/*
* 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.ForeignColumn;
import com.caucho.amber.table.LinkColumns;
import com.caucho.util.CharBuffer;
/**
* Links two tables.
*
* The parent table is "b" in "b.next".
* The child table is "b.next"
*
* The source is "b", i.e. the parent.
* The target is "b.next", i.e. the child.
*/
public class ManyToOneJoinExpr extends JoinExpr {
private LinkColumns _linkColumns;
private FromItem _sourceFromItem;
private FromItem _targetFromItem;
/**
* Creates the expr.
*/
public ManyToOneJoinExpr(LinkColumns link,
FromItem source,
FromItem target)
{
_linkColumns = link;
_sourceFromItem = source;
_targetFromItem = target;
// commented out: jpa/10c9
// if (source == null || target == null)
if (target == null)
throw new NullPointerException();
}
/**
* Returns true for a boolean expression.
*/
public boolean isBoolean()
{
return true;
}
/**
* Returns true for a many-to-many expression.
*/
public boolean isManyToMany()
{
if (_sourceFromItem == null)
return false;
return _sourceFromItem.getJoinExpr() instanceof OneToManyJoinExpr;
}
/**
* 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 (_targetFromItem.getJoinExpr() == null ||
_targetFromItem.getJoinExpr().equals(this)) {
_targetFromItem.setJoinExpr(this);
return true;
}
else if (_sourceFromItem.getJoinExpr() == null) {
_sourceFromItem.setJoinExpr(new OneToManyJoinExpr(_linkColumns,
_sourceFromItem,
_targetFromItem));
return true;
}
else
return false;
}
/**
* Returns the target join clause.
*/
public FromItem getJoinTarget()
{
return _targetFromItem;
}
/**
* Returns the target join clause.
*/
public FromItem getJoinParent()
{
return _sourceFromItem;
}
/**
* Returns true if the expression uses the from item.
*/
public boolean usesFrom(FromItem from, int type, boolean isNot)
{
return from == _targetFromItem || from == _sourceFromItem;
}
/**
* Returns true if the expression uses the from item.
*/
@Override
public boolean exists(FromItem from)
{
return false;
}
/**
* Returns the id expr with the joined expression.
*/
public AmberExpr replace(KeyColumnExpr id)
{
PathExpr parent = (PathExpr) id.getParent();
if (parent.getChildFromItem() != _targetFromItem)
return id;
ForeignColumn sourceColumn = _linkColumns.getSourceColumn(id.getColumn());
if (sourceColumn == null)
throw new IllegalStateException(id.getColumn().getName());
return new ColumnExpr(_sourceFromItem.getIdExpr(), sourceColumn);
}
/**
* Returns the id expr with the joined expression.
*/
public AmberExpr replace(IdExpr id)
{
return id;
}
/**
* Generates the where expression.
*/
public void generateWhere(CharBuffer cb)
{
String sourceName = null;
// jpa/10c9
if (_sourceFromItem != null)
sourceName = _sourceFromItem.getName();
String targetName = _targetFromItem.getName();
cb.append(_linkColumns.generateWhere(sourceName,
targetName));
}
/**
* Generates the (update) where expression.
*/
public void generateUpdateWhere(CharBuffer cb)
{
generateWhere(cb);
}
/**
* Generates the having expression.
*/
public void generateHaving(CharBuffer cb)
{
generateWhere(cb);
}
/**
* Generates the where expression.
*/
public void generateJoin(CharBuffer cb)
{
cb.append(_linkColumns.generateJoin(_sourceFromItem.getName(),
_targetFromItem.getName()));
}
/**
* Test for equality.
*/
public boolean equals(Object o)
{
if (! (o instanceof ManyToOneJoinExpr))
return false;
ManyToOneJoinExpr joinExpr = (ManyToOneJoinExpr) o;
return (_linkColumns.equals(joinExpr._linkColumns) &&
_sourceFromItem.equals(joinExpr._sourceFromItem) &&
_targetFromItem.equals(joinExpr._targetFromItem));
}
public String toString()
{
return ("ManyToOneJoinExpr[" + _linkColumns + "," +
_sourceFromItem + "," + _targetFromItem + "]");
}
}