/*
* 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 Software Foundation, Inc.
* 59 Temple Place, Suite 330
* Boston, MA 02111-1307 USA
*
* @author Scott Ferguson
*/
package com.caucho.amber.expr;
import com.caucho.amber.query.FromItem;
import com.caucho.amber.query.QueryParser;
import com.caucho.amber.table.AmberColumn;
import com.caucho.util.CharBuffer;
import java.util.ArrayList;
/**
* Links two tables by their key fields.
*/
public class EqualJoinExpr extends JoinExpr {
private ArrayList<AmberColumn> _keyColumns;
private FromItem _fromItemA;
private FromItem _fromItemB;
/**
* Creates the expr.
*/
EqualJoinExpr(ArrayList<AmberColumn> keyColumns,
FromItem fromItemA,
FromItem fromItemB)
{
_keyColumns = keyColumns;
_fromItemA = fromItemA;
_fromItemB = fromItemB;
if (fromItemA == null || fromItemB == null)
throw new NullPointerException();
}
/**
* Returns true for a boolean expression.
*/
public boolean isBoolean()
{
return true;
}
/**
* Binds the expression as a select item.
*/
public AmberExpr bindSelect(QueryParser parser)
{
return this;
}
/**
* Binds the link to the from item.
*/
public boolean bindToFromItem()
{
if (_fromItemA.getJoinExpr() == null ||
_fromItemA.getJoinExpr().equals(this)) {
_fromItemA.setJoinExpr(this);
return true;
}
else if (_fromItemB.getJoinExpr() == null) {
_fromItemB.setJoinExpr(this);
return true;
}
else
return false;
}
/**
* Returns the parent join clause.
*/
public FromItem getJoinTarget()
{
return _fromItemA;
}
/**
* Returns the id expr with the joined expression.
*/
public AmberExpr replace(IdFieldExpr id)
{
IdExpr parent = (IdExpr) id.getParent();
if (parent.getFromItem() == _fromItemA)
return new ColumnExpr(new IdExpr(_fromItemA), id.getColumn());
else if (parent.getFromItem() == _fromItemB)
return new ColumnExpr(new IdExpr(_fromItemB), id.getColumn());
else
return id;
}
/**
* Returns the id expr with the joined expression.
*/
public AmberExpr replace(IdExpr id)
{
return id;
}
/**
* Generates the where expression.
*/
public void generateWhere(CharBuffer cb)
{
generateInternalWhere(cb, true);
}
/**
* Generates the (update) where expression.
*/
public void generateUpdateWhere(CharBuffer cb)
{
generateInternalWhere(cb, false);
}
/**
* Generates the having expression.
*/
public void generateHaving(CharBuffer cb)
{
generateWhere(cb);
}
/**
* Test for equality.
*/
public boolean equals(Object o)
{
if (! (o instanceof EqualJoinExpr))
return false;
EqualJoinExpr equalExpr = (EqualJoinExpr) o;
return (_keyColumns.equals(equalExpr._keyColumns) &&
_fromItemA.equals(equalExpr._fromItemA) &&
_fromItemB.equals(equalExpr._fromItemB));
}
public String toString()
{
return ("EqualJoinExpr[" + _keyColumns + "," +
_fromItemA + "," + _fromItemB + "]");
}
//
// private
private void generateInternalWhere(CharBuffer cb,
boolean select)
{
cb.append('(');
for (int i = 0; i < _keyColumns.size(); i++) {
AmberColumn column = _keyColumns.get(i);
if (i != 0)
cb.append(" AND ");
cb.append(_fromItemA.getName());
cb.append('.');
cb.append(column.getName());
cb.append('=');
cb.append(_fromItemB.getName());
cb.append('.');
cb.append(column.getName());
}
cb.append('(');
}
}