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/*
 * 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.commons.beanutils;

import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Map;

/**
 * 
Lazy DynaBean List.

 *
 * 
There are two main purposes for this class:

 *    
    
 *        
  • To provide Lazy List behaviour - automatically
 *            growing and populating the List
 *            with either DynaBean, java.util.Map
 *            or POJO Beans.
    • 
 *        
  • To provide a straight forward way of putting a Collection
 *            or Array into the lazy list and a straight forward
 *            way to get it out again at the end.
    • 
 *    

 *
 * 
All elements added to the List are stored as DynaBean's:

 * 
    
 *    
  • java.util.Map elements are "wrapped" in a LazyDynaMap.
 *    
  • POJO Bean elements are "wrapped" in a WrapDynaBean.
 *    
  • DynaBean's are stored un-changed.
 * 

 *
 * 
toArray()

 * 
The toArray() method returns an array of the
 *    elements of the appropriate type. If the LazyDynaList
 *    is populated with java.util.Map objects a
 *    Map[] array is returned.
 *    If the list is populated with POJO Beans an appropriate
 *    array of the POJO Beans is returned. Otherwise a DynaBean[]
 *    array is returned.
 * 

 *
 * 
toDynaBeanArray()

 * 
The toDynaBeanArray() method returns a
 *    DynaBean[] array of the elements in the List.
 * 

 *
 * 
N.B.All the elements in the List must be the
 *    same type. If the DynaClass or Class
 *    of the LazyDynaList's elements is
 *    not specified, then it will be automatically set to the type
 *    of the first element populated.
 * 

 *
 * 
Example 1

 * 
If you have an array of java.util.Map[] - you can put that into
 *    a LazyDynaList.

 *
 * 

 *    TreeMap[] myArray = .... // your Map[]
 *    List lazyList = new LazyDynaList(myArray);
 * 

 *
 * 
New elements of the appropriate Map type are
 *    automatically populated:

 *
 * 

 *    // get(index) automatically grows the list
 *    DynaBean newElement = (DynaBean)lazyList.get(lazyList.size());
 *    newElement.put("someProperty", "someValue");
 * 

 *
 * 
Once you've finished you can get back an Array of the
 *    elements of the appropriate type:

 *
 * 

 *    // Retrieve the array from the list
 *    TreeMap[] myArray = (TreeMap[])lazyList.toArray());
 * 

 *
 *
 * 
Example 2

 * 
Alternatively you can create an empty List and
 *    specify the Class for List's elements. The LazyDynaList
 *    uses the Class to automatically populate elements:

 *
 * 

 *    // e.g. For Maps
 *    List lazyList = new LazyDynaList(TreeMap.class);
 *
 *    // e.g. For POJO Beans
 *    List lazyList = new LazyDynaList(MyPojo.class);
 *
 *    // e.g. For DynaBeans
 *    List lazyList = new LazyDynaList(MyDynaBean.class);
 * 

 *
 * 
Example 3

 * 
Alternatively you can create an empty List and specify the
 *    DynaClass for List's elements. The LazyDynaList uses
 *    the DynaClass to automatically populate elements:

 *
 * 

 *    // e.g. For Maps
 *    DynaClass dynaClass = new LazyDynaMap(new HashMap());
 *    List lazyList = new LazyDynaList(dynaClass);
 *
 *    // e.g. For POJO Beans
 *    DynaClass dynaClass = (new WrapDynaBean(myPojo)).getDynaClass();
 *    List lazyList = new LazyDynaList(dynaClass);
 *
 *    // e.g. For DynaBeans
 *    DynaClass dynaClass = new BasicDynaClass(properties);
 *    List lazyList = new LazyDynaList(dynaClass);
 * 

 *
 * 
N.B. You may wonder why control the type
 *    using a DynaClass rather than the Class
 *    as in the previous example - the reason is that some DynaBean
 *    implementations don't have a default empty constructor and
 *    therefore need to be instantiated using the DynaClass.newInstance()
 *    method.

 *
 * 
Example 4

 * 
A slight variation - set the element type using either
 *    the setElementType(Class) method or the
 *    setElementDynaClass(DynaClass) method - then populate
 *    with the normal java.util.List methods(i.e.
 *    add(), addAll() or set()).

