SquirrelJME/SquirrelJME

// -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
// ---------------------------------------------------------------------------
// SquirrelJME
//     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
// ---------------------------------------------------------------------------
// SquirrelJME is under the Mozilla Public License Version 2.0.
// See license.mkd for licensing and copyright information.
// ---------------------------------------------------------------------------

package net.multiphasicapps.collections;

import java.util.AbstractList;
import java.util.List;
import java.util.RandomAccess;
import org.jetbrains.annotations.UnmodifiableView;

/**
 * This is a list representation of an array which cannot be modified.
 *
 * @param <T> The type of values to store.
 * @since 2018/05/13
 */
@UnmodifiableView
public final class UnmodifiableArrayList<T>
    extends AbstractList<T>
    implements RandomAccess
{
    /** The element offset. */
    protected final int offset;
    
    /** The element length. */
    protected final int length;
    
    /** The source elements. */
    private final T[] _source;
    
    /**
     * Initializes the list.
     *
     * @param __a The input array.
     * @param __o The offset into the array.
     * @param __l The number of elements to read.
     * @throws ArrayIndexOutOfBoundsException If the offset and/or length are
     * negative or exceed the array bounds.
     * @throws NullPointerException On null arguments.
     * @since 2018/05/13
     */
    UnmodifiableArrayList(T[] __a, int __o, int __l)
        throws ArrayIndexOutOfBoundsException, NullPointerException
    {
        if (__a == null)
            throw new NullPointerException("NARG");
        if (__o < 0 || __l < 0 || (__o + __l) < 0 || (__o + __l) > __a.length)
            throw new ArrayIndexOutOfBoundsException("IOOB");
        
        this._source = __a;
        this.offset = __o;
        this.length = __l;
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/05/13
     */
    @Override
    public final T get(int __i)
        throws IndexOutOfBoundsException
    {
        if (__i < 0 || __i >= this.length)
            throw new IndexOutOfBoundsException(String.format("IOOB %d", __i));
        
        return this._source[this.offset + __i];
    }
    
    /**
     * {@inheritDoc}
     * @since 2018/05/13
     */
    @Override
    public final int size()
    {
        return this.length;
    }
    
    /**
     * Wraps the given array.
     *
     * @param <T> The list type.
     * @param __a The array to wrap.
     * @return The iterator for the array.
     * @throws NullPointerException On null arguments.
     * @since 2018/05/13
     */
    @SuppressWarnings({"unchecked"})
    public static <T> List<T> of(T... __a)
        throws NullPointerException
    {
        if (__a == null)
            throw new NullPointerException("NARG");
        
        return new UnmodifiableArrayList<T>(__a, 0, __a.length);
    }
    
    /**
     * Wraps the given array.
     *
     * @param <T> The list type.
     * @param __a The input array.
     * @param __o The offset into the array.
     * @param __l The number of elements to read.
     * @throws ArrayIndexOutOfBoundsException If the offset and/or length are
     * negative or exceed the array bounds.
     * @return The iterator for the array.
     * @throws NullPointerException On null arguments.
     * @since 2018/05/13
     */
    public static <T> List<T> of(T[] __a, int __o, int __l)
        throws ArrayIndexOutOfBoundsException, NullPointerException
    {
        if (__a == null)
            throw new NullPointerException("NARG");
        if (__o < 0 || __l < 0 || (__o + __l) < 0 || (__o + __l) > __a.length)
            throw new ArrayIndexOutOfBoundsException("IOOB");
        
        return new UnmodifiableArrayList<T>(__a, __o, __l);
    }
}