/*
	* 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.ints;
import static it.unimi.dsi.fastutil.BigArrays.copy;
import static it.unimi.dsi.fastutil.BigArrays.fill;
import static it.unimi.dsi.fastutil.BigArrays.set;
import it.unimi.dsi.fastutil.BigArrays;
import it.unimi.dsi.fastutil.Hash;
import it.unimi.dsi.fastutil.Size64;
import it.unimi.dsi.fastutil.HashCommon;
import static it.unimi.dsi.fastutil.HashCommon.bigArraySize;
import static it.unimi.dsi.fastutil.HashCommon.maxFill;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
A type-specific hash big set with with a fast, small-footprint
implementation.
 Instances of this class use a hash table to represent a big set: the number of elements in the set is limited only by the amount of core memory. The table (backed by a big array) 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 sets 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. 

The methods of this class are about 30% slower than those of the
corresponding non-big set.
See Also:
Hash
HashCommon/**
 * A type-specific hash big set with with a fast, small-footprint
 * implementation.
 *
 * <p>
 * Instances of this class use a hash table to represent a big set: the number
 * of elements in the set is limited only by the amount of core memory. The
 * table (backed by a {@linkplain it.unimi.dsi.fastutil.BigArrays big array}) 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 sets 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>
 * The methods of this class are about 30% slower than those of the
 * corresponding non-big set.
 *
 * @see Hash
 * @see HashCommon
 */
public class IntOpenHashBigSet extends AbstractIntSet implements java.io.Serializable, Cloneable, Hash, Size64 {
	private static final long serialVersionUID = 0L;
	private static final boolean ASSERTS = false;
	
The big array of keys. /** The big array of keys. */
	protected transient int[][] key;
	
The mask for wrapping a position counter. /** The mask for wrapping a position counter. */
	protected transient long mask;
	
The mask for wrapping a segment counter. /** The mask for wrapping a segment counter. */
	protected transient int segmentMask;
	
The mask for wrapping a base counter. /** The mask for wrapping a base counter. */
	protected transient int baseMask;
	
Whether this set contains the null key. /** Whether this set contains the null key. */
	protected transient boolean containsNull;
	
The current table size (always a power of 2). /** The current table size (always a power of 2). */
	protected transient long 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 long 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 long minN;
	
The acceptable load factor. /** The acceptable load factor. */
	protected final float f;
	
Number of entries in the set. /** Number of entries in the set. */
	protected long size;
	
Initialises the mask values. /** Initialises the mask values. */
	private void initMasks() {
		mask = n - 1;
		/*
		 * Note that either we have more than one segment, and in this case all segments
		 * are BigArrays.SEGMENT_SIZE long, or we have exactly one segment whose length
		 * is a power of two.
		 */
		segmentMask = key[0].length - 1;
		baseMask = key.length - 1;
	}
	
Creates a new hash big set.
 The actual table size will be the least power of two greater than expected/f. 
Params:
expected – 
           the expected number of elements in the set.
f – 
           the load factor./**
	 * Creates a new hash big set.
	 *
	 * <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 set.
	 * @param f
	 *            the load factor.
	 */

