org.h2.index.RangeCursor Maven / Gradle / Ivy
/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.index;
import org.h2.engine.Session;
import org.h2.message.DbException;
import org.h2.result.Row;
import org.h2.result.SearchRow;
import org.h2.value.Value;
import org.h2.value.ValueLong;
/**
* The cursor implementation for the range index.
*/
class RangeCursor implements Cursor {
private final Session session;
private boolean beforeFirst;
private long current;
private Row currentRow;
private final long start, end, step;
RangeCursor(Session session, long start, long end) {
this(session, start, end, 1);
}
RangeCursor(Session session, long start, long end, long step) {
this.session = session;
this.start = start;
this.end = end;
this.step = step;
beforeFirst = true;
}
@Override
public Row get() {
return currentRow;
}
@Override
public SearchRow getSearchRow() {
return currentRow;
}
@Override
public boolean next() {
if (beforeFirst) {
beforeFirst = false;
current = start;
} else {
current += step;
}
currentRow = session.createRow(new Value[]{ValueLong.get(current)}, 1);
return step > 0 ? current <= end : current >= end;
}
@Override
public boolean previous() {
throw DbException.throwInternalError(toString());
}
}