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 cc.squirreljme.runtime.cldc.util;

import java.util.Iterator;
import java.util.NoSuchElementException;
import org.jetbrains.annotations.UnmodifiableView;

/**
 * This is an iterator where elements cannot be removed and where it iterates
 * over an array.
 *
 * @param <T> The type to use.
 * @since 2018/05/13
 */
@UnmodifiableView
public final class UnmodifiableArrayIterator<T>
    implements Iterator<T>
{
    /** The element limit. */
    protected final int limit;
    
    /** The source elements, cleared when empty. */
    private T[] _source;
    
    /** The current element. */
    private int _at;
    
    /**
     * Initializes the iterator.
     *
     * @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
     */
    UnmodifiableArrayIterator(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.limit = __o + __l;
        this._source = __a;
        this._at = __o;
    }
    
    /**
     * {@inheritDoc}
     * @since 2108/05/13
     */
    @Override
    public final boolean hasNext()
    {    
        return (this._at < this.limit);
    }
    
    /**
     * {@inheritDoc}
     * @since 2108/05/13
     */
    @Override
    public final T next()
        throws NoSuchElementException
    {
        // Is at the end?
        int at = this._at;
        if (at >= this.limit)
        {
            this._source = null;
            throw new NoSuchElementException("NSEE");
        }
        
        this._at = at + 1;
        return this._source[at];
    }
    
    /**
     * {@inheritDoc}
     * @throws UnsupportedOperationException Always.
     * @since 2108/05/13
     */
    @Override
    public final void remove()
        throws UnsupportedOperationException
    {
        throw new UnsupportedOperationException("RORO");
    }
    
    /**
     * Wraps the given array.
     *
     * @param <T> The iterator 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> Iterator<T> of(T... __a)
        throws NullPointerException
    {
        if (__a == null)
            throw new NullPointerException("NARG");
        
        return new UnmodifiableArrayIterator<T>(__a, 0, __a.length);
    }
    
    /**
     * Wraps the given array.
     *
     * @param <T> The iterator 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> Iterator<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 UnmodifiableArrayIterator<T>(__a, __o, __l);
    }
}