	public IntOpenHashBigSet(final long 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 (n < 0)
			throw new IllegalArgumentException("The expected number of elements must be nonnegative");
		this.f = f;
		minN = n = bigArraySize(expected, f);
		maxFill = maxFill(n, f);
		key = IntBigArrays.newBigArray(n);
		initMasks();
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor. 
Params:
expected – 
           the expected number of elements in the hash big set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor.
	 *
	 * @param expected
	 *            the expected number of elements in the hash big set.
	 */
	public IntOpenHashBigSet(final long expected) {
		this(expected, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set with initial expected Hash.DEFAULT_INITIAL_SIZE elements and Hash.DEFAULT_LOAD_FACTOR as load factor. /**
	 * Creates a new hash big set with initial expected
	 * {@link Hash#DEFAULT_INITIAL_SIZE} elements and
	 * {@link Hash#DEFAULT_LOAD_FACTOR} as load factor.
	 */
	public IntOpenHashBigSet() {
		this(DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set copying a given collection.
Params:
c –  a Collection to be copied into the new hash big set.
f – 
           the load factor./**
	 * Creates a new hash big set copying a given collection.
	 *
	 * @param c
	 *            a {@link Collection} to be copied into the new hash big set.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final Collection<? extends Integer> c, final float f) {
		this(c.size(), f);
		addAll(c);
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given collection. 
Params:
c –  a Collection to be copied into the new hash big set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor copying a given collection.
	 *
	 * @param c
	 *            a {@link Collection} to be copied into the new hash big set.
	 */
	public IntOpenHashBigSet(final Collection<? extends Integer> c) {
		this(c, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set copying a given type-specific collection.
Params:
c – 
           a type-specific collection to be copied into the new hash big set.
f – 
           the load factor./**
	 * Creates a new hash big set copying a given type-specific collection.
	 *
	 * @param c
	 *            a type-specific collection to be copied into the new hash big set.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final IntCollection c, final float f) {
		this(c.size(), f);
		addAll(c);
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific collection. 
Params:
c – 
           a type-specific collection to be copied into the new hash big set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor copying a given type-specific collection.
	 *
	 * @param c
	 *            a type-specific collection to be copied into the new hash big set.
	 */
	public IntOpenHashBigSet(final IntCollection c) {
		this(c, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set using elements provided by a type-specific
iterator.
Params:
i – 
           a type-specific iterator whose elements will fill the new hash big
           set.
f – 
           the load factor./**
	 * Creates a new hash big set using elements provided by a type-specific
	 * iterator.
	 *
	 * @param i
	 *            a type-specific iterator whose elements will fill the new hash big
	 *            set.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final IntIterator i, final float f) {
		this(DEFAULT_INITIAL_SIZE, f);
		while (i.hasNext())
			add(i.nextInt());
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by a type-specific iterator. 
Params:
i – 
           a type-specific iterator whose elements will fill the new hash big
           set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor using elements provided by a type-specific iterator.
	 *
	 * @param i
	 *            a type-specific iterator whose elements will fill the new hash big
	 *            set.
	 */
	public IntOpenHashBigSet(final IntIterator i) {
		this(i, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set using elements provided by an iterator.
Params:
i – 
           an iterator whose elements will fill the new hash big set.
f – 
           the load factor./**
	 * Creates a new hash big set using elements provided by an iterator.
	 *
	 * @param i
	 *            an iterator whose elements will fill the new hash big set.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final Iterator<?> i, final float f) {
		this(IntIterators.asIntIterator(i), f);
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor using elements provided by an iterator. 
Params:
i – 
           an iterator whose elements will fill the new hash big set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor using elements provided by an iterator.
	 *
	 * @param i
	 *            an iterator whose elements will fill the new hash big set.
	 */
	public IntOpenHashBigSet(final Iterator<?> i) {
		this(IntIterators.asIntIterator(i));
	}
	
Creates a new hash big set and fills it with the elements of a given array.
Params:
a – 
           an array whose elements will be used to fill the new hash big set.
offset – 
           the first element to use.
length – 
           the number of elements to use.
f – 
           the load factor./**
	 * Creates a new hash big set and fills it with the elements of a given array.
	 *
	 * @param a
	 *            an array whose elements will be used to fill the new hash big set.
	 * @param offset
	 *            the first element to use.
	 * @param length
	 *            the number of elements to use.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final int[] a, final int offset, final int length, final float f) {
		this(length < 0 ? 0 : length, f);
		IntArrays.ensureOffsetLength(a, offset, length);
		for (int i = 0; i < length; i++)
			add(a[offset + i]);
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor and fills it with the elements of a given array. 
Params:
a – 
           an array whose elements will be used to fill the new hash big set.
offset – 
           the first element to use.
length – 
           the number of elements to use./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor and fills it with the elements of a given array.
	 *
	 * @param a
	 *            an array whose elements will be used to fill the new hash big set.
	 * @param offset
	 *            the first element to use.
	 * @param length
	 *            the number of elements to use.
	 */
	public IntOpenHashBigSet(final int[] a, final int offset, final int length) {
		this(a, offset, length, DEFAULT_LOAD_FACTOR);
	}
	
Creates a new hash big set copying the elements of an array.
Params:
a – 
           an array to be copied into the new hash big set.
f – 
           the load factor./**
	 * Creates a new hash big set copying the elements of an array.
	 *
	 * @param a
	 *            an array to be copied into the new hash big set.
	 * @param f
	 *            the load factor.
	 */
	public IntOpenHashBigSet(final int[] a, final float f) {
		this(a, 0, a.length, f);
	}
	
