/*

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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 */

package jdk.nashorn.internal.runtime.arrays;

import java.util.Iterator;

import java.util.List;

import jdk.nashorn.api.scripting.JSObject;

import jdk.nashorn.internal.runtime.JSType;

import jdk.nashorn.internal.runtime.ScriptObject;

/**

 * Superclass for array iterators

 * TODO: rewrite these

 *

 * @param <T> element type

 */

abstract public class ArrayLikeIterator<T> implements Iterator<T> {

    /** current element index in iteration */

    protected long index;

    /** should undefined elements be included in the iteration? */

    protected final boolean includeUndefined;

    /**

     * Constructor

     *

     * @param includeUndefined should undefined elements be included in the iteration?

     */

    ArrayLikeIterator(final boolean includeUndefined) {

        this.includeUndefined = includeUndefined;

        this.index = 0;

    }

    /**

     * Is this a reverse order iteration?

     * @return true if reverse

     */

    public boolean isReverse() {

        return false;

    }

    /**

     * Go the the next valid element index of the iterator

     * @return next index

     */

    protected long bumpIndex() {

        return index++;

    }

    /**

     * Return the next valid element index of the iterator

     * @return next index

     */

    public long nextIndex() {

        return index;

    }

    @Override

    public void remove() {

        throw new UnsupportedOperationException("remove");

    }

    /**

     * Get the length of the iteration

     * @return length

     */

    public abstract long getLength();

    /**

     * ArrayLikeIterator factory

     *

     * @param object object over which to do element iteration

     * @return iterator

     */

    public static ArrayLikeIterator<Object> arrayLikeIterator(final Object object) {

        return arrayLikeIterator(object, false);

    }

    /**

     * ArrayLikeIterator factory (reverse order)

     * @param object object over which to do reverse element iteration

     * @return iterator

     */

    public static ArrayLikeIterator<Object> reverseArrayLikeIterator(final Object object) {

        return reverseArrayLikeIterator(object, false);

    }

    /**

     * ArrayLikeIterator factory

     * @param object object over which to do reverse element iteration

     * @param includeUndefined should undefined elements be included in the iteration

     * @return iterator

     */

    public static ArrayLikeIterator<Object> arrayLikeIterator(final Object object, final boolean includeUndefined) {

        Object obj = object;

        if (ScriptObject.isArray(obj)) {

            return new ScriptArrayIterator((ScriptObject) obj, includeUndefined);

        }

        obj = JSType.toScriptObject(obj);

        if (obj instanceof ScriptObject) {

            return new ScriptObjectIterator((ScriptObject)obj, includeUndefined);

        }

        if (obj instanceof JSObject) {

            return new JSObjectIterator((JSObject)obj, includeUndefined);

        }

        if (obj instanceof List) {

            return new JavaListIterator((List<?>)obj, includeUndefined);

        }

        if (obj != null && obj.getClass().isArray()) {

            return new JavaArrayIterator(obj, includeUndefined);

        }

        return new EmptyArrayLikeIterator();

    }

    /**

     * ArrayLikeIterator factory (reverse order)

     * @param object object over which to do reverse element iteration

     * @param includeUndefined should undefined elements be included in the iteration

     * @return iterator

     */

    public static ArrayLikeIterator<Object> reverseArrayLikeIterator(final Object object, final boolean includeUndefined) {

        Object obj = object;

        if (ScriptObject.isArray(obj)) {

            return new ReverseScriptArrayIterator((ScriptObject) obj, includeUndefined);

        }

        obj = JSType.toScriptObject(obj);

        if (obj instanceof ScriptObject) {

            return new ReverseScriptObjectIterator((ScriptObject)obj, includeUndefined);

        }

        if (obj instanceof JSObject) {

            return new ReverseJSObjectIterator((JSObject)obj, includeUndefined);

        }

        if (obj instanceof List) {

            return new ReverseJavaListIterator((List<?>)obj, includeUndefined);

        }

        if (obj != null && obj.getClass().isArray()) {

            return new ReverseJavaArrayIterator(obj, includeUndefined);

        }

        return new EmptyArrayLikeIterator();

    }

}