			if (!hasPrevious())
				throw new NoSuchElementException();
			curr = prev;
			prev = (int) (link[curr] >>> 32);
			next = curr;
			if (index >= 0)
				index--;
			return curr;
		}
		public void remove() {
			ensureIndexKnown();
			if (curr == -1)
				throw new IllegalStateException();
			if (curr == prev) {
				/*
				 * If the last operation was a next(), we are removing an entry that preceeds
				 * the current index, and thus we must decrement it.
				 */
				index--;
				prev = (int) (link[curr] >>> 32);
			} else
				next = (int) link[curr];
			size--;
			/*
			 * Now we manually fix the pointers. Because of our knowledge of next and prev,
			 * this is going to be faster than calling fixPointers().
			 */
			if (prev == -1)
				first = next;
			else
				link[prev] ^= ((link[prev] ^ (next & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
			if (next == -1)
				last = prev;
			else
				link[next] ^= ((link[next] ^ ((prev & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
			int last, slot, pos = curr;
			curr = -1;
			if (pos == n) {
				Byte2ByteLinkedOpenHashMap.this.containsNullKey = false;
			} else {
				byte curr;
				final byte[] key = Byte2ByteLinkedOpenHashMap.this.key;
				// We have to horribly duplicate the shiftKeys() code because we need to update
				// next/prev.
				for (;;) {
					pos = ((last = pos) + 1) & mask;
					for (;;) {
						if (((curr = key[pos]) == ((byte) 0))) {
							key[last] = ((byte) 0);
							return;
						}
						slot = (it.unimi.dsi.fastutil.HashCommon.mix((curr))) & mask;
						if (last <= pos ? last >= slot || slot > pos : last >= slot && slot > pos)
							break;
						pos = (pos + 1) & mask;
					}
					key[last] = curr;
					value[last] = value[pos];
					if (next == pos)
						next = last;
					if (prev == pos)
						prev = last;
					fixPointers(pos, last);
				}
			}
		}
		public int skip(final int n) {
			int i = n;
			while (i-- != 0 && hasNext())
				nextEntry();
			return n - i - 1;
		}
		public int back(final int n) {
			int i = n;
			while (i-- != 0 && hasPrevious())
				previousEntry();
			return n - i - 1;
		}
		public void set(@SuppressWarnings("unused") Byte2ByteMap.Entry ok) {
			throw new UnsupportedOperationException();
		}
		public void add(@SuppressWarnings("unused") Byte2ByteMap.Entry ok) {
			throw new UnsupportedOperationException();
		}
	}
	private class EntryIterator extends MapIterator implements ObjectListIterator<Byte2ByteMap.Entry> {
		private MapEntry entry;
		public EntryIterator() {
		}
		public EntryIterator(byte from) {
			super(from);
		}
		@Override
		public MapEntry next() {
			return entry = new MapEntry(nextEntry());
		}
		@Override
		public MapEntry previous() {
			return entry = new MapEntry(previousEntry());
		}
		@Override
		public void remove() {
			super.remove();
			entry.index = -1; // You cannot use a deleted entry.
		}
	}
	private class FastEntryIterator extends MapIterator implements ObjectListIterator<Byte2ByteMap.Entry> {
		final MapEntry entry = new MapEntry();
		public FastEntryIterator() {
		}
		public FastEntryIterator(byte from) {
			super(from);
		}
		@Override
		public MapEntry next() {
			entry.index = nextEntry();
			return entry;
		}
		@Override
		public MapEntry previous() {
			entry.index = previousEntry();
			return entry;
		}
	}
	private final class MapEntrySet extends AbstractObjectSortedSet<Byte2ByteMap.Entry> implements FastSortedEntrySet {
		@Override
		public ObjectBidirectionalIterator<Byte2ByteMap.Entry> iterator() {
			return new EntryIterator();
		}
		@Override
		public Comparator<? super Byte2ByteMap.Entry> comparator() {
			return null;
		}
		@Override
		public ObjectSortedSet<Byte2ByteMap.Entry> subSet(Byte2ByteMap.Entry fromElement,
				Byte2ByteMap.Entry toElement) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ObjectSortedSet<Byte2ByteMap.Entry> headSet(Byte2ByteMap.Entry toElement) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ObjectSortedSet<Byte2ByteMap.Entry> tailSet(Byte2ByteMap.Entry fromElement) {
			throw new UnsupportedOperationException();
		}
		@Override
		public Byte2ByteMap.Entry first() {
			if (size == 0)
				throw new NoSuchElementException();
			return new MapEntry(Byte2ByteLinkedOpenHashMap.this.first);
		}
		@Override
		public Byte2ByteMap.Entry last() {
			if (size == 0)
				throw new NoSuchElementException();
			return new MapEntry(Byte2ByteLinkedOpenHashMap.this.last);
		}
		@Override

