IntList.java

/*
 * Copyright (C) 2008, Google Inc.
 * Copyright (C) 2009, Johannes Schindelin <johannes.schindelin@gmx.de> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.eclipse.jgit.util;

/**
 * A more efficient List&lt;Integer&gt; using a primitive integer array.
 */
public class IntList {
    private int[] entries;

    private int count;

    /**
     * Create an empty list with a default capacity.
     */
    public IntList() {
        this(10);
    }

    /**
     * Create an empty list with the specified capacity.
     *
     * @param capacity
     *            number of entries the list can initially hold.
     */
    public IntList(int capacity) {
        entries = new int[capacity];
    }

    /**
     * Get number of entries in this list.
     *
     * @return number of entries in this list.
     */
    public int size() {
        return count;
    }

    /**
     * Check if an entry appears in this collection.
     *
     * @param value
     *            the value to search for.
     * @return true of {@code value} appears in this list.
     * @since 4.9
     */
    public boolean contains(int value) {
        for (int i = 0; i < count; i++)
            if (entries[i] == value)
                return true;
        return false;
    }

    /**
     * Get the value at the specified index
     *
     * @param i
     *            index to read, must be in the range [0, {@link #size()}).
     * @return the number at the specified index
     * @throws java.lang.ArrayIndexOutOfBoundsException
     *             the index outside the valid range
     */
    public int get(int i) {
        if (count <= i)
            throw new ArrayIndexOutOfBoundsException(i);
        return entries[i];
    }

    /**
     * Empty this list
     */
    public void clear() {
        count = 0;
    }

    /**
     * Add an entry to the end of the list.
     *
     * @param n
     *            the number to add.
     */
    public void add(int n) {
        if (count == entries.length)
            grow();
        entries[count++] = n;
    }

    /**
     * Assign an entry in the list.
     *
     * @param index
     *            index to set, must be in the range [0, {@link #size()}).
     * @param n
     *            value to store at the position.
     */
    public void set(int index, int n) {
        if (count < index)
            throw new ArrayIndexOutOfBoundsException(index);
        else if (count == index)
            add(n);
        else
            entries[index] = n;
    }

    /**
     * Pad the list with entries.
     *
     * @param toIndex
     *            index position to stop filling at. 0 inserts no filler. 1
     *            ensures the list has a size of 1, adding <code>val</code> if
     *            the list is currently empty.
     * @param val
     *            value to insert into padded positions.
     */
    public void fillTo(int toIndex, int val) {
        while (count < toIndex)
            add(val);
    }

    private void grow() {
        final int[] n = new int[(entries.length + 16) * 3 / 2];
        System.arraycopy(entries, 0, n, 0, count);
        entries = n;
    }

    /** {@inheritDoc} */
    @Override
    public String toString() {
        final StringBuilder r = new StringBuilder();
        r.append('[');
        for (int i = 0; i < count; i++) {
            if (i > 0)
                r.append(", "); //$NON-NLS-1$
            r.append(entries[i]);
        }
        r.append(']');
        return r.toString();
    }
}