/*
* 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.cocoon.components.search;
import org.apache.lucene.document.Document;
import org.apache.lucene.search.Hits;
import java.io.IOException;
import java.util.ArrayList;
import java.util.ListIterator;
import java.util.NoSuchElementException;
/**
* This class should help you to manage paging of hits.
*
* @author <a href="mailto:berni_huber@a1.net">Bernhard Huber</a>
* @version CVS $Id$
*/
public class LuceneCocoonPager implements ListIterator
{
/**
* Default count of hits per page.
*/
public final static int COUNT_OF_HITS_PER_PAGE_DEFAULT = 5;
/**
* Default starting index
*/
public final static int HITS_INDEX_START_DEFAULT = 0;
/**
* Current index of hit to return by next()
*/
int hitsIndex = HITS_INDEX_START_DEFAULT;
/**
* Maximum count of hits to return by next(), and previous()
*/
int countOfHitsPerPage = COUNT_OF_HITS_PER_PAGE_DEFAULT;
/**
* Hits to iterate upon
*/
private Hits hits;
/**
* @param hits Description of Parameter
*/
public LuceneCocoonPager(Hits hits) {
setHits(hits);
}
/**
* Constructor for the LuceneCocoonPager object
*/
public LuceneCocoonPager() {
}
/**
* Sets the hits attribute of the LuceneCocoonPager object
*
* @param hits The new hits value
*/
public void setHits(Hits hits) {
this.hits = hits;
this.hitsIndex = HITS_INDEX_START_DEFAULT;
}
/**
* Set count of hits displayed per single page
*
* @param countOfHitsPerPage The new countOfHitsPerPage value
*/
public void setCountOfHitsPerPage(int countOfHitsPerPage) {
this.countOfHitsPerPage = countOfHitsPerPage;
if (this.countOfHitsPerPage <= 0) {
this.countOfHitsPerPage = 1;
}
}
/**
* Get starting index for retrieving hits
*
* @param start_index The new startIndex value
*/
public void setStartIndex(int start_index) {
this.hitsIndex = start_index;
}
/**
* Replaces the last element returned by next or previous with the
* specified element (optional operation).
*
* @param o Description of Parameter
*/
public void set(Object o) {
throw new UnsupportedOperationException();
}
/**
* Get count of hits
*
* @return The count of hits
*/
public int getCountOfHits() {
return hits.length();
}
/**
* Get count of hits displayed per single page
*
* @return The countOfHitsPerPage value
*/
public int getCountOfHitsPerPage() {
return this.countOfHitsPerPage;
}
/**
* Caluclate count of pages for displaying all hits
*
* @return The countOfPages value
*/
public int getCountOfPages() {
int count_of_pages = hits.length() / this.countOfHitsPerPage;
int remainder = hits.length() % this.countOfHitsPerPage;
if (remainder != 0) {
count_of_pages += 1;
}
return count_of_pages;
}
/**
* Set starting index for retrieving hits
*
* @return The startIndex value
*/
public int getStartIndex() {
return this.hitsIndex;
}
/**
* Inserts the specified element into the list (optional operation).
*
* @param o Description of Parameter
* @exception UnsupportedOperationException Description of Exception
*/
public void add(Object o) throws UnsupportedOperationException {
throw new UnsupportedOperationException();
}
/**
* Returns true if this list iterator has more elements when traversing
* the list in the forward direction.
*
* @return Description of the Returned Value
*/
public boolean hasNext() {
return hitsIndex + countOfHitsPerPage < hits.length();
}
/**
* Returns true if this list iterator has more elements when traversing
* the list in the reverse direction.
*
* @return Description of the Returned Value
*/
public boolean hasPrevious() {
return hitsIndex >= countOfHitsPerPage;
}
/**
* Returns the next element in the list.
*
* @return Description of the Returned Value
*/
public Object next() {
ArrayList hitsPerPageList = new ArrayList();
int endIndex = Math.min(hits.length(), hitsIndex + countOfHitsPerPage);
//do not increment the actual hitsindex
int hits_copy = hitsIndex;
while (hits_copy < endIndex) {
try {
HitWrapper hit = new HitWrapper(hits.score(hits_copy), hits.doc(hits_copy));
hitsPerPageList.add(hit);
} catch (IOException ioe) {
throw new NoSuchElementException("no more hits: " + ioe.getMessage());
}
hits_copy++;
}
return hitsPerPageList;
}
/**
* Returns the index of the element that would be returned by a
* subsequent call to next.
*
* @return Description of the Returned Value
*/
public int nextIndex() {
return Math.min(hitsIndex + countOfHitsPerPage, hits.length() - 1);
}
/**
* Returns the previous element in the list.
*
* @return Description of the Returned Value
*/
public Object previous() {
ArrayList hitsPerPageList = new ArrayList();
int startIndex = Math.max(0, hitsIndex - countOfHitsPerPage);
int endIndex = Math.min(hits.length() - 1, hitsIndex - countOfHitsPerPage);
if (startIndex < endIndex) {
while (startIndex < endIndex) {
try {
HitWrapper hit = new HitWrapper(hits.score(startIndex),
hits.doc(startIndex));
hitsPerPageList.add(hit);
} catch (IOException ioe) {
throw new NoSuchElementException("no more hits: " + ioe.getMessage());
}
startIndex++;
}
hitsIndex = endIndex;
} else {
throw new NoSuchElementException();
}
return hitsPerPageList;
}
/**
* Returns the index of the element that would be returned by a
* subsequent call to previous.
*
* @return Description of the Returned Value
*/
public int previousIndex() {
return Math.max(0, hitsIndex - countOfHitsPerPage);
}
/**
* Removes from the list the last element that was returned by next or
* previous (optional operation).
*/
public void remove() {
throw new UnsupportedOperationException();
}
/**
* A helper class encapsulating found document, and its score
*
* @author <a href="mailto:berni_huber@a1.net">Bernhard Huber</a>
* @version CVS $Id$
*/
public static class HitWrapper {
float score;
Document document;
/**
* Constructor for the HitWrapper object
*
* @param score Description of Parameter
* @param document Description of Parameter
*/
public HitWrapper(float score, Document document) {
this.document = document;
this.score = score;
}
/**
* Gets the document attribute of the HitWrapper object
*
* @return The document value
*/
public Document getDocument() {
return document;
}
/**
* Gets the score attribute of the HitWrapper object
*
* @return The score value
*/
public float getScore() {
return score;
}
/**
* Gets the field attribute of the HitWrapper object
*
* @param field Description of Parameter
* @return The field value
*/
public String getField(String field) {
return document.get(field);
}
}
}