		public boolean contains(final Object o) {
			if (!(o instanceof Map.Entry))
				return false;
			final Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
			if (e.getKey() == null || !(e.getKey() instanceof Byte))
				return false;
			if (e.getValue() == null || !(e.getValue() instanceof Byte))
				return false;
			final byte k = ((Byte) (e.getKey())).byteValue();
			final byte v = ((Byte) (e.getValue())).byteValue();
			if (((k) == ((byte) 0)))
				return Byte2ByteLinkedOpenHashMap.this.containsNullKey && ((value[n]) == (v));
			byte curr;
			final byte[] key = Byte2ByteLinkedOpenHashMap.this.key;
			int pos;
			// The starting point.
			if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
				return false;
			if (((k) == (curr)))
				return ((value[pos]) == (v));
			// There's always an unused entry.
			while (true) {
				if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
					return false;
				if (((k) == (curr)))
					return ((value[pos]) == (v));
			}
		}
		@Override

		public boolean remove(final Object o) {
			if (!(o instanceof Map.Entry))
				return false;
			final Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
			if (e.getKey() == null || !(e.getKey() instanceof Byte))
				return false;
			if (e.getValue() == null || !(e.getValue() instanceof Byte))
				return false;
			final byte k = ((Byte) (e.getKey())).byteValue();
			final byte v = ((Byte) (e.getValue())).byteValue();
			if (((k) == ((byte) 0))) {
				if (containsNullKey && ((value[n]) == (v))) {
					removeNullEntry();
					return true;
				}
				return false;
			}
			byte curr;
			final byte[] key = Byte2ByteLinkedOpenHashMap.this.key;
			int pos;
			// The starting point.
			if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask]) == ((byte) 0)))
				return false;
			if (((curr) == (k))) {
				if (((value[pos]) == (v))) {
					removeEntry(pos);
					return true;
				}
				return false;
			}
			while (true) {
				if (((curr = key[pos = (pos + 1) & mask]) == ((byte) 0)))
					return false;
				if (((curr) == (k))) {
					if (((value[pos]) == (v))) {
						removeEntry(pos);
						return true;
					}
				}
			}
		}
		@Override
		public int size() {
			return size;
		}
		@Override
		public void clear() {
			Byte2ByteLinkedOpenHashMap.this.clear();
		}
		
Returns a type-specific list iterator on the elements in this set, starting
from a given element of the set. Please see the class documentation for
implementation details.
Params:
from – 
           an element to start from.
Throws:
IllegalArgumentException –  if from does not belong to the set.
Returns:
a type-specific list iterator starting at the given element./**
		 * Returns a type-specific list iterator on the elements in this set, starting
		 * from a given element of the set. Please see the class documentation for
		 * implementation details.
		 *
		 * @param from
		 *            an element to start from.
		 * @return a type-specific list iterator starting at the given element.
		 * @throws IllegalArgumentException
		 *             if {@code from} does not belong to the set.
		 */
		@Override
		public ObjectListIterator<Byte2ByteMap.Entry> iterator(final Byte2ByteMap.Entry from) {
			return new EntryIterator(from.getByteKey());
		}
		
Returns a type-specific fast list iterator on the elements in this set,
starting from the first element. Please see the class documentation for
implementation details.
Returns:
a type-specific list iterator starting at the first element./**
		 * Returns a type-specific fast list iterator on the elements in this set,
		 * starting from the first element. Please see the class documentation for
		 * implementation details.
		 *
		 * @return a type-specific list iterator starting at the first element.
		 */
		@Override
		public ObjectListIterator<Byte2ByteMap.Entry> fastIterator() {
			return new FastEntryIterator();
		}
		