 *
 * 

 *    // Create a new LazyDynaList (100 element capacity)
 *    LazyDynaList lazyList = new LazyDynaList(100);
 *
 *    // Either Set the element type...
 *    lazyList.setElementType(TreeMap.class);
 *
 *    // ...or the element DynaClass...
 *    lazyList.setElementDynaClass(new MyCustomDynaClass());
 *
 *    // Populate from a collection
 *    lazyList.addAll(myCollection);
 *
 * 

 *
 * @version $Id$
 * @since 1.8.0
 */
public class LazyDynaList extends ArrayList {

    /**
     * The DynaClass of the List's elements.
     */
    private DynaClass elementDynaClass;

    /**
     * The WrapDynaClass if the List's contains
     * POJO Bean elements.
     *
     * N.B. WrapDynaClass isn't serlializable, which
     *      is why its stored separately in a
     *      transient instance variable.
     */
    private transient WrapDynaClass wrapDynaClass;

    /**
     * The type of the List's elements.
     */
    private Class elementType;

    /**
     * The DynaBean type of the List's elements.
     */
    private Class elementDynaBeanType;


    // ------------------- Constructors ------------------------------

    /**
     * Default Constructor.
     */
    public LazyDynaList() {
        super();
    }

    /**
     * Construct a LazyDynaList with the
     * specified capacity.
     *
     * @param capacity The initial capacity of the list.
     */
    public LazyDynaList(final int capacity) {
        super(capacity);

    }

    /**
     * Construct a  LazyDynaList with a
     * specified DynaClass for its elements.
     *
     * @param elementDynaClass The DynaClass of the List's elements.
     */
    public LazyDynaList(final DynaClass elementDynaClass) {
        super();
        setElementDynaClass(elementDynaClass);
    }

    /**
     * Construct a  LazyDynaList with a
     * specified type for its elements.
     *
     * @param elementType The Type of the List's elements.
     */
    public LazyDynaList(final Class elementType) {
        super();
        setElementType(elementType);
    }

    /**
     * Construct a  LazyDynaList populated with the
     * elements of a Collection.
     *
     * @param collection The Collection to populate the List from.
     */
    public LazyDynaList(final Collection collection) {
        super(collection.size());
        addAll(collection);
    }

    /**
     * Construct a  LazyDynaList populated with the
     * elements of an Array.
     *
     * @param array The Array to populate the List from.
     */
    public LazyDynaList(final Object[] array) {
        super(array.length);
        for (Object element : array) {
            add(element);
        }
    }


    // ------------------- java.util.List Methods --------------------

    /**
     * 
Insert an element at the specified index position.

     *
     * 
If the index position is greater than the current
     *    size of the List, then the List is automatically
     *    grown to the appropriate size.

     *
     * @param index The index position to insert the new element.
     * @param element The new element to add.
     */
    @Override
    public void add(final int index, final Object element) {

        final DynaBean dynaBean = transform(element);

        growList(index);

        super.add(index, dynaBean);

    }

    /**
     * 
Add an element to the List.

     *
     * @param element The new element to add.
     * @return true.
     */
    @Override
    public boolean add(final Object element) {

        final DynaBean dynaBean = transform(element);

        return super.add(dynaBean);

    }

    /**
     * 
Add all the elements from a Collection to the list.
     *
     * @param collection The Collection of new elements.
     * @return true if elements were added.
     */
    @Override
    public boolean addAll(final Collection collection) {

        if (collection == null || collection.size() == 0) {
            return false;
        }

        ensureCapacity(size() + collection.size());

        for (final Object e : collection) {
            add(e);
        }

        return true;

    }

    /**
     * 
Insert all the elements from a Collection into the
     *    list at a specified position.
     *
     * 
If the index position is greater than the current
     *    size of the List, then the List is automatically
     *    grown to the appropriate size.

