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fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists, and queues with a small memory footprint and fast operations; it provides also big (64-bit) arrays, sets, and lists, sorting algorithms, fast, practical I/O classes for binary and text files, and facilities for memory mapping large files. This jar (fastutil-core.jar) contains data structures based on integers, longs, doubles, and objects, only; fastutil.jar contains all classes. If you have both jars in your dependencies, this jar should be excluded.

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/*
	* Copyright (C) 2002-2022 Sebastiano Vigna
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	*     http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
package it.unimi.dsi.fastutil.longs;

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.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * A type-specific hash set with a fast, small-footprint implementation whose
 * {@linkplain it.unimi.dsi.fastutil.Hash.Strategy hashing strategy} is specified at creation time.
 *
 * 

* Instances of this class use a hash table to represent a set. 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 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 {@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. * * @see Hash * @see HashCommon */ public class LongOpenCustomHashSet extends AbstractLongSet implements java.io.Serializable, Cloneable, Hash { private static final long serialVersionUID = 0L; private static final boolean ASSERTS = false; /** The array of keys. */ protected transient long[] key; /** The mask for wrapping a position counter. */ protected transient int mask; /** Whether this set contains the null key. */ protected transient boolean containsNull; /** The hash strategy of this custom set. */ protected it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy; /** * The current table size. Note that an additional element is allocated for storing the null key. */ protected transient int n; /** 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}. */ protected final transient int minN; /** Number of entries in the set (including the null key, if present). */ protected int size; /** The acceptable load factor. */ protected final float f; /** * Creates a new hash set. * *

