package com.rometools.rome.feed.synd;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.List;
import com.rometools.rome.feed.module.DCSubject;
/**
* List implementation for SyndCategoryImpl elements. To be directly used by the SyndFeedImpl and
* SyndEntryImpl classes only.
* <p>
* It acts as a facade on top of the DCSubjectImpl elements of the underlying list and remains in
* synch with it. It is possible to work on either list, the categories one or the subjects one and
* they remain in synch.
* <p>
* This is necessary because the SyndFeedImpl categories are just a convenience to access the
* DublinCore subjects.
* <P>
* All this mess to avoid making DCSubjectImpl implement SyndCategory (which it would be odd).
* <p>
*
* @author Alejandro Abdelnur
*
*/
class SyndCategoryListFacade extends AbstractList<SyndCategory> {
private final List<DCSubject> subjects;
/**
* Default constructor. Creates and empty list.
*/
public SyndCategoryListFacade() {
this(new ArrayList<DCSubject>());
}
/**
* Creates a facade list of categories on top the given subject list.
* <P>
*
* @param subjects the list of subjects to create the facade.
*
*/
public SyndCategoryListFacade(final List<DCSubject> subjects) {
this.subjects = subjects;
}
/**
* Gets the category by index.
* <p>
*
* @param index the index position to retrieve the category.
* @return the SyndCategoryImpl in position index, <b>null</b> if none.
*
*/
@Override
public SyndCategory get(final int index) {
return new SyndCategoryImpl(subjects.get(index));
}
/**
* Returns the size of the list.
* <p>
*
* @return the size of the list.
*
*/
@Override
public int size() {
return subjects.size();
}
/**
* Sets a category in an existing position in the list.
* <p>
*
* @param index position to set the category.
* @param obj the SyndCategoryImpl object to set.
* @return the SyndCategoryImpl object that is being replaced, <b>null</b> if none.
*
*/
@Override
public SyndCategory set(final int index, final SyndCategory obj) {
final SyndCategoryImpl sCat = (SyndCategoryImpl) obj;
DCSubject subject;
if (sCat != null) {
subject = sCat.getSubject();
} else {
subject = null;
}
subject = subjects.set(index, subject);
if (subject != null) {
return new SyndCategoryImpl(subject);
} else {
return null;
}
}
/**
* Adds a category to the list.
* <p>
*
* @param index position to add the category.
* @param obj the SyndCategoryImpl object to add.
*
*/
@Override
public void add(final int index, final SyndCategory obj) {
final SyndCategoryImpl sCat = (SyndCategoryImpl) obj;
DCSubject subject;
if (sCat != null) {
subject = sCat.getSubject();
} else {
subject = null;
}
subjects.add(index, subject);
}
/**
* Removes a category element from a specific position.
* <p>
*
* @param index position to remove the category from.
* @return the SyndCategoryImpl being removed from position index, <b>null</b> if none.
*
*/
@Override
public SyndCategory remove(final int index) {
final DCSubject subject = subjects.remove(index);
if (subject != null) {
return new SyndCategoryImpl(subject);
} else {
return null;
}
}
/**
* Returns a list with the DCSubject elements of the SyndCategoryImpl list facade. To be used by
* the SyndFeedImpl class only.
* <p>
*
* @param cList the list with SyndCategoryImpl elements to convert to subject list.
* @return a list with DCSubject elements corresponding to the categories in the given list.
*
*/
public static List<DCSubject> convertElementsSyndCategoryToSubject(final List<SyndCategory> cList) {
List<DCSubject> sList = null;
if (cList != null) {
sList = new ArrayList<DCSubject>();
for (int i = 0; i < cList.size(); i++) {
final SyndCategoryImpl sCat = (SyndCategoryImpl) cList.get(i);
DCSubject subject = null;
if (sCat != null) {
subject = sCat.getSubject();
}
sList.add(subject);
}
}
return sList;
}
}