Creates a new hash big set with Hash.DEFAULT_LOAD_FACTOR as load factor copying the elements of an array. 
Params:
a – 
           an array to be copied into the new hash big set./**
	 * Creates a new hash big set with {@link Hash#DEFAULT_LOAD_FACTOR} as load
	 * factor copying the elements of an array.
	 *
	 * @param a
	 *            an array to be copied into the new hash big set.
	 */
	public IntOpenHashBigSet(final int[] a) {
		this(a, DEFAULT_LOAD_FACTOR);
	}
	private long realSize() {
		return containsNull ? size - 1 : size;
	}
	private void ensureCapacity(final long capacity) {
		final long needed = bigArraySize(capacity, f);
		if (needed > n)
			rehash(needed);
	}
	@Override
	public boolean addAll(Collection<? extends Integer> c) {
		final long size = c instanceof Size64 ? ((Size64) c).size64() : c.size();
		// The resulting collection will be at least c.size() big
		if (f <= .5)
			ensureCapacity(size); // The resulting collection will be sized for c.size() elements
		else
			ensureCapacity(size64() + size); // The resulting collection will be sized for size() + c.size() elements
		return super.addAll(c);
	}
	@Override
	public boolean addAll(IntCollection c) {
		final long size = c instanceof Size64 ? ((Size64) c).size64() : c.size();
		if (f <= .5)
			ensureCapacity(size); // The resulting collection will be size for c.size() elements
		else
			ensureCapacity(size64() + size); // The resulting collection will be sized for size() + c.size() elements
		return super.addAll(c);
	}
	@Override
	public boolean add(final int k) {
		int displ, base;
		if (((k) == (0))) {
			if (containsNull)
				return false;
			containsNull = true;
		} else {
			int curr;
			final int[][] key = this.key;
			final long h = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((k))));
			// The starting point.
			if (!((curr = key[base = (int) ((h & mask) >>> BigArrays.SEGMENT_SHIFT)][displ = (int) (h
					& segmentMask)]) == (0))) {
				if (((curr) == (k)))
					return false;
				while (!((curr = key[base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0))
						& baseMask][displ]) == (0)))
					if (((curr) == (k)))
						return false;
			}
			key[base][displ] = k;
		}
		if (size++ >= maxFill)
			rehash(2 * n);
		if (ASSERTS)
			checkTable();
		return true;
	}
	
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(long pos) {
		// Shift entries with the same hash.
		long last, slot;
		final int[][] key = this.key;
		for (;;) {
			pos = ((last = pos) + 1) & mask;
			for (;;) {
				if (((BigArrays.get(key, pos)) == (0))) {
					set(key, last, (0));
					return;
				}
				slot = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((BigArrays.get(key, pos))))) & mask;
				if (last <= pos ? last >= slot || slot > pos : last >= slot && slot > pos)
					break;
				pos = (pos + 1) & mask;
			}
			set(key, last, BigArrays.get(key, pos));
		}
	}
	private boolean removeEntry(final int base, final int displ) {
		size--;
		shiftKeys(base * (long) BigArrays.SEGMENT_SIZE + displ);
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return true;
	}
	private boolean removeNullEntry() {
		containsNull = false;
		size--;
		if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE)
			rehash(n / 2);
		return true;
	}
	@Override
	public boolean remove(final int k) {
		if (((k) == (0))) {
			if (containsNull)
				return removeNullEntry();
			return false;
		}
		int curr;
		final int[][] key = this.key;
		final long h = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((k))));
		int displ, base;
		// The starting point.
		if (((curr = key[base = (int) ((h & mask) >>> BigArrays.SEGMENT_SHIFT)][displ = (int) (h
				& segmentMask)]) == (0)))
			return false;
		if (((curr) == (k)))
			return removeEntry(base, displ);
		while (true) {
			if (((curr = key[base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0))
					& baseMask][displ]) == (0)))
				return false;
			if (((curr) == (k)))
				return removeEntry(base, displ);
		}
	}
	@Override
	public boolean contains(final int k) {
		if (((k) == (0)))
			return containsNull;
		int curr;
		final int[][] key = this.key;
		final long h = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((k))));
		int displ, base;
		// The starting point.
		if (((curr = key[base = (int) ((h & mask) >>> BigArrays.SEGMENT_SHIFT)][displ = (int) (h
				& segmentMask)]) == (0)))
			return false;
		if (((curr) == (k)))
			return true;
		while (true) {
			if (((curr = key[base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0))
					& baseMask][displ]) == (0)))
				return false;
			if (((curr) == (k)))
				return true;
		}
	}
	/*
	 * Removes all elements from this set.
	 *
	 */
	