* 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 set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final int expected, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this.strategy = strategy; if (f <= 0 || f >= 1) throw new IllegalArgumentException("Load factor must be greater than 0 and smaller than 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 long[n + 1]; } /** * Creates a new hash set with {@link Hash#DEFAULT_LOAD_FACTOR} as load factor. * * @param expected the expected number of elements in the hash set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final int expected, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(expected, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set with initial expected {@link Hash#DEFAULT_INITIAL_SIZE} elements and * {@link Hash#DEFAULT_LOAD_FACTOR} as load factor. * * @param strategy the strategy. */ public LongOpenCustomHashSet(final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set copying a given collection. * * @param c a {@link Collection} to be copied into the new hash set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final Collection c, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(c.size(), f, strategy); addAll(c); } /** * Creates a new hash 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 set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final Collection c, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(c, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set copying a given type-specific collection. * * @param c a type-specific collection to be copied into the new hash set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final LongCollection c, final float f, it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(c.size(), f, strategy); addAll(c); } /** * Creates a new hash 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 set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final LongCollection c, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(c, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set using elements provided by a type-specific iterator. * * @param i a type-specific iterator whose elements will fill the set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final LongIterator i, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(DEFAULT_INITIAL_SIZE, f, strategy); while (i.hasNext()) add(i.nextLong()); } /** * Creates a new hash 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 set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final LongIterator i, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(i, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set using elements provided by an iterator. * * @param i an iterator whose elements will fill the set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final Iterator i, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(LongIterators.asLongIterator(i), f, strategy); } /** * Creates a new hash 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 set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final Iterator i, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(LongIterators.asLongIterator(i), strategy); } /** * Creates a new hash set and fills it with the elements of a given array. * * @param a an array whose elements will be used to fill the set. * @param offset the first element to use. * @param length the number of elements to use. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final long[] a, final int offset, final int length, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(length < 0 ? 0 : length, f, strategy); LongArrays.ensureOffsetLength(a, offset, length); for (int i = 0; i < length; i++) add(a[offset + i]); } /** * Creates a new hash 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 set. * @param offset the first element to use. * @param length the number of elements to use. * @param strategy the strategy. */ public LongOpenCustomHashSet(final long[] a, final int offset, final int length, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(a, offset, length, DEFAULT_LOAD_FACTOR, strategy); } /** * Creates a new hash set copying the elements of an array. * * @param a an array to be copied into the new hash set. * @param f the load factor. * @param strategy the strategy. */ public LongOpenCustomHashSet(final long[] a, final float f, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(a, 0, a.length, f, strategy); } /** * Creates a new hash 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 set. * @param strategy the strategy. */ public LongOpenCustomHashSet(final long[] a, final it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy) { this(a, DEFAULT_LOAD_FACTOR, strategy); } /** * Returns the hashing strategy. * * @return the hashing strategy of this custom hash set. */ public it.unimi.dsi.fastutil.longs.LongHash.Strategy strategy() { return strategy; } private int realSize() { return containsNull ? 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); } @Override public boolean addAll(LongCollection c) { if (f <= .5) ensureCapacity(c.size()); // The resulting collection will be sized for c.size() elements else tryCapacity(size() + c.size()); // The resulting collection will be tentatively sized for size() + c.size() // elements return super.addAll(c); } @Override public boolean addAll(Collection c) { // The resulting collection will be at least c.size() big if (f <= .5) ensureCapacity(c.size()); // The resulting collection will be sized for c.size() elements else tryCapacity(size() + c.size()); // The resulting collection will be tentatively sized for size() + c.size() // elements return super.addAll(c); } @Override public boolean add(final long k) { int pos; if ((strategy.equals((k), (0)))) { if (containsNull) return false; containsNull = true; key[n] = k; } else { long curr; final long[] key = this.key; // The starting point. if (!((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(k))) & mask]) == (0))) { if ((strategy.equals((curr), (k)))) return false; while (!((curr = key[pos = (pos + 1) & mask]) == (0))) if ((strategy.equals((curr), (k)))) return false; } key[pos] = k; } if (size++ >= maxFill) rehash(arraySize(size + 1, f)); if (ASSERTS) checkTable(); return true; } /** * 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; long curr; final long[] key = this.key; for (;;) { pos = ((last = pos) + 1) & mask; for (;;) { if (((curr = key[pos]) == (0))) { key[last] = (0); return; } slot = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(curr))) & mask; if (last <= pos ? last >= slot || slot > pos : last >= slot && slot > pos) break; pos = (pos + 1) & mask; } key[last] = curr; } } private boolean removeEntry(final int pos) { size--; shiftKeys(pos); if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE) rehash(n / 2); return true; } private boolean removeNullEntry() { containsNull = false; key[n] = (0); size--; if (n > minN && size < maxFill / 4 && n > DEFAULT_INITIAL_SIZE) rehash(n / 2); return true; } @Override public boolean remove(final long k) { if ((strategy.equals((k), (0)))) { if (containsNull) return removeNullEntry(); return false; } long curr; final long[] key = this.key; int pos; // The starting point. if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(k))) & mask]) == (0))) return false; if ((strategy.equals((k), (curr)))) return removeEntry(pos); while (true) { if (((curr = key[pos = (pos + 1) & mask]) == (0))) return false; if ((strategy.equals((k), (curr)))) return removeEntry(pos); } } @Override public boolean contains(final long k) { if ((strategy.equals((k), (0)))) return containsNull; long curr; final long[] key = this.key; int pos; // The starting point. if (((curr = key[pos = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(k))) & mask]) == (0))) return false; if ((strategy.equals((k), (curr)))) return true; while (true) { if (((curr = key[pos = (pos + 1) & mask]) == (0))) return false; if ((strategy.equals((k), (curr)))) return true; } } /* Removes all elements from this set. * *

