/*******************************************************************************
* Copyright (c) 2011, 2015 Oracle and/or its affiliates. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation
*
******************************************************************************/
package org.eclipse.persistence.internal.jpa.jpql;
import java.util.Collections;
import java.util.List;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.jpa.jpql.ExpressionTools;
import org.eclipse.persistence.jpa.jpql.JPQLQueryDeclaration;
import org.eclipse.persistence.jpa.jpql.parser.AbstractExpression;
import org.eclipse.persistence.jpa.jpql.parser.Expression;
import org.eclipse.persistence.jpa.jpql.parser.IdentificationVariable;
import org.eclipse.persistence.jpa.jpql.parser.Join;
import org.eclipse.persistence.mappings.DatabaseMapping;
/**
* A <code>Declaration</code> is the corresponding representation of a single declaration defined in
* the <code><b>FROM</b></code> clause of a query.
*
* @version 2.5
* @since 2.4
* @author Pascal Filion
*/
abstract class Declaration implements JPQLQueryDeclaration {
/**
* TODO.
*/
Expression baseExpression;
/**
* The declaration expression, which is either an {@link org.eclipse.persistence.jpa.jpql.parser.
* IdentificationVariableDeclaration IdentificationVariableDeclaration} or a {@link
* org.eclipse.persistence.jpa.jpql.parser.CollectionMemberDeclaration CollectionMemberDeclaration}
* when part of a <b>FROM</b> clause, otherwise it's either the {@link org.eclipse.persistence.
* jpa.jpql.parser.DeleteClause DeleteClause} or the {@link org.eclipse.persistence.jpa.jpql.
* parser.UpdateClause UpdateClause}.
*/
Expression declarationExpression;
/**
* The cached {@link ClassDescriptor} that represents this {@link Declaration}'s "root" path.
*/
private ClassDescriptor descriptor;
/**
* The {@link IdentificationVariable} used to declare a "root" object.
*/
IdentificationVariable identificationVariable;
/**
* The cached {@link DatabaseMapping} if this {@link Declaration}'s "root" path points to a
* mapping, otherwise it will be <code>null</code>.
*/
private DatabaseMapping mapping;
/**
* The {@link JPQLQueryContext} is used to query information about the application metadata and
* cached information.
*/
final JPQLQueryContext queryContext;
/**
* The {@link org.eclipse.persistence.expressions.Expression Expression} representing the
* information of this {@link Declaration}.
*/
private org.eclipse.persistence.expressions.Expression queryExpression;
/**
* The "root" object for objects which may not be reachable by navigation, it is either the
* abstract schema name (entity name), a derived path expression (which is only defined in a
* subquery) or <code>null</code> if this {@link Declaration} is a collection member declaration.
*/
String rootPath;
/**
* Creates a new <code>Declaration</code>.
*
* @param queryContext The context used to query information about the application metadata and
* cached information
*/
Declaration(JPQLQueryContext queryContext) {
super();
this.queryContext = queryContext;
}
/**
* Creates the Expression {@link Expression} for this {@link Declaration}.
*
* @return A new {@link org.eclipse.persistence.expressions.Expression Expression}
*/
abstract org.eclipse.persistence.expressions.Expression buildQueryExpression();
/**
* {@inheritDoc}
*/
@Override
public Expression getBaseExpression() {
return baseExpression;
}
/**
* {@inheritDoc}
*/
@Override
public Expression getDeclarationExpression() {
return declarationExpression;
}
/**
* Returns the {@link ClassDescriptor} that represents this {@link Declaration}'s "root" path.
*
* @return The descriptor of the "root" path
*/
final ClassDescriptor getDescriptor() {
if (descriptor == null) {
descriptor = resolveDescriptor();
}
return descriptor;
}
/**
* {@inheritDoc}
*/
@Override
public List<Join> getJoins() {
return Collections.emptyList();
}
/**
* Returns the {@link DatabaseMapping} that this {@link Declaration} represents, which may be
* <code>null</code> in the case it does not represent one.
*
* @return Either the {@link DatabaseMapping} of the "root" path, or <code>null</code> if the
* "root" path is not a mapping
*/
final DatabaseMapping getMapping() {
if (mapping == null) {
mapping = resolveMapping();
}
return mapping;
}
/**
* Returns the Expression {@link Expression} for this {@link Declaration}.
*
* @return The {@link org.eclipse.persistence.expressions.Expression Expression} representing the
* information of this {@link Declaration}
*/
final org.eclipse.persistence.expressions.Expression getQueryExpression() {
if (queryExpression == null) {
// First create the Expression
queryExpression = buildQueryExpression();
// Cache the base expression with its identification variable as well
queryContext.addQueryExpressionImp(getVariableName(), queryExpression);
}
return queryExpression;
}
/**
* {@inheritDoc}
*/
@Override
public final String getVariableName() {
if (identificationVariable == null) {
return ExpressionTools.EMPTY_STRING;
}
return identificationVariable.getVariableName();
}
/**
* {@inheritDoc}
*/
@Override
public boolean hasJoins() {
return false;
}
/**
* Resolves this {@link Declaration} and returns the associated {@link ClassDescriptor}. For a
* {@link RangeVariableDeclaration}, this will return the actual descriptor for the entity. For
* a mapping, this will return the reference descriptor.
*
* @return The descriptor associated with this declaration
*/
abstract ClassDescriptor resolveDescriptor();
/**
* Resolves this {@link Declaration} and returns the associated {@link DatabaseMapping} if this
* represents a path expression. In the case of a {@link RangeVariableDeclaration}, this will
* return <code>null</code>.
*
* @return The mapping associated with this declaration
*/
abstract DatabaseMapping resolveMapping();
/**
* {@inheritDoc}
*/
@Override
public String toString() {
if (declarationExpression != null) {
return declarationExpression.toParsedText();
}
StringBuilder sb = new StringBuilder();
sb.append(rootPath);
if (identificationVariable != null) {
sb.append(AbstractExpression.SPACE);
sb.append(identificationVariable.getText());
}
return sb.toString();
}
}