Returns a type-specific fast list iterator on the elements in this set,
starting from a given element of the set. Please see the class documentation
for implementation details.
Params:
from – 
           an element to start from.
Throws:
IllegalArgumentException –  if from does not belong to the set.
Returns:
a type-specific list iterator starting at the given element./**
		 * Returns a type-specific fast list iterator on the elements in this set,
		 * starting from a given element of the set. Please see the class documentation
		 * for implementation details.
		 *
		 * @param from
		 *            an element to start from.
		 * @return a type-specific list iterator starting at the given element.
		 * @throws IllegalArgumentException
		 *             if {@code from} does not belong to the set.
		 */
		@Override
		public ObjectListIterator<Byte2ByteMap.Entry> fastIterator(final Byte2ByteMap.Entry from) {
			return new FastEntryIterator(from.getByteKey());
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		public void forEach(final Consumer<? super Byte2ByteMap.Entry> consumer) {
			for (int i = size, curr, next = first; i-- != 0;) {
				curr = next;
				next = (int) link[curr];
				consumer.accept(new AbstractByte2ByteMap.BasicEntry(key[curr], value[curr]));
			}
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		public void fastForEach(final Consumer<? super Byte2ByteMap.Entry> consumer) {
			final AbstractByte2ByteMap.BasicEntry entry = new AbstractByte2ByteMap.BasicEntry();
			for (int i = size, curr, next = first; i-- != 0;) {
				curr = next;
				next = (int) link[curr];
				entry.key = key[curr];
				entry.value = value[curr];
				consumer.accept(entry);
			}
		}
	}
	@Override
	public FastSortedEntrySet byte2ByteEntrySet() {
		if (entries == null)
			entries = new MapEntrySet();
		return entries;
	}
	
An iterator on keys.
 We simply override the ListIterator.next()/ListIterator.previous() methods (and possibly their type-specific counterparts) so that they return keys instead of entries. /**
	 * An iterator on keys.
	 *
	 * <p>
	 * We simply override the
	 * {@link java.util.ListIterator#next()}/{@link java.util.ListIterator#previous()}
	 * methods (and possibly their type-specific counterparts) so that they return
	 * keys instead of entries.
	 */
	private final class KeyIterator extends MapIterator implements ByteListIterator {
		public KeyIterator(final byte k) {
			super(k);
		}
		@Override
		public byte previousByte() {
			return key[previousEntry()];
		}
		public KeyIterator() {
			super();
		}
		@Override
		public byte nextByte() {
			return key[nextEntry()];
		}
	}
	private final class KeySet extends AbstractByteSortedSet {
		@Override
		public ByteListIterator iterator(final byte from) {
			return new KeyIterator(from);
		}
		@Override
		public ByteListIterator iterator() {
			return new KeyIterator();
		}
		
{@inheritDoc} /** {@inheritDoc} */
		@Override
		public void forEach(final java.util.function.IntConsumer consumer) {
			if (containsNullKey)
				consumer.accept(key[n]);
			for (int pos = n; pos-- != 0;) {
				final byte k = key[pos];
				if (!((k) == ((byte) 0)))
					consumer.accept(k);
			}
		}
		@Override
		public int size() {
			return size;
		}
		@Override
		public boolean contains(byte k) {
			return containsKey(k);
		}
		@Override
		public boolean remove(byte k) {
			final int oldSize = size;
			Byte2ByteLinkedOpenHashMap.this.remove(k);
			return size != oldSize;
		}
		@Override
		public void clear() {
			Byte2ByteLinkedOpenHashMap.this.clear();
		}
		@Override
		public byte firstByte() {
			if (size == 0)
				throw new NoSuchElementException();
			return key[first];
		}
		@Override
		public byte lastByte() {
			if (size == 0)
				throw new NoSuchElementException();
			return key[last];
		}
		@Override
		public ByteComparator comparator() {
			return null;
		}
		@Override
		public ByteSortedSet tailSet(byte from) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ByteSortedSet headSet(byte to) {
			throw new UnsupportedOperationException();
		}
		@Override
		public ByteSortedSet subSet(byte from, byte to) {
			throw new UnsupportedOperationException();
		}
	}
	@Override
	public ByteSortedSet keySet() {
		if (keys == null)
			keys = new KeySet();
		return keys;
	}
	
An iterator on values.
 We simply override the ListIterator.next()/ListIterator.previous() methods (and possibly their type-specific counterparts) so that they return values instead of entries. /**
	 * An iterator on values.
	 *
	 * <p>
	 * We simply override the
	 * {@link java.util.ListIterator#next()}/{@link java.util.ListIterator#previous()}
	 * methods (and possibly their type-specific counterparts) so that they return
	 * values instead of entries.
	 */
	private final class ValueIterator extends MapIterator implements ByteListIterator {
		@Override
		public byte previousByte() {
			return value[previousEntry()];
		}
		public ValueIterator() {
			super();
		}
		@Override
		public byte nextByte() {
			return value[nextEntry()];
		}
	}
	@Override
	public ByteCollection values() {
		if (values == null)
			values = new AbstractByteCollection() {
				@Override
				public ByteIterator iterator() {
					return new ValueIterator();
				}
				@Override
				public int size() {
					return size;
				}
				@Override
				public boolean contains(byte v) {
					return containsValue(v);
				}
				@Override
				public void clear() {
					Byte2ByteLinkedOpenHashMap.this.clear();
				}
				
