/*

  * PrimitiveArrayTransform.java May 2007

  *

  * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>

  *

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

  * modify it under the terms of the GNU Lesser General Public

  * License as published by the Free Software Foundation.

  *

  * This library 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 Lesser General Public License for more details.

  *

  * You should have received a copy of the GNU Lesser General 

  * Public License along with this library; if not, write to the 

  * Free Software Foundation, Inc., 59 Temple Place, Suite 330, 

  * Boston, MA  02111-1307  USA

  */

 package org.simpleframework.xml.transform;

 import org.simpleframework.xml.transform.StringArrayTransform;

 import java.lang.reflect.Array;

 /**

  * The <code>PrimitiveArrayTransform</code> is used to transform 

  * arrays to and from string representations, which will be inserted

  * in the generated XML document as the value place holder. The

  * value must be readable and writable in the same format. Fields

  * and methods annotated with the XML attribute annotation will use

  * this to persist and retrieve the value to and from the XML source.

  * <pre>

  * 

  *    @Attribute

  *    private int[] text;

  *    

  * </pre>

  * As well as the XML attribute values using transforms, fields and

  * methods annotated with the XML element annotation will use this.

  * Aside from the obvious difference, the element annotation has an

  * advantage over the attribute annotation in that it can maintain

  * any references using the <code>CycleStrategy</code> object. 

  * 

  * @author Niall Gallagher

  */

 class ArrayTransform implements Transform {           

    /**

     * This transform is used to split the comma separated values. 

     */

    private final StringArrayTransform split;        

    /**

     * This is the transform that performs the individual transform.

     */

    private final Transform delegate;

    /**

     * This is the entry type for the primitive array to be created.

     */

    private final Class entry;

    /**

     * Constructor for the <code>PrimitiveArrayTransform</code> object.

     * This is used to create a transform that will create primitive

     * arrays and populate the values of the array with values from a

     * comma separated list of individula values for the entry type.

     * 

     * @param delegate this is used to perform individual transforms

     * @param entry this is the entry component type for the array

     */

    public ArrayTransform(Transform delegate, Class entry) {

       this.split = new StringArrayTransform();

       this.delegate = delegate;

       this.entry = entry;

    }       

    /**

     * This method is used to convert the string value given to an

     * appropriate representation. This is used when an object is

     * being deserialized from the XML document and the value for

     * the string representation is required.

     * 

     * @param value this is the string representation of the value

     * 

     * @return this returns an appropriate instanced to be used

     */

    public Object read(String value) throws Exception {

       String[] list = split.read(value);      

       int length = list.length;

       return read(list, length);

    }

    /**

     * This method is used to convert the string value given to an

     * appropriate representation. This is used when an object is

     * being deserialized from the XML document and the value for

     * the string representation is required.

     * 

     * @param list this is the string representation of the value

     * @param length this is the number of string values to use

     * 

     * @return this returns an appropriate instanced to be used

     */

    private Object read(String[] list, int length) throws Exception {

       Object array = Array.newInstance(entry, length);

       for(int i = 0; i < length; i++) {

          Object item = delegate.read(list[i]);

          if(item != null) {

             Array.set(array, i, item);                 

          }         

       }

       return array;

    }

    /**

     * This method is used to convert the provided value into an XML

     * usable format. This is used in the serialization process when

     * there is a need to convert a field value in to a string so 

     * that that value can be written as a valid XML entity.

     * 

     * @param value this is the value to be converted to a string

     * 

     * @return this is the string representation of the given value

     */

    public String write(Object value) throws Exception {

       int length = Array.getLength(value);

       return write(value, length);      

    }

    /**

     * This method is used to convert the provided value into an XML

     * usable format. This is used in the serialization process when

     * there is a need to convert a field value in to a string so 

     * that that value can be written as a valid XML entity.

     * 

     * @param value this is the value to be converted to a string

     * 

     * @return this is the string representation of the given value

     */

    private String write(Object value, int length) throws Exception {

       String[] list = new String[length];

       for(int i = 0; i < length; i++) {

          Object entry = Array.get(value, i);

          if(entry != null) {

             list[i] = delegate.write(entry);                             

          }         

       }      

       return split.write(list);

    }

 }