org.h2.index.ScanCursor Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.index;
import java.util.Iterator;
import org.h2.engine.Session;
import org.h2.message.DbException;
import org.h2.result.Row;
import org.h2.result.SearchRow;
/**
* The cursor implementation for the scan index.
*/
public class ScanCursor implements Cursor {
private final ScanIndex scan;
private Row row;
private final Session session;
private final boolean multiVersion;
private Iterator delta;
ScanCursor(Session session, ScanIndex scan, boolean multiVersion) {
this.session = session;
this.scan = scan;
this.multiVersion = multiVersion;
if (multiVersion) {
delta = scan.getDelta();
}
row = null;
}
@Override
public Row get() {
return row;
}
@Override
public SearchRow getSearchRow() {
return row;
}
@Override
public boolean next() {
if (multiVersion) {
while (true) {
if (delta != null) {
if (!delta.hasNext()) {
delta = null;
row = null;
continue;
}
row = delta.next();
if (!row.isDeleted() || row.getSessionId() == session.getId()) {
continue;
}
} else {
row = scan.getNextRow(row);
if (row != null && row.getSessionId() != 0 &&
row.getSessionId() != session.getId()) {
continue;
}
}
break;
}
return row != null;
}
row = scan.getNextRow(row);
return row != null;
}
@Override
public boolean previous() {
throw DbException.throwInternalError(toString());
}
}