{@inheritDoc} /** {@inheritDoc} */
				@Override
				public void forEach(final java.util.function.IntConsumer consumer) {
					if (containsNullKey)
						consumer.accept(value[n]);
					for (int pos = n; pos-- != 0;)
						if (!((key[pos]) == ((byte) 0)))
							consumer.accept(value[pos]);
				}
			};
		return values;
	}
	
Rehashes the map, making the table as small as possible.

This method rehashes the table to the smallest size satisfying the load
factor. It can be used when the set will not be changed anymore, so to
optimize access speed and size.

If the table size is already the minimum possible, this method does nothing.
See Also:
trim(int)
Returns:
true if there was enough memory to trim the map./**
	 * Rehashes the map, making the table as small as possible.
	 *
	 * <p>
	 * This method rehashes the table to the smallest size satisfying the load
	 * factor. It can be used when the set will not be changed anymore, so to
	 * optimize access speed and size.
	 *
	 * <p>
	 * If the table size is already the minimum possible, this method does nothing.
	 *
	 * @return true if there was enough memory to trim the map.
	 * @see #trim(int)
	 */
	public boolean trim() {
		return trim(size);
	}
	
Rehashes this map if the table is too large.

Let N be the smallest table size that can hold
max(n,size()) entries, still satisfying the load
factor. If the current table size is smaller than or equal to N,
this method does nothing. Otherwise, it rehashes this map in a table of size
N.
 This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps. 
Params:
n – 
           the threshold for the trimming.
See Also:
trim()
Returns:
true if there was enough memory to trim the map./**
	 * Rehashes this map if the table is too large.
	 *
	 * <p>
	 * Let <var>N</var> be the smallest table size that can hold
	 * <code>max(n,{@link #size()})</code> entries, still satisfying the load
	 * factor. If the current table size is smaller than or equal to <var>N</var>,
	 * this method does nothing. Otherwise, it rehashes this map in a table of size
	 * <var>N</var>.
	 *
	 * <p>
	 * This method is useful when reusing maps. {@linkplain #clear() Clearing a map}
	 * leaves the table size untouched. If you are reusing a map many times, you can
	 * call this method with a typical size to avoid keeping around a very large
	 * table just because of a few large transient maps.
	 *
	 * @param n
	 *            the threshold for the trimming.
	 * @return true if there was enough memory to trim the map.
	 * @see #trim()
	 */
	public boolean trim(final int n) {
		final int l = HashCommon.nextPowerOfTwo((int) Math.ceil(n / f));
		if (l >= this.n || size > maxFill(l, f))
			return true;
		try {
			rehash(l);
		} catch (OutOfMemoryError cantDoIt) {
			return false;
		}
		return true;
	}
	
Rehashes the map.

This method implements the basic rehashing strategy, and may be overridden by
subclasses implementing different rehashing strategies (e.g., disk-based
rehashing). However, you should not override this method unless you
understand the internal workings of this class.
Params:
newN – 
           the new size/**
	 * Rehashes the map.
	 *
	 * <p>
	 * This method implements the basic rehashing strategy, and may be overridden by
	 * subclasses implementing different rehashing strategies (e.g., disk-based
	 * rehashing). However, you should not override this method unless you
	 * understand the internal workings of this class.
	 *
	 * @param newN
	 *            the new size
	 */