     *
     * @param collection The Collection of new elements.
     * @param index The index position to insert the new elements at.
     * @return true if elements were added.
     */
    @Override
    public boolean addAll(final int index, final Collection collection) {

        if (collection == null || collection.size() == 0) {
            return false;
        }

        ensureCapacity((index > size() ? index : size()) + collection.size());

        // Call "transform" with first element, before
        // List is "grown" to ensure the correct DynaClass
        // is set.
        if (size() == 0) {
            transform(collection.iterator().next());
        }

        growList(index);

        int currentIndex = index;
        for (final Object e : collection) {
            add(currentIndex++, e);
        }

        return true;

    }

    /**
     * 
Return the element at the specified position.

     *
     * 
If the position requested is greater than the current
     *    size of the List, then the List is automatically
     *    grown (and populated) to the appropriate size.

     *
     * @param index The index position to insert the new elements at.
     * @return The element at the specified position.
     */
    @Override
    public Object get(final int index) {

        growList(index + 1);

        return super.get(index);

    }

    /**
     * 
Set the element at the specified position.

     *
     * 
If the position requested is greater than the current
     *    size of the List, then the List is automatically
     *    grown (and populated) to the appropriate size.

     *
     * @param index The index position to insert the new element at.
     * @param element The new element.
     * @return The new element.
     */
    @Override
    public Object set(final int index, final Object element) {

        final DynaBean dynaBean = transform(element);

        growList(index + 1);

        return super.set(index, dynaBean);

    }

    /**
     * 
Converts the List to an Array.

     *
     * 
The type of Array created depends on the contents
     *    of the List:

     * 
    
     *    
  • If the List contains only LazyDynaMap type elements
     *        then a java.util.Map[] array will be created.
    • 
     *    
  • If the List contains only elements which are
     *        "wrapped" DynaBeans then an Object[] of the most
     *        suitable type will be created.
    • 
     *    
  • ...otherwise a DynaBean[] will be created.
    • 
     *
     * @return An Array of the elements in this List.
     */
    @Override
    public Object[] toArray() {

        if (size() == 0 && elementType == null) {
            return new LazyDynaBean[0];
        }

        final Object[] array = (Object[])Array.newInstance(elementType, size());
        for (int i = 0; i < size(); i++) {
            if (Map.class.isAssignableFrom(elementType)) {
                array[i] = ((LazyDynaMap)get(i)).getMap();
            } else if (DynaBean.class.isAssignableFrom(elementType)) {
                array[i] = get(i);
            } else {
                array[i] = ((WrapDynaBean)get(i)).getInstance();
            }
        }
        return array;

    }

    /**
     * 
    Converts the List to an Array of the specified type.
    
     *
     * @param  The type of the array elements
     * @param model The model for the type of array to return
     * @return An Array of the elements in this List.
     */
    @Override
    public  T[] toArray(final T[] model) {

        final Class arrayType = model.getClass().getComponentType();
        if ((DynaBean.class.isAssignableFrom(arrayType))
                || (size() == 0 && elementType == null)) {
            return super.toArray(model);
        }

        if ((arrayType.isAssignableFrom(elementType))) {
            T[] array;
            if (model.length >= size()) {
                array = model;
            } else {
                @SuppressWarnings("unchecked")
                final
                // This is safe because we know the element type
                T[] tempArray = (T[]) Array.newInstance(arrayType, size());
                array = tempArray;
            }

            for (int i = 0; i < size(); i++) {
                Object elem;
                if (Map.class.isAssignableFrom(elementType)) {
                    elem = ((LazyDynaMap) get(i)).getMap();
                } else if (DynaBean.class.isAssignableFrom(elementType)) {
                    elem = get(i);
                } else {
                    elem = ((WrapDynaBean) get(i)).getInstance();
                }
                Array.set(array, i, elem);
            }
            return array;
        }

        throw new IllegalArgumentException("Invalid array type: "
                  + arrayType.getName() + " - not compatible with '"
                  + elementType.getName());

    }


    // ------------------- Public Methods ----------------------------

    /**
     * 
    Converts the List to an DynaBean Array.
    