{@inheritDoc}
 To increase object reuse, this method does not change the table size. If you want to reduce the table size, you must use trim(long). /**
	 * {@inheritDoc}
	 *
	 * <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(long)}.
	 */
	@Override
	public void clear() {
		if (size == 0)
			return;
		size = 0;
		containsNull = false;
		fill(key, (0));
	}
	
An iterator over a hash big set. /** An iterator over a hash big set. */
	private class SetIterator implements IntIterator {
		
The base of the last entry returned, if positive or zero; initially, the number of components of the key array. If negative, the last element returned was that of index - base - 1 from the wrapped list. /**
		 * The base of the last entry returned, if positive or zero; initially, the
		 * number of components of the key array. If negative, the last element returned
		 * was that of index {@code - base - 1} from the {@link #wrapped} list.
		 */
		int base = key.length;
		
The displacement of the last entry returned; initially, zero. /** The displacement of the last entry returned; initially, zero. */
		int displ;
		
The index of the last entry that has been returned (or Long.MIN_VALUE if base is negative). It is -1 if either we did not return an entry yet, or the last returned entry has been removed. /**
		 * The index of the last entry that has been returned (or {@link Long#MIN_VALUE}
		 * if {@link #base} is negative). It is -1 if either we did not return an entry
		 * yet, or the last returned entry has been removed.
		 */
		long last = -1;
		
A downward counter measuring how many entries must still be returned. /** A downward counter measuring how many entries must still be returned. */
		long c = size;
		
A boolean telling us whether we should return the null key. /** A boolean telling us whether we should return the null key. */
		boolean mustReturnNull = IntOpenHashBigSet.this.containsNull;
		
A lazily allocated list containing elements that have wrapped around the
table because of removals.
/**
		 * A lazily allocated list containing elements that have wrapped around the
		 * table because of removals.
		 */
		IntArrayList wrapped;
		@Override
		public boolean hasNext() {
			return c != 0;
		}
		@Override
		public int nextInt() {
			if (!hasNext())
				throw new NoSuchElementException();
			c--;
			if (mustReturnNull) {
				mustReturnNull = false;
				last = n;
				return (0);
			}
			final int[][] key = IntOpenHashBigSet.this.key;
			for (;;) {
				if (displ == 0 && base <= 0) {
					// We are just enumerating elements from the wrapped list.
					last = Long.MIN_VALUE;
					return wrapped.getInt(-(--base) - 1);
				}
				if (displ-- == 0)
					displ = key[--base].length - 1;
				final int k = key[base][displ];
				if (!((k) == (0))) {
					last = base * (long) BigArrays.SEGMENT_SIZE + displ;
					return k;
				}
			}
		}
		
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.
		 */
		private final void shiftKeys(long pos) {
			// Shift entries with the same hash.
			long last, slot;
			int curr;
			final int[][] key = IntOpenHashBigSet.this.key;
			for (;;) {
				pos = ((last = pos) + 1) & mask;
				for (;;) {
					if (((curr = BigArrays.get(key, pos)) == (0))) {
						set(key, last, (0));
						return;
					}
					slot = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((curr)))) & mask;
					if (last <= pos ? last >= slot || slot > pos : last >= slot && slot > pos)
						break;
					pos = (pos + 1) & mask;
				}
				if (pos < last) { // Wrapped entry.
					if (wrapped == null)
						wrapped = new IntArrayList();
					wrapped.add(BigArrays.get(key, pos));
				}
				set(key, last, curr);
			}
		}
		@Override
		public void remove() {
			if (last == -1)
				throw new IllegalStateException();
			if (last == n)
				IntOpenHashBigSet.this.containsNull = false;
			else if (base >= 0)
				shiftKeys(last);
			else {
				// We're removing wrapped entries.
				IntOpenHashBigSet.this.remove(wrapped.getInt(-base - 1));
				last = -1; // Note that we must not decrement size
				return;
			}
			size--;
			last = -1; // You can no longer remove this entry.
			if (ASSERTS)
				checkTable();
		}
	}
	@Override
	public IntIterator iterator() {
		return new SetIterator();
	}
	
Rehashes this set, 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(long)
Returns:
true if there was enough memory to trim the set./**
	 * Rehashes this set, 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 set.
	 * @see #trim(long)
	 */
	public boolean trim() {
		return trim(size);
	}
	
Rehashes this set if the table is too large.

