/*
 * Copyright (c) 2018 Goldman Sachs.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompany this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */

package org.eclipse.collections.impl.bag.mutable;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Arrays;

import org.eclipse.collections.api.bag.Bag;
import org.eclipse.collections.api.bag.MutableBag;
import org.eclipse.collections.api.block.predicate.primitive.IntPredicate;
import org.eclipse.collections.api.map.primitive.MutableObjectIntMap;
import org.eclipse.collections.impl.map.mutable.primitive.ObjectIntHashMap;
import org.eclipse.collections.impl.utility.ArrayIterate;
import org.eclipse.collections.impl.utility.Iterate;

A HashBag is a MutableBag which uses a Map as its underlying data store. Each key in the Map represents some item, and the value in the map represents the current number of occurrences of that item.
Since:1.0
/** * A HashBag is a MutableBag which uses a Map as its underlying data store. Each key in the Map represents some item, * and the value in the map represents the current number of occurrences of that item. * * @since 1.0 */
public class HashBag<T> extends AbstractHashBag<T> implements Externalizable { private static final long serialVersionUID = 1L; public HashBag() { this.items = ObjectIntHashMap.newMap(); } public HashBag(int size) { this.items = new ObjectIntHashMap<>(size); } private HashBag(MutableObjectIntMap<T> map) { this.items = map; this.size = (int) map.sum(); } public static <E> HashBag<E> newBag() { return new HashBag<>(); } public static <E> HashBag<E> newBag(int size) { return new HashBag<>(size); } public static <E> HashBag<E> newBag(Bag<? extends E> source) { HashBag<E> result = HashBag.newBag(source.sizeDistinct()); result.addAllBag(source); return result; } public static <E> HashBag<E> newBag(Iterable<? extends E> source) { if (source instanceof Bag) { return HashBag.newBag((Bag<E>) source); } return HashBag.newBagWith((E[]) Iterate.toArray(source)); } public static <E> HashBag<E> newBagWith(E... elements) { HashBag<E> result = HashBag.newBag(); ArrayIterate.addAllTo(elements, result); return result; } @Override protected int computeHashCode(T item) { return item.hashCode(); } @Override public MutableBag<T> selectByOccurrences(IntPredicate predicate) { MutableObjectIntMap<T> map = this.items.select((each, occurrences) -> { return predicate.accept(occurrences); }); return new HashBag<>(map); } @Override public void writeExternal(ObjectOutput out) throws IOException { ((ObjectIntHashMap<T>) this.items).writeExternal(out); } @Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException { this.items = new ObjectIntHashMap<>(); ((ObjectIntHashMap<T>) this.items).readExternal(in); this.size = (int) this.items.sum(); } @Override public HashBag<T> without(T element) { this.remove(element); return this; } @Override public MutableBag<T> newEmpty() { return HashBag.newBag(); } @Override public HashBag<T> with(T element) { this.add(element); return this; } @Override public HashBag<T> withAll(Iterable<? extends T> iterable) { this.addAllIterable(iterable); return this; } @Override public HashBag<T> withoutAll(Iterable<? extends T> iterable) { this.removeAllIterable(iterable); return this; } public HashBag<T> with(T... elements) { this.addAll(Arrays.asList(elements)); return this; } public HashBag<T> with(T element1, T element2) { this.add(element1); this.add(element2); return this; } public HashBag<T> with(T element1, T element2, T element3) { this.add(element1); this.add(element2); this.add(element3); return this; } }