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; containsNull = false; Arrays.fill(key, (0)); } @Override public int size() { return size; } @Override public boolean isEmpty() { return size == 0; } /** An iterator over a hash set. */ private final class SetIterator implements LongIterator { /** * The index of the last entry returned, if positive or zero; initially, {@link #n}. If negative, * the last element returned was that of index {@code - pos - 1} from the {@link #wrapped} list. */ int pos = n; /** * The index of the last entry that has been returned (more precisely, the value of {@link #pos} if * {@link #pos} is positive, or {@link Integer#MIN_VALUE} if {@link #pos} is negative). It is -1 if * either we did not return an entry yet, or the last returned entry has been removed. */ int last = -1; /** A downward counter measuring how many entries must still be returned. */ int c = size; /** A boolean telling us whether we should return the null key. */ boolean mustReturnNull = LongOpenCustomHashSet.this.containsNull; /** * A lazily allocated list containing elements that have wrapped around the table because of * removals. */ LongArrayList wrapped; @Override public boolean hasNext() { return c != 0; } @Override public long nextLong() { if (!hasNext()) throw new NoSuchElementException(); c--; if (mustReturnNull) { mustReturnNull = false; last = n; return key[n]; } final long key[] = LongOpenCustomHashSet.this.key; for (;;) { if (--pos < 0) { // We are just enumerating elements from the wrapped list. last = Integer.MIN_VALUE; return wrapped.getLong(-pos - 1); } if (!((key[pos]) == (0))) return key[last = pos]; } } /** * 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(int pos) { // Shift entries with the same hash. int last, slot; long curr; final long[] key = LongOpenCustomHashSet.this.key; for (;;) { pos = ((last = pos) + 1) & mask; for (;;) { if (((curr = key[pos]) == (0))) { key[last] = (0); return; } slot = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(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 LongArrayList(2); wrapped.add(key[pos]); } key[last] = curr; } } @Override public void remove() { if (last == -1) throw new IllegalStateException(); if (last == n) { LongOpenCustomHashSet.this.containsNull = false; LongOpenCustomHashSet.this.key[n] = (0); } else if (pos >= 0) shiftKeys(last); else { // We're removing wrapped entries. LongOpenCustomHashSet.this.remove(wrapped.getLong(-pos - 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 void forEachRemaining(final java.util.function.LongConsumer action) { final long key[] = LongOpenCustomHashSet.this.key; if (mustReturnNull) { mustReturnNull = false; last = n; action.accept(key[n]); c--; } while (c != 0) { if (--pos < 0) { // We are just enumerating elements from the wrapped list. last = Integer.MIN_VALUE; action.accept(wrapped.getLong(-pos - 1)); c--; } else if (!((key[pos]) == (0))) { action.accept(key[last = pos]); c--; } } } } @Override public LongIterator iterator() { return new SetIterator(); } private final class SetSpliterator implements LongSpliterator { private static final int POST_SPLIT_CHARACTERISTICS = LongSpliterators.SET_SPLITERATOR_CHARACTERISTICS & ~java.util.Spliterator.SIZED; /** * The index (which bucket) of the next item to give to the action. Unlike {@link SetIterator}, this * counts up instead of down. */ int pos = 0; /** The maximum bucket (exclusive) to iterate to */ int max = n; /** An upwards counter counting how many we have given */ int c = 0; /** A boolean telling us whether we should return the null key. */ boolean mustReturnNull = LongOpenCustomHashSet.this.containsNull; boolean hasSplit = false; SetSpliterator() { } SetSpliterator(int pos, int max, boolean mustReturnNull, boolean hasSplit) { this.pos = pos; this.max = max; this.mustReturnNull = mustReturnNull; this.hasSplit = hasSplit; } @Override public boolean tryAdvance(final java.util.function.LongConsumer action) { if (mustReturnNull) { mustReturnNull = false; ++c; action.accept(key[n]); return true; } final long key[] = LongOpenCustomHashSet.this.key; while (pos < max) { if (!((key[pos]) == (0))) { ++c; action.accept(key[pos++]); return true; } else { ++pos; } } return false; } @Override public void forEachRemaining(final java.util.function.LongConsumer action) { final long key[] = LongOpenCustomHashSet.this.key; if (mustReturnNull) { mustReturnNull = false; action.accept(key[n]); ++c; } while (pos < max) { if (!((key[pos]) == (0))) { action.accept(key[pos]); ++c; } ++pos; } } @Override public int characteristics() { return hasSplit ? POST_SPLIT_CHARACTERISTICS : LongSpliterators.SET_SPLITERATOR_CHARACTERISTICS; } @Override public long estimateSize() { if (!hasSplit) { // Root spliterator; we know how many are remaining. return size - c; } else { // After we split, we can no longer know exactly how many we have (or at least not efficiently). // (size / n) * (max - pos) aka currentTableDensity * numberOfBucketsLeft seems like a good // estimate. return Math.min(size - c, (long)(((double)realSize() / n) * (max - pos)) + (mustReturnNull ? 1 : 0)); } } @Override public SetSpliterator trySplit() { if (pos >= max - 1) return null; int retLen = (max - pos) >> 1; if (retLen <= 1) return null; int myNewPos = pos + retLen; int retPos = pos; int retMax = myNewPos; // Since null is returned first, and the convention is that the returned split is the prefix of // elements, // the split will take care of returning null (if needed), and we won't return it anymore. SetSpliterator split = new SetSpliterator(retPos, retMax, mustReturnNull, true); this.pos = myNewPos; this.mustReturnNull = false; this.hasSplit = true; return split; } @Override public long skip(long n) { if (n < 0) throw new IllegalArgumentException("Argument must be nonnegative: " + n); if (n == 0) return 0; long skipped = 0; if (mustReturnNull) { mustReturnNull = false; ++skipped; --n; } final long key[] = LongOpenCustomHashSet.this.key; while (pos < max && n > 0) { if (!((key[pos++]) == (0))) { ++skipped; --n; } } return skipped; } } @Override public LongSpliterator spliterator() { return new SetSpliterator(); } @Override public void forEach(final java.util.function.LongConsumer action) { if (containsNull) action.accept(key[n]); final long key[] = this.key; for (int pos = n; pos-- != 0;) if (!((key[pos]) == (0))) action.accept(key[pos]); } /** * 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. * * @return true if there was enough memory to trim the set. * @see #trim(int) */ 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,{@link #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 set in a table of size * N. * *