Let N be the smallest table size that can hold
max(n,size64()) 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 set in a table of size
N.
 This method is useful when reusing sets. Clearing a set leaves the table size untouched. If you are reusing a set 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 sets. 
Params:
n – 
           the threshold for the trimming.
See Also:
trim()
Returns:
true if there was enough memory to trim the set./**
	 * Rehashes this set if the table is too large.
	 *
	 * <p>
	 * Let <var>N</var> be the smallest table size that can hold
	 * <code>max(n,{@link #size64()})</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 set in a table of size
	 * <var>N</var>.
	 *
	 * <p>
	 * This method is useful when reusing sets. {@linkplain #clear() Clearing a set}
	 * leaves the table size untouched. If you are reusing a set 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 sets.
	 *
	 * @param n
	 *            the threshold for the trimming.
	 * @return true if there was enough memory to trim the set.
	 * @see #trim()
	 */
	public boolean trim(final long n) {
		final long l = bigArraySize(n, f);
		if (l >= this.n || size > maxFill(l, f))
			return true;
		try {
			rehash(l);
		} catch (OutOfMemoryError cantDoIt) {
			return false;
		}
		return true;
	}
	
Resizes the set.

This method implements the basic rehashing strategy, and may be overriden 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/**
	 * Resizes the set.
	 *
	 * <p>
	 * This method implements the basic rehashing strategy, and may be overriden 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 long newN) {
		final int key[][] = this.key;
		final int newKey[][] = IntBigArrays.newBigArray(newN);
		final long mask = newN - 1; // Note that this is used by the hashing macro
		final int newSegmentMask = newKey[0].length - 1;
		final int newBaseMask = newKey.length - 1;
		int base = 0, displ = 0, b, d;
		long h;
		int k;
		for (long i = realSize(); i-- != 0;) {
			while (((key[base][displ]) == (0)))
				base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0));
			k = key[base][displ];
			h = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((k))));
			// The starting point.
			if (!((newKey[b = (int) ((h & mask) >>> BigArrays.SEGMENT_SHIFT)][d = (int) (h & newSegmentMask)]) == (0)))
				while (!((newKey[b = (b + ((d = (d + 1) & newSegmentMask) == 0 ? 1 : 0)) & newBaseMask][d]) == (0)));
			newKey[b][d] = k;
			base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0));
		}
		this.n = newN;
		this.key = newKey;
		initMasks();
		maxFill = maxFill(n, f);
	}
	@Deprecated
	@Override
	public int size() {
		return (int) Math.min(Integer.MAX_VALUE, size);
	}
	@Override
	public long size64() {
		return size;
	}
	@Override
	public boolean isEmpty() {
		return size == 0;
	}
	
Returns a deep copy of this big set.

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

	public IntOpenHashBigSet clone() {
		IntOpenHashBigSet c;
		try {
			c = (IntOpenHashBigSet) super.clone();
		} catch (CloneNotSupportedException cantHappen) {
			throw new InternalError();
		}
		c.key = copy(key);
		c.containsNull = containsNull;
		return c;
	}
	
Returns a hash code for this set. 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 set./**
	 * Returns a hash code for this set.
	 *
	 * 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 set.
	 */
	@Override
	public int hashCode() {
		final int key[][] = this.key;
		int h = 0, base = 0, displ = 0;
		for (long j = realSize(); j-- != 0;) {
			while (((key[base][displ]) == (0)))
				base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0));
			h += (key[base][displ]);
			base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0));
		}
		return h;
	}
	private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException {
		final IntIterator i = iterator();
		s.defaultWriteObject();
		for (long j = size; j-- != 0;)
			s.writeInt(i.nextInt());
	}

	private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, ClassNotFoundException {
		s.defaultReadObject();
		n = bigArraySize(size, f);
		maxFill = maxFill(n, f);
		final int[][] key = this.key = IntBigArrays.newBigArray(n);
		initMasks();
		long h;
		int k;
		int base, displ;
		for (long i = size; i-- != 0;) {
			k = s.readInt();
			if (((k) == (0)))
				containsNull = true;
			else {
				h = (it.unimi.dsi.fastutil.HashCommon.mix((long) ((k))));
				if (!((key[base = (int) ((h & mask) >>> BigArrays.SEGMENT_SHIFT)][displ = (int) (h
						& segmentMask)]) == (0)))
					while (!((key[base = (base + ((displ = (displ + 1) & segmentMask) == 0 ? 1 : 0))
							& baseMask][displ]) == (0)));
				key[base][displ] = k;
			}
		}
		if (ASSERTS)
			checkTable();
	}
	private void checkTable() {
	}
}