/*
* Copyright (c) 1998-2011 Caucho Technology -- all rights reserved
*
* This file is part of Resin(R) Open Source
*
* Each copy or derived work must preserve the copyright notice and this
* notice unmodified.
*
* Resin Open Source is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Resin Open Source 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, or any warranty
* of NON-INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with Resin Open Source; if not, write to the
* Free SoftwareFoundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.db.sql;
import com.caucho.db.table.TableIterator;
import java.io.IOException;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.logging.Logger;
class LeftOuterJoinExpr extends RowIterateExpr {
private Expr _expr;
private FromItem _table;
private int _tableIndex;
LeftOuterJoinExpr(FromItem table, Expr expr)
{
_table = table;
_expr = expr;
}
/**
* Returns the expected result type of the expression.
*/
public Class getType()
{
return boolean.class;
}
/**
* Returns the cost based on the given FromList.
*/
public long subCost(ArrayList<FromItem> fromList)
{
if (! fromList.contains(_table))
return Integer.MAX_VALUE;
else if (fromList.get(fromList.size() - 1) == _table)
return 0;
else
return 100 * 100;
}
/**
* Returns an index expression if available.
*/
@Override
public RowIterateExpr getIndexExpr(FromItem fromItem)
{
if (_table == fromItem) {
RowIterateExpr indexExpr = _expr.getIndexExpr(fromItem);
if (indexExpr != null)
return new LeftOuterIndexExpr(indexExpr);
else
return this;
}
else
return null;
}
/**
* Binds the expression.
*/
@Override
public Expr bind(Query query)
throws SQLException
{
_expr = _expr.bind(query);
FromItem []fromItems = query.getFromItems();
for (int i = 0; i < fromItems.length; i++) {
if (_table == fromItems[i])
_tableIndex = i;
}
return this;
}
/**
* Sets the initial row.
*/
boolean init(QueryContext context, TableIterator rowIter)
throws SQLException, IOException
{
rowIter.init(context);
if (! rowIter.next()) {
return false;
}
return true;
}
/**
* Sets the initial row.
*/
@Override
boolean initRow(QueryContext context, TableIterator rowIter)
throws SQLException, IOException
{
rowIter.init(context);
if (! rowIter.next())
return false;
rowIter.initRow();
Expr expr = _expr;
do {
if (rowIter.nextRow()) {
}
else if (rowIter.next()) {
rowIter.initRow();
}
else {
rowIter.initNullRow();
return true;
}
} while (expr.evalBoolean(context) != TRUE);
TableIterator parentIter = context.getTableIterators()[1];
return true;
}
/**
* Returns true if shifing the child rows will make a difference.
*/
boolean allowChildRowShift(QueryContext context, TableIterator rowIter)
{
return false;
}
/**
* Returns the next row.
*/
boolean nextRow(QueryContext context, TableIterator rowIter)
throws IOException, SQLException
{
if (rowIter.isNullRow())
return false;
else {
Expr expr = _expr;
while (rowIter.nextRow() || rowIter.next()) {
if (expr.evalBoolean(context) == TRUE) {
return true;
}
}
return false;
}
}
/**
* Returns the next row.
*/
boolean nextBlock(QueryContext context, TableIterator rowIter)
throws IOException
{
return false;
}
public String toString()
{
return "LeftOuterJoinExpr(" + _expr + ")";
}
}