* 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 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 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. * * @param newN the new size */ protected void rehash(final int newN) { final long key[] = this.key; final int mask = newN - 1; // Note that this is used by the hashing macro final long newKey[] = new long[newN + 1]; int i = n, pos; for (int j = realSize(); j-- != 0;) { while (((key[--i]) == (0))); if (!((newKey[pos = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(key[i]))) & mask]) == (0))) while (!((newKey[pos = (pos + 1) & mask]) == (0))); newKey[pos] = key[i]; } n = newN; this.mask = mask; maxFill = maxFill(n, f); this.key = newKey; } /** * Returns a deep copy of this set. * *

* This method performs a deep copy of this 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 set. */ @Override public LongOpenCustomHashSet clone() { LongOpenCustomHashSet c; try { c = (LongOpenCustomHashSet)super.clone(); } catch (CloneNotSupportedException cantHappen) { throw new InternalError(); } c.key = key.clone(); c.containsNull = containsNull; c.strategy = strategy; return c; } /** * 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() { int h = 0; for (int j = realSize(), i = 0; j-- != 0;) { while (((key[i]) == (0))) i++; h += (strategy.hashCode(key[i])); i++; } // Zero / null have hash zero. return h; } private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { final LongIterator i = iterator(); s.defaultWriteObject(); for (int j = size; j-- != 0;) s.writeLong(i.nextLong()); } 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 long key[] = this.key = new long[n + 1]; long k; for (int i = size, pos; i-- != 0;) { k = s.readLong(); if ((strategy.equals((k), (0)))) { pos = n; containsNull = true; } else { if (!((key[pos = (it.unimi.dsi.fastutil.HashCommon.mix(strategy.hashCode(k))) & mask]) == (0))) while (!((key[pos = (pos + 1) & mask]) == (0))); } key[pos] = k; } if (ASSERTS) checkTable(); } private void checkTable() { } }





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