	protected void rehash(final int newN) {
		final byte key[] = this.key;
		final byte value[] = this.value;
		final int mask = newN - 1; // Note that this is used by the hashing macro
		final byte newKey[] = new byte[newN + 1];
		final byte newValue[] = new byte[newN + 1];
		int i = first, prev = -1, newPrev = -1, t, pos;
		final long link[] = this.link;
		final long newLink[] = new long[newN + 1];
		first = -1;
		for (int j = size; j-- != 0;) {
			if (((key[i]) == ((byte) 0)))
				pos = newN;
			else {
				pos = (it.unimi.dsi.fastutil.HashCommon.mix((key[i]))) & mask;
				while (!((newKey[pos]) == ((byte) 0)))
					pos = (pos + 1) & mask;
			}
			newKey[pos] = key[i];
			newValue[pos] = value[i];
			if (prev != -1) {
				newLink[newPrev] ^= ((newLink[newPrev] ^ (pos & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
				newLink[pos] ^= ((newLink[pos] ^ ((newPrev & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
				newPrev = pos;
			} else {
				newPrev = first = pos;
				// Special case of SET(newLink[pos], -1, -1);
				newLink[pos] = -1L;
			}
			t = i;
			i = (int) link[i];
			prev = t;
		}
		this.link = newLink;
		this.last = newPrev;
		if (newPrev != -1)
			// Special case of SET_NEXT(newLink[newPrev], -1);
			newLink[newPrev] |= -1 & 0xFFFFFFFFL;
		n = newN;
		this.mask = mask;
		maxFill = maxFill(n, f);
		this.key = newKey;
		this.value = newValue;
	}
	
Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the
map, however, is not cloned. Note that this makes a difference only for
object keys.
Returns:
a deep copy of this map./**
	 * Returns a deep copy of this map.
	 *
	 * <p>
	 * This method performs a deep copy of this hash map; the data stored in the
	 * map, however, is not cloned. Note that this makes a difference only for
	 * object keys.
	 *
	 * @return a deep copy of this map.
	 */
	@Override

	public Byte2ByteLinkedOpenHashMap clone() {
		Byte2ByteLinkedOpenHashMap c;
		try {
			c = (Byte2ByteLinkedOpenHashMap) super.clone();
		} catch (CloneNotSupportedException cantHappen) {
			throw new InternalError();
		}
		c.keys = null;
		c.values = null;
		c.entries = null;
		c.containsNullKey = containsNullKey;
		c.key = key.clone();
		c.value = value.clone();
		c.link = link.clone();
		return c;
	}
	
Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method. 
Returns:
a hash code for this map./**
	 * Returns a hash code for this map.
	 *
	 * This method overrides the generic method provided by the superclass. Since
	 * {@code equals()} is not overriden, it is important that the value returned by
	 * this method is the same value as the one returned by the overriden method.
	 *
	 * @return a hash code for this map.
	 */
	@Override
	public int hashCode() {
		int h = 0;
		for (int j = realSize(), i = 0, t = 0; j-- != 0;) {
			while (((key[i]) == ((byte) 0)))
				i++;
			t = (key[i]);
			t ^= (value[i]);
			h += t;
			i++;
		}
		// Zero / null keys have hash zero.
		if (containsNullKey)
			h += (value[n]);
		return h;
	}
	private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
		final byte key[] = this.key;
		final byte value[] = this.value;
		final MapIterator i = new MapIterator();
		s.defaultWriteObject();
		for (int j = size, e; j-- != 0;) {
			e = i.nextEntry();
			s.writeByte(key[e]);
			s.writeByte(value[e]);
		}
	}

	private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
		s.defaultReadObject();
		n = arraySize(size, f);
		maxFill = maxFill(n, f);
		mask = n - 1;
		final byte key[] = this.key = new byte[n + 1];
		final byte value[] = this.value = new byte[n + 1];
		final long link[] = this.link = new long[n + 1];
		int prev = -1;
		first = last = -1;
		byte k;
		byte v;
		for (int i = size, pos; i-- != 0;) {
			k = s.readByte();
			v = s.readByte();
			if (((k) == ((byte) 0))) {
				pos = n;
				containsNullKey = true;
			} else {
				pos = (it.unimi.dsi.fastutil.HashCommon.mix((k))) & mask;
				while (!((key[pos]) == ((byte) 0)))
					pos = (pos + 1) & mask;
			}
			key[pos] = k;
			value[pos] = v;
			if (first != -1) {
				link[prev] ^= ((link[prev] ^ (pos & 0xFFFFFFFFL)) & 0xFFFFFFFFL);
				link[pos] ^= ((link[pos] ^ ((prev & 0xFFFFFFFFL) << 32)) & 0xFFFFFFFF00000000L);
				prev = pos;
			} else {
				prev = first = pos;
				// Special case of SET_PREV(newLink[pos], -1);
				link[pos] |= (-1L & 0xFFFFFFFFL) << 32;
			}
		}
		last = prev;
		if (prev != -1)
			// Special case of SET_NEXT(link[prev], -1);
			link[prev] |= -1 & 0xFFFFFFFFL;
		if (ASSERTS)
			checkTable();
	}
	private void checkTable() {
	}
}