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/*
Copyright (c) 2008 Health Market Science, Inc.
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; either
version 2.1 of the License, or (at your option) any later version.
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
You can contact Health Market Science at info@healthmarketscience.com
or at the following address:
Health Market Science
2700 Horizon Drive
Suite 200
King of Prussia, PA 19406
*/
package com.healthmarketscience.jackcess;
import java.io.IOException;
import java.util.List;
/**
* Simple implementation of an Access table index
* @author Tim McCune
*/
public class SimpleIndex extends Index {
/** data for the single index page. if this data came from multiple pages,
the index is read-only. */
private SimpleDataPage _dataPage;
public SimpleIndex(Table table, int uniqueEntryCount,
int uniqueEntryCountOffset)
{
super(table, uniqueEntryCount, uniqueEntryCountOffset);
}
@Override
protected void updateImpl() throws IOException {
writeDataPage(_dataPage);
}
@Override
protected void readIndexEntries()
throws IOException
{
// find first leaf page
int nextPageNumber = getRootPageNumber();
SimpleDataPage indexPage = null;
while(true) {
indexPage = new SimpleDataPage(nextPageNumber);
readDataPage(indexPage);
if(!indexPage.isLeaf()) {
// FIXME we can't modify this index at this point in time
setReadOnly();
// found another node page
if(!indexPage.getEntries().isEmpty()) {
nextPageNumber = indexPage.getEntries().get(0).getSubPageNumber();
} else {
// try tail page
nextPageNumber = indexPage.getChildTailPageNumber();
}
indexPage = null;
} else {
// found first leaf
break;
}
}
// save the first leaf page
_dataPage = indexPage;
nextPageNumber = indexPage.getNextPageNumber();
_dataPage.setNextPageNumber(INVALID_INDEX_PAGE_NUMBER);
indexPage = null;
// read all leaf pages.
while(nextPageNumber != INVALID_INDEX_PAGE_NUMBER) {
// FIXME we can't modify this index at this point in time
setReadOnly();
// found another one
indexPage = new SimpleDataPage(nextPageNumber);
readDataPage(indexPage);
// since we read all the entries in sort order, we can insert them
// directly into the entries list
_dataPage.getEntries().addAll(indexPage.getEntries());
int totalSize = (_dataPage.getTotalEntrySize() +
indexPage.getTotalEntrySize());
_dataPage.setTotalEntrySize(totalSize);
nextPageNumber = indexPage.getNextPageNumber();
}
// check the entry order, just to be safe
List<Entry> entries = _dataPage.getEntries();
for(int i = 0; i < (entries.size() - 1); ++i) {
Entry e1 = entries.get(i);
Entry e2 = entries.get(i + 1);
if(e1.compareTo(e2) > 0) {
throw new IOException("Unexpected order in index entries, " +
e1 + " is greater than " + e2);
}
}
}
@Override
protected DataPage findDataPage(Entry entry)
throws IOException
{
return _dataPage;
}
@Override
protected DataPage getDataPage(int pageNumber)
throws IOException
{
throw new UnsupportedOperationException();
}
/**
* Simple implementation of a DataPage
*/
private static final class SimpleDataPage extends DataPage {
private final int _pageNumber;
private boolean _leaf;
private int _nextPageNumber;
private int _totalEntrySize;
private int _childTailPageNumber;
private List<Entry> _entries;
private SimpleDataPage(int pageNumber) {
_pageNumber = pageNumber;
}
@Override
public int getPageNumber() {
return _pageNumber;
}
@Override
public boolean isLeaf() {
return _leaf;
}
@Override
public void setLeaf(boolean isLeaf) {
_leaf = isLeaf;
}
@Override
public int getPrevPageNumber() { return 0; }
@Override
public void setPrevPageNumber(int pageNumber) {
// ignored
}
@Override
public int getNextPageNumber() {
return _nextPageNumber;
}
@Override
public void setNextPageNumber(int pageNumber) {
_nextPageNumber = pageNumber;
}
@Override
public int getChildTailPageNumber() {
return _childTailPageNumber;
}
@Override
public void setChildTailPageNumber(int pageNumber) {
_childTailPageNumber = pageNumber;
}
@Override
public int getTotalEntrySize() {
return _totalEntrySize;
}
@Override
public void setTotalEntrySize(int totalSize) {
_totalEntrySize = totalSize;
}
@Override
public byte[] getEntryPrefix() {
return EMPTY_PREFIX;
}
@Override
public void setEntryPrefix(byte[] entryPrefix) {
// ignored
}
@Override
public List<Entry> getEntries() {
return _entries;
}
@Override
public void setEntries(List<Entry> entries) {
_entries = entries;
}
@Override
public void addEntry(int idx, Entry entry) {
_entries.add(idx, entry);
_totalEntrySize += entry.size();
}
@Override
public void removeEntry(int idx) {
Entry oldEntry = _entries.remove(idx);
_totalEntrySize -= oldEntry.size();
}
}
}
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