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This artifact provides efficient implementations for various collection data structures (esp. linked lists and priority queues), which have very insufficient implementation in the Java Collections Framework that makes it hard or even impossible to exploit their efficiencies.

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/* Copyright (C) 2013-2019 TU Dortmund
 * This file is part of AutomataLib, http://www.automatalib.net/.
 *
 * 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 net.automatalib.commons.smartcollections;

import java.io.Serializable;
import java.util.Arrays;

/**
 * Class that provides a resizable {@code int} array storage.
 *
 * @author Malte Isberner
 */
public final class ResizingIntArray implements CapacityManagement, Serializable {

    /**
     * The arrays default initial capacity.
     */
    public static final int DEFAULT_INITIAL_CAPACITY = 10;

    /**
     * The storage array.
     */
    public int[] array;

    private int nextCapacityHint;

    /**
     * Constructor. Initializes an array of the default initial capacity.
     *
     * @see #DEFAULT_INITIAL_CAPACITY
     */
    public ResizingIntArray() {
        this(DEFAULT_INITIAL_CAPACITY);
    }

    /**
     * Constructor. Creates an array with the specified initial capacity.
     *
     * @param initialCapacity
     *         the initial capacity.
     */
    public ResizingIntArray(int initialCapacity) {
        final int capacity = initialCapacity <= 0 ? DEFAULT_INITIAL_CAPACITY : initialCapacity;
        this.array = new int[capacity];
    }

    @Override
    public boolean ensureCapacity(int minCapacity) {
        if (minCapacity <= array.length) {
            return false;
        }

        final int newCapacity = ArrayUtil.computeNewCapacity(array.length, minCapacity, nextCapacityHint);

        array = Arrays.copyOf(array, newCapacity);
        nextCapacityHint = 0;
        return true;
    }

    @Override
    public boolean ensureAdditionalCapacity(int additionalCapacity) {
        return ensureCapacity(array.length + additionalCapacity);
    }

    @Override
    public void hintNextCapacity(int nextCapacityHint) {
        this.nextCapacityHint = nextCapacityHint;
    }

    /**
     * Shrinks the storage to the specified maximum capacity.
     * 
     * If the current capacity is less or equal to the specified capacity, nothing happens.
     *
     * @param maxCapacity
     *         the maximal number of elements the storage array has to provide room for.
     *
     * @return true iff the storage array had to be resized, false otherwise.
     */
    public boolean shrink(int maxCapacity) {
        if (maxCapacity >= array.length) {
            return false;
        }

        int[] newArray = new int[maxCapacity];
        System.arraycopy(array, 0, newArray, 0, maxCapacity);
        array = newArray;
        return true;
    }

    /**
     * Sets all the elements in the array to the specified value.
     *
     * @param value
     *         the value.
     */
    public void setAll(int value) {
        for (int i = 0; i < array.length; i++) {
            array[i] = value;
        }
    }

    public void swap(ResizingIntArray other) {
        int[] arrayTmp = array;
        int hintTmp = nextCapacityHint;
        array = other.array;
        nextCapacityHint = other.nextCapacityHint;
        other.array = arrayTmp;
        other.nextCapacityHint = hintTmp;
    }

}