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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.cayenne.access.jdbc;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.cayenne.CayenneException;
import org.apache.cayenne.access.ResultIterator;
import org.apache.cayenne.map.DbEntity;
/**
* @since 3.0
*/
public class LimitResultIterator implements ResultIterator {
protected ResultIterator wrappedIterator;
protected Map<String, Object> nextDataObjectIds;
protected int fetchLimit;
protected int offset;
protected int fetchedSoFar;
protected boolean nextRow;
public LimitResultIterator(ResultIterator wrappedIterator, int offset, int fetchLimit)
throws CayenneException {
if (wrappedIterator == null) {
throw new CayenneException("Null wrapped iterator.");
}
this.wrappedIterator = wrappedIterator;
this.offset = offset;
this.fetchLimit = fetchLimit;
checkOffset();
checkNextRow();
}
private void checkOffset() throws CayenneException {
for (int i = 0; i < offset && wrappedIterator.hasNextRow(); i++) {
wrappedIterator.nextDataRow();
}
}
private void checkNextRow() throws CayenneException {
nextRow = false;
if ((fetchLimit <= 0 || fetchedSoFar < fetchLimit)
&& this.wrappedIterator.hasNextRow()) {
nextRow = true;
fetchedSoFar++;
}
}
protected Map readDataRow() throws CayenneException {
Map<String, Object> next = wrappedIterator.nextDataRow();
return next;
}
public void close() throws CayenneException {
wrappedIterator.close();
}
public List dataRows(boolean close) throws CayenneException {
List<Map> list = new ArrayList<Map>();
try {
while (this.hasNextRow()) {
list.add(this.nextDataRow());
}
return list;
}
finally {
if (close) {
close();
}
}
}
public int getDataRowWidth() {
return wrappedIterator.getDataRowWidth();
}
public boolean hasNextRow() throws CayenneException {
return nextRow;
}
public Map nextDataRow() throws CayenneException {
if (!hasNextRow()) {
throw new CayenneException(
"An attempt to read uninitialized row or past the end of the iterator.");
}
Map<String, Object> row = readDataRow();
checkNextRow();
return row;
}
public Object nextId(DbEntity entity) throws CayenneException {
if (!hasNextRow()) {
throw new CayenneException(
"An attempt to read uninitialized row or past the end of the iterator.");
}
Object id = readId(entity);
checkNextId(entity);
return id;
}
public Map<String, Object> nextObjectId(DbEntity entity) throws CayenneException {
if (!hasNextRow()) {
throw new CayenneException(
"An attempt to read uninitialized row or past the end of the iterator.");
}
checkNextObjectId(entity);
return nextDataObjectIds;
}
public void skipDataRow() throws CayenneException {
wrappedIterator.skipDataRow();
}
void checkNextId(DbEntity entity) throws CayenneException {
if (entity == null) {
throw new CayenneException("Null DbEntity, can't create id.");
}
nextRow = false;
if (wrappedIterator.hasNextRow()) {
nextRow = true;
}
}
public Object readId(DbEntity entity) throws CayenneException {
Object next = wrappedIterator.nextId(entity);
return next;
}
void checkNextObjectId(DbEntity entity) throws CayenneException {
if (entity == null) {
throw new CayenneException("Null DbEntity, can't create id.");
}
nextRow = false;
nextDataObjectIds = null;
if (wrappedIterator.hasNextRow()) {
nextRow = true;
Map<String, Object> next = wrappedIterator.nextObjectId(entity);
nextDataObjectIds = next;
}
}
}