/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.xerces.impl.xs.util;

import java.lang.reflect.Array;
import java.util.AbstractList;
import java.util.Iterator;
import java.util.ListIterator;
import java.util.NoSuchElementException;

import org.apache.xerces.xs.XSObject;
import org.apache.xerces.xs.XSObjectList;

Contains a list of XSObjects.
Author:
Sandy Gao, IBM
@xerces.internal
Version:
$Id: XSObjectListImpl.java 776079 2009-05-18 20:22:27Z mrglavas $/**
 * Contains a list of XSObjects.
 *
 * @xerces.internal 
 *
 * @author Sandy Gao, IBM
 *
 * @version $Id: XSObjectListImpl.java 776079 2009-05-18 20:22:27Z mrglavas $
 */
public class XSObjectListImpl extends AbstractList implements XSObjectList {
    
    
An immutable empty list.
/**
     * An immutable empty list.
     */
    public static final XSObjectListImpl EMPTY_LIST = new XSObjectListImpl(new XSObject[0], 0);
    private static final ListIterator EMPTY_ITERATOR = new ListIterator() {
        public boolean hasNext() {
            return false;
        }
        public Object next() {
            throw new NoSuchElementException();
        }
        public boolean hasPrevious() {
            return false;
        }
        public Object previous() {
            throw new NoSuchElementException();
        }
        public int nextIndex() {
            return 0;
        }
        public int previousIndex() {
            return -1;
        }
        public void remove() {
            throw new UnsupportedOperationException();
        }
        public void set(Object object) {
            throw new UnsupportedOperationException();
        }
        public void add(Object object) {
            throw new UnsupportedOperationException();
        }
    };
    
    private static final int DEFAULT_SIZE = 4;

    // The array to hold all data
    private XSObject[] fArray = null;
    // Number of elements in this list
    private int fLength = 0;
    
    public XSObjectListImpl() {
        fArray = new XSObject[DEFAULT_SIZE];
        fLength = 0;
    }

    
Construct an XSObjectList implementation
Params:
array –     the data array
length –    the number of elements/**
     * Construct an XSObjectList implementation
     * 
     * @param array     the data array
     * @param length    the number of elements
     */
    public XSObjectListImpl(XSObject[] array, int length) {
        fArray = array;
        fLength = length;
    }

    
The number of XSObjects in the list. The range of valid
child node indices is 0 to length-1 inclusive.
/**
     * The number of <code>XSObjects</code> in the list. The range of valid
     * child node indices is 0 to <code>length-1</code> inclusive.
     */
    public int getLength() {
        return fLength;
    }

    
Returns the indexth item in the collection. The index
starts at 0. If index is greater than or equal to the
number of nodes in the list, this returns null.
Params:
index – index into the collection.
Returns:
The XSObject at the indexth position in the
  XSObjectList, or null if that is not a
  valid index./**
     * Returns the <code>index</code>th item in the collection. The index
     * starts at 0. If <code>index</code> is greater than or equal to the
     * number of nodes in the list, this returns <code>null</code>.
     * @param index index into the collection.
     * @return The XSObject at the <code>index</code>th position in the
     *   <code>XSObjectList</code>, or <code>null</code> if that is not a
     *   valid index.
     */
    public XSObject item(int index) {
        if (index < 0 || index >= fLength) {
            return null;
        }
        return fArray[index];
    }

    // clear this object
    public void clearXSObjectList() {
        for (int i=0; i<fLength; i++) {
            fArray[i] = null;
        }
        fArray = null;
        fLength = 0;
    }
    
    public void addXSObject(XSObject object) {
       if (fLength == fArray.length) {  
           XSObject[] temp = new XSObject[fLength + 4];
           System.arraycopy(fArray, 0, temp, 0, fLength);
           fArray = temp;
       }
       fArray[fLength++] = object;
    }
    
    public void addXSObject(int index, XSObject object) {
        fArray[index] = object;
    }
    
    /*
     * List methods
     */
    
    public boolean contains(Object value) {
        return (value == null) ? containsNull() : containsObject(value);
    }

    public Object get(int index) {
        if (index >= 0 && index < fLength) {
            return fArray[index];
        }
        throw new IndexOutOfBoundsException("Index: " + index);
    }

    public int size() {
        return getLength();
    }
    
    public Iterator iterator() {
        return listIterator0(0);
    }
    
    public ListIterator listIterator() {
        return listIterator0(0);
    }
    
    public ListIterator listIterator(int index) {
        if (index >= 0 && index < fLength) {
            return listIterator0(index);
        }
        throw new IndexOutOfBoundsException("Index: " + index);
    }
    
    private ListIterator listIterator0(int index) {
        return fLength == 0 ? EMPTY_ITERATOR : new XSObjectListIterator(index);
    }
    
    private boolean containsObject(Object value) {
        for (int i = fLength - 1; i >= 0; --i) {
            if (value.equals(fArray[i])) {
                return true;
            }
        }
        return false;
    }
    
    private boolean containsNull() {
        for (int i = fLength - 1; i >= 0; --i) {
            if (fArray[i] == null) {
                return true;
            }
        }
        return false;
    }
    
    public Object[] toArray() {
        Object[] a = new Object[fLength];
        toArray0(a);
        return a;
    }
    
    public Object[] toArray(Object[] a) {
        if (a.length < fLength) {
            Class arrayClass = a.getClass();
            Class componentType = arrayClass.getComponentType();
            a = (Object[]) Array.newInstance(componentType, fLength);
        }
        toArray0(a);
        if (a.length > fLength) {
            a[fLength] = null;
        }
        return a;
    }
    
    private void toArray0(Object[] a) {
        if (fLength > 0) {
            System.arraycopy(fArray, 0, a, 0, fLength);
        }
    }
    
    private final class XSObjectListIterator implements ListIterator {
        private int index;
        public XSObjectListIterator(int index) {
            this.index = index;
        }
        public boolean hasNext() {
            return (index < fLength);
        }
        public Object next() {
            if (index < fLength) {
                return fArray[index++];
            }
            throw new NoSuchElementException();
        }
        public boolean hasPrevious() {
            return (index > 0);
        }
        public Object previous() {
            if (index > 0) {
                return fArray[--index];
            }
            throw new NoSuchElementException();
        }
        public int nextIndex() {
            return index;
        }
        public int previousIndex() {
            return index - 1;
        }
        public void remove() {
            throw new UnsupportedOperationException();
        }
        public void set(Object o) {
            throw new UnsupportedOperationException();
        }
        public void add(Object o) {
            throw new UnsupportedOperationException();
        }
    }

} // class XSObjectListImpl