     *
     * @return A DynaBean[] of the elements in this List.
     */
    public DynaBean[] toDynaBeanArray() {

        if (size() == 0 && elementDynaBeanType == null) {
            return new LazyDynaBean[0];
        }

        final DynaBean[] array = (DynaBean[])Array.newInstance(elementDynaBeanType, size());
        for (int i = 0; i < size(); i++) {
            array[i] = (DynaBean)get(i);
        }
        return array;

    }

    /**
     * 
    Set the element Type and DynaClass.
    
     *
     * @param elementType The type of the elements.
     * @throws IllegalArgumentException if the List already
     *            contains elements or the DynaClass is null.
     */
    public void setElementType(final Class elementType) {

        if (elementType == null) {
            throw new IllegalArgumentException("Element Type is missing");
        }

        final boolean changeType = (this.elementType != null && !this.elementType.equals(elementType));
        if (changeType && size() > 0) {
            throw new IllegalStateException("Element Type cannot be reset");
        }

        this.elementType = elementType;

        // Create a new object of the specified type
        Object object = null;
        try {
            object = elementType.newInstance();
        } catch (final Exception e) {
            throw new IllegalArgumentException("Error creating type: "
                           + elementType.getName() + " - " + e);
        }

        // Create a DynaBean
        DynaBean dynaBean = null;
        if (Map.class.isAssignableFrom(elementType)) {
            dynaBean = createDynaBeanForMapProperty(object);
            this.elementDynaClass = dynaBean.getDynaClass();
        } else if (DynaBean.class.isAssignableFrom(elementType)) {
            dynaBean = (DynaBean)object;
            this.elementDynaClass = dynaBean.getDynaClass();
        } else {
            dynaBean = new WrapDynaBean(object);
            this.wrapDynaClass = (WrapDynaClass)dynaBean.getDynaClass();
        }

        this.elementDynaBeanType = dynaBean.getClass();

        // Re-calculate the type
        if (WrapDynaBean.class.isAssignableFrom(elementDynaBeanType )) {
            this.elementType = ((WrapDynaBean)dynaBean).getInstance().getClass();
        } else if (LazyDynaMap.class.isAssignableFrom(elementDynaBeanType )) {
            this.elementType = ((LazyDynaMap)dynaBean).getMap().getClass();
        }

    }

    /**
     * 
    Set the element Type and DynaClass.
    
     *
     * @param elementDynaClass The DynaClass of the elements.
     * @throws IllegalArgumentException if the List already
     *            contains elements or the DynaClass is null.
     */
    public void setElementDynaClass(final DynaClass elementDynaClass) {

        if (elementDynaClass == null) {
            throw new IllegalArgumentException("Element DynaClass is missing");
        }

        if (size() > 0) {
            throw new IllegalStateException("Element DynaClass cannot be reset");
        }

        // Try to create a new instance of the DynaBean
        try {
            final DynaBean dynaBean  = elementDynaClass.newInstance();
            this.elementDynaBeanType = dynaBean.getClass();
            if (WrapDynaBean.class.isAssignableFrom(elementDynaBeanType)) {
                this.elementType = ((WrapDynaBean)dynaBean).getInstance().getClass();
                this.wrapDynaClass = (WrapDynaClass)elementDynaClass;
            } else if (LazyDynaMap.class.isAssignableFrom(elementDynaBeanType)) {
                this.elementType = ((LazyDynaMap)dynaBean).getMap().getClass();
                this.elementDynaClass = elementDynaClass;
            } else {
                this.elementType = dynaBean.getClass();
                this.elementDynaClass = elementDynaClass;
            }
        } catch (final Exception e) {
            throw new IllegalArgumentException(
                        "Error creating DynaBean from " +
                        elementDynaClass.getClass().getName() + " - " + e);
        }

    }


    // ------------------- Private Methods ---------------------------

    /**
     * 
    Automatically grown the List
     *    to the appropriate size, populating with
     *    DynaBeans.
    
     *
     * @param requiredSize the required size of the List.
     */
    private void growList(final int requiredSize) {

        if (requiredSize < size()) {
            return;
        }

        ensureCapacity(requiredSize + 1);

        for (int i = size(); i < requiredSize; i++) {
            final DynaBean dynaBean = transform(null);
            super.add(dynaBean);
        }

    }

    /**
     * 
    Transform the element into a DynaBean:
    
     *
     *