org.h2.index.PageBtreeCursor 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 org.h2.engine.Session;
import org.h2.result.Row;
import org.h2.result.SearchRow;
/**
* The cursor implementation for the page b-tree index.
*/
public class PageBtreeCursor implements Cursor {
private final Session session;
private final PageBtreeIndex index;
private final SearchRow last;
private PageBtreeLeaf current;
private int i;
private SearchRow currentSearchRow;
private Row currentRow;
PageBtreeCursor(Session session, PageBtreeIndex index, SearchRow last) {
this.session = session;
this.index = index;
this.last = last;
}
/**
* Set the position of the current row.
*
* @param current the leaf page
* @param i the index within the page
*/
void setCurrent(PageBtreeLeaf current, int i) {
this.current = current;
this.i = i;
}
@Override
public Row get() {
if (currentRow == null && currentSearchRow != null) {
currentRow = index.getRow(session, currentSearchRow.getKey());
}
return currentRow;
}
@Override
public SearchRow getSearchRow() {
return currentSearchRow;
}
@Override
public boolean next() {
if (current == null) {
return false;
}
if (i >= current.getEntryCount()) {
current.nextPage(this);
if (current == null) {
return false;
}
}
currentSearchRow = current.getRow(i);
currentRow = null;
if (last != null && index.compareRows(currentSearchRow, last) > 0) {
currentSearchRow = null;
return false;
}
i++;
return true;
}
@Override
public boolean previous() {
if (current == null) {
return false;
}
if (i < 0) {
current.previousPage(this);
if (current == null) {
return false;
}
}
currentSearchRow = current.getRow(i);
currentRow = null;
i--;
return true;
}
}