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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.cayenne.access.jdbc;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.apache.cayenne.ejbql.EJBQLBaseVisitor;
import org.apache.cayenne.ejbql.EJBQLException;
import org.apache.cayenne.ejbql.EJBQLExpression;
import org.apache.cayenne.ejbql.parser.EJBQLIdentificationVariable;
import org.apache.cayenne.ejbql.parser.EJBQLIdentifier;
import org.apache.cayenne.ejbql.parser.EJBQLInnerJoin;
import org.apache.cayenne.ejbql.parser.EJBQLPath;
import org.apache.cayenne.map.DbEntity;
import org.apache.cayenne.map.DbJoin;
import org.apache.cayenne.map.DbRelationship;
import org.apache.cayenne.map.ObjAttribute;
import org.apache.cayenne.map.ObjEntity;
import org.apache.cayenne.map.ObjRelationship;
import org.apache.cayenne.reflect.ClassDescriptor;
/**
* A translator that walks the relationship/attribute path, appending joins to the query.
*
* @since 3.0
* @author Andrus Adamchik
*/
abstract class EJBQLPathTranslator extends EJBQLBaseVisitor {
private EJBQLTranslationContext context;
protected ObjEntity currentEntity;
private String lastPathComponent;
protected String lastAlias;
protected String idPath;
protected String joinMarker;
private String fullPath;
private EJBQLFromTranslator joinAppender;
EJBQLPathTranslator(EJBQLTranslationContext context) {
super(true);
this.context = context;
}
protected abstract void appendMultiColumnPath(EJBQLMultiColumnOperand operand);
public boolean visitPath(EJBQLPath expression, int finishedChildIndex) {
if (finishedChildIndex > 0) {
if (finishedChildIndex + 1 < expression.getChildrenCount()) {
processIntermediatePathComponent();
}
else {
processLastPathComponent();
}
}
return true;
}
public boolean visitIdentifier(EJBQLExpression expression) {
ClassDescriptor descriptor = context.getCompiledExpression().getEntityDescriptor(
expression.getText());
if (descriptor == null) {
throw new EJBQLException("Invalid identification variable: "
+ expression.getText());
}
this.currentEntity = descriptor.getEntity();
this.idPath = expression.getText();
this.joinMarker = EJBQLFromTranslator.makeJoinTailMarker(idPath);
this.fullPath = idPath;
return true;
}
public boolean visitIdentificationVariable(EJBQLExpression expression) {
// TODO: andrus 6/11/2007 - if the path ends with relationship, the last join will
// get lost...
if (lastPathComponent != null) {
resolveJoin();
}
this.lastPathComponent = expression.getText();
return true;
}
private EJBQLFromTranslator getJoinAppender() {
if (joinAppender == null) {
joinAppender = new EJBQLFromTranslator(context);
}
return joinAppender;
}
private void resolveJoin() {
String newPath = idPath + '.' + lastPathComponent;
String oldPath = context.registerReusableJoin(idPath, lastPathComponent, newPath);
this.fullPath = fullPath + '.' + lastPathComponent;
if (oldPath != null) {
this.idPath = oldPath;
this.lastAlias = context.getTableAlias(oldPath, currentEntity
.getDbEntityName());
}
else {
// register join
EJBQLIdentifier id = new EJBQLIdentifier(-1);
id.setText(idPath);
EJBQLIdentificationVariable idVar = new EJBQLIdentificationVariable(-1);
idVar.setText(lastPathComponent);
EJBQLPath path = new EJBQLPath(-1);
path.jjtAddChild(id, 0);
path.jjtAddChild(idVar, 1);
EJBQLIdentifier joinId = new EJBQLIdentifier(-1);
joinId.setText(fullPath);
EJBQLInnerJoin join = new EJBQLInnerJoin(-1);
join.jjtAddChild(path, 0);
join.jjtAddChild(joinId, 1);
context.switchToMarker(joinMarker);
getJoinAppender().visitInnerJoin(join);
context.switchToMainBuffer();
this.idPath = newPath;
this.lastAlias = context.getTableAlias(fullPath, currentEntity
.getDbEntityName());
}
}
private void processIntermediatePathComponent() {
ObjRelationship relationship = (ObjRelationship) currentEntity
.getRelationship(lastPathComponent);
if (relationship == null) {
throw new EJBQLException("Unknown relationship '"
+ lastPathComponent
+ "' for entity '"
+ currentEntity.getName()
+ "'");
}
this.currentEntity = (ObjEntity) relationship.getTargetEntity();
}
private void processLastPathComponent() {
ObjAttribute attribute = (ObjAttribute) currentEntity
.getAttribute(lastPathComponent);
if (attribute != null) {
processTerminatingAttribute(attribute);
return;
}
ObjRelationship relationship = (ObjRelationship) currentEntity
.getRelationship(lastPathComponent);
if (relationship != null) {
processTerminatingRelationship(relationship);
return;
}
throw new IllegalStateException("Invalid path component: " + lastPathComponent);
}
protected void processTerminatingAttribute(ObjAttribute attribute) {
DbEntity table = currentEntity.getDbEntity();
String alias = this.lastAlias != null ? lastAlias : context.getTableAlias(
idPath,
table.getFullyQualifiedName());
context.append(' ').append(alias).append('.').append(
attribute.getDbAttributeName());
}
private void processTerminatingRelationship(ObjRelationship relationship) {
// check whether we need a join
if (relationship.isSourceIndependentFromTargetChange()) {
// TODO: andrus, 6/13/2007 - implement
}
else {
// match FK against the target object
// TODO: andrus, 6/21/2007 - flattened support
DbRelationship dbRelationship = (DbRelationship) relationship
.getDbRelationships()
.get(0);
DbEntity table = (DbEntity) dbRelationship.getSourceEntity();
String alias = this.lastAlias != null ? lastAlias : context.getTableAlias(
idPath,
table.getFullyQualifiedName());
List joins = dbRelationship.getJoins();
if (joins.size() == 1) {
DbJoin join = (DbJoin) joins.get(0);
context
.append(' ')
.append(alias)
.append('.')
.append(join.getSourceName());
}
else {
Map multiColumnMatch = new HashMap(joins.size() + 2);
Iterator it = joins.iterator();
while (it.hasNext()) {
DbJoin join = (DbJoin) it.next();
String column = alias + "." + join.getSourceName();
multiColumnMatch.put(join.getTargetName(), column);
}
appendMultiColumnPath(EJBQLMultiColumnOperand.getPathOperand(
context,
multiColumnMatch));
}
}
}
}