/*******************************************************************************
* 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 Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public 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.jpa.jpql.tools.model.query;
import java.io.IOException;
import java.util.List;
import org.eclipse.persistence.jpa.jpql.parser.SimpleSelectClause;
import org.eclipse.persistence.jpa.jpql.parser.SimpleSelectExpressionBNF;
import org.eclipse.persistence.jpa.jpql.tools.model.ISimpleSelectExpressionStateObjectBuilder;
import static org.eclipse.persistence.jpa.jpql.parser.AbstractExpression.*;
import static org.eclipse.persistence.jpa.jpql.parser.Expression.*;
/**
* The <b>SELECT</b> statement queries data from entities. This version simply does not handle
* <b>OBJECT</b> and <b>NEW</b> identifiers. It is used from within another expression.
*
* <div><b>BNF:</b> <code>simple_select_clause ::= SELECT [DISTINCT] simple_select_expression</code><p></div>
*
* @see SimpleSelectClause
*
* @version 2.4
* @since 2.4
* @author Pascal Filion
*/
@SuppressWarnings({"nls", "unused"}) // unused used for the import statement: see bug 330740
public class SimpleSelectClauseStateObject extends AbstractSelectClauseStateObject {
/**
* The builder is cached during the creation of the select expression.
*/
private ISimpleSelectExpressionStateObjectBuilder builder;
/**
* The state object representing the single select expression.
*/
private StateObject stateObject;
/**
* Notifies the select expression property has changed.
*/
public static final String SELECT_ITEM_PROPERTY = "stateObject";
/**
* Creates a new <code>SubQuerySelectClauseStateObject</code>.
*
* @param parent The parent of this state object, which cannot be <code>null</code>
* @exception NullPointerException The given parent cannot be <code>null</code>
*/
public SimpleSelectClauseStateObject(SimpleSelectStatementStateObject parent) {
super(parent);
}
/**
* {@inheritDoc}
*/
public void accept(StateObjectVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
*/
@Override
protected void addChildren(List<StateObject> children) {
super.addChildren(children);
if (stateObject != null) {
children.add(stateObject);
}
}
/**
* Creates and returns a new {@link ISimpleSelectExpressionStateObjectBuilder} that can be used
* to programmatically create a single select expression and once the expression is complete,
* {@link ISimpleSelectExpressionStateObjectBuilder#commit()} will push the {@link StateObject}
* representation of that expression as this clause's select expression.
*
* @return A new builder that can be used to quickly create a select expression
*/
public ISimpleSelectExpressionStateObjectBuilder getBuilder() {
if (builder == null) {
builder = getQueryBuilder().buildStateObjectBuilder(this);
}
return builder;
}
/**
* {@inheritDoc}
*/
@Override
public SimpleSelectClause getExpression() {
return (SimpleSelectClause) super.getExpression();
}
/**
* {@inheritDoc}
*/
@Override
public SimpleFromClauseStateObject getFromClause() {
return (SimpleFromClauseStateObject) super.getFromClause();
}
/**
* {@inheritDoc}
*/
@Override
public SimpleSelectStatementStateObject getParent() {
return (SimpleSelectStatementStateObject) super.getParent();
}
/**
* Returns
*
* @return
*/
public StateObject getSelectItem() {
return stateObject;
}
/**
* {@inheritDoc}
*/
@Override
public boolean hasSelectItem() {
return stateObject != null;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isEquivalent(StateObject stateObject) {
if (super.isEquivalent(stateObject)) {
SimpleSelectClauseStateObject select = (SimpleSelectClauseStateObject) stateObject;
return areEquivalent(this.stateObject, select.stateObject);
}
return false;
}
/**
* {@inheritDoc}
*/
@Override
public void parse(String jpqlFragment) {
StateObject stateObject = buildStateObject(jpqlFragment, SimpleSelectExpressionBNF.ID);
setSelectItem(stateObject);
}
/**
* Keeps a reference of the {@link SimpleSelectClause parsed object} object, which should only be
* done when this object is instantiated during the conversion of a parsed JPQL query into
* {@link StateObject StateObjects}.
*
* @param expression The {@link SimpleSelectClause parsed object} representing a subquery
* <code><b>SELECT</b></code> clause
*/
public void setExpression(SimpleSelectClause expression) {
super.setExpression(expression);
}
/**
* Sets the given {@link StateObject} as this clause's select item.
*
* @param stateObject The {@link StateObject} representing the single select item
*/
public void setSelectItem(StateObject stateObject) {
StateObject oldStateObject = this.stateObject;
this.stateObject = parent(stateObject);
firePropertyChanged(SELECT_ITEM_PROPERTY, oldStateObject, stateObject);
}
/**
* {@inheritDoc}
*/
@Override
protected void toTextInternal(Appendable writer) throws IOException {
// 'SELECT'
writer.append(SELECT);
// 'DISTINCT'
if (hasDistinct()) {
writer.append(SPACE);
writer.append(DISTINCT);
}
// Select expression
if (stateObject != null) {
writer.append(SPACE);
stateObject.toString(writer);
}
}
}