/*******************************************************************************
* Copyright (c) 2006, 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.parser;
import java.util.Collection;
import java.util.List;
import org.eclipse.persistence.jpa.jpql.ExpressionTools;
import org.eclipse.persistence.jpa.jpql.WordParser;
/**
* A result variable may be used to name a select item in the query result.
*
* <div><b>BNF:</b> <code>select_item ::= select_expression [[AS] result_variable]</code><p></div>
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
public final class ResultVariable extends AbstractExpression {
/**
* The actual <b>AS</b> identifier found in the string representation of the JPQL query.
*/
private String asIdentifier;
/**
* Determines whether a whitespace was parsed after the identifier <b>AS</b>.
*/
private boolean hasSpaceAfterAs;
/**
* The {@link Expression} used
*/
private AbstractExpression resultVariable;
/**
* The {@link Expression} representing the select expression.
*/
private AbstractExpression selectExpression;
/**
* Creates a new <code>ResultVariable</code>.
*
* @param parent The parent of this expression
* @param selectExpression The expression that represents the select expression, which will have
* a variable assigned to it
*/
public ResultVariable(AbstractExpression parent, AbstractExpression selectExpression) {
super(parent);
if (selectExpression != null) {
this.selectExpression = selectExpression;
this.selectExpression.setParent(this);
}
}
/**
* {@inheritDoc}
*/
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
*/
public void acceptChildren(ExpressionVisitor visitor) {
getSelectExpression().accept(visitor);
getResultVariable().accept(visitor);
}
/**
* {@inheritDoc}
*/
@Override
protected void addChildrenTo(Collection<Expression> children) {
children.add(getSelectExpression());
children.add(getResultVariable());
}
/**
* {@inheritDoc}
*/
@Override
protected void addOrderedChildrenTo(List<Expression> children) {
// Select expression
if (selectExpression != null) {
children.add(selectExpression);
children.add(buildStringExpression(SPACE));
}
// 'AS'
if (asIdentifier != null) {
children.add(buildStringExpression(AS));
}
if (hasSpaceAfterAs) {
children.add(buildStringExpression(SPACE));
}
// Result variable
if (resultVariable != null) {
children.add(resultVariable);
}
}
/**
* {@inheritDoc}
*/
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((selectExpression != null) && selectExpression.isAncestor(expression)) {
return getQueryBNF(SelectExpressionBNF.ID);
}
if ((resultVariable != null) && resultVariable.isAncestor(expression)) {
return getQueryBNF(IdentificationVariableBNF.ID);
}
return super.findQueryBNF(expression);
}
/**
* Returns the actual <b>AS</b> found in the string representation of the JPQL query, which has
* the actual case that was used.
*
* @return The <b>AS</b> identifier that was actually parsed, or an empty string if it was not parsed
*/
public String getActualAsIdentifier() {
return (asIdentifier != null) ? asIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* {@inheritDoc}
*/
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(ResultVariableBNF.ID);
}
/**
* Returns the {@link Expression} representing the result variable.
*
* @return The expression for the result variable
*/
public Expression getResultVariable() {
if (resultVariable == null) {
resultVariable = buildNullExpression();
}
return resultVariable;
}
/**
* Returns the {@link Expression} representing the select expression.
*
* @return The expression for the select expression
*/
public Expression getSelectExpression() {
if (selectExpression == null) {
selectExpression = buildNullExpression();
}
return selectExpression;
}
/**
* Determines whether the identifier <b>AS</b> was parsed or not.
*
* @return <code>true</code> if the identifier <b>AS</b> was parsed; <code>false</code> otherwise
*/
public boolean hasAs() {
return asIdentifier != null;
}
/**
* Determines whether the result variable was parsed.
*
* @return <code>true</code> if the result variable was parsed; <code>false</code> otherwise
*/
public boolean hasResultVariable() {
return resultVariable != null &&
!resultVariable.isNull();
}
/**
* Determines whether a select expression was defined for this result variable.
*
* @return <code>true</code> if the select expression was parsed; <code>false</code> if the
* result variable was parsed without one
*/
public boolean hasSelectExpression() {
return selectExpression != null &&
!selectExpression.isNull();
}
/**
* Determines whether a whitespace was parsed after the identifier <b>AS</b>.
*
* @return <code>true</code> if there was a whitespace after <b>AS</b>; <code>false</code> otherwise
*/
public boolean hasSpaceAfterAs() {
return hasSpaceAfterAs;
}
/**
* {@inheritDoc}
*/
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
// Parse 'AS'
if (wordParser.startsWithIdentifier(AS)) {
asIdentifier = wordParser.moveForward(2);
hasSpaceAfterAs = wordParser.skipLeadingWhitespace() > 0;
}
// Parse the result variable
if (tolerant) {
resultVariable = parse(wordParser, IdentificationVariableBNF.ID, tolerant);
}
else {
resultVariable = new IdentificationVariable(this, wordParser.word());
resultVariable.parse(wordParser, tolerant);
}
}
/**
* {@inheritDoc}
*/
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
// Select expression
if (selectExpression != null) {
selectExpression.toParsedText(writer, actual);
if ((writer.length() > 0) && (writer.charAt(writer.length() - 1) != SPACE)) {
writer.append(SPACE);
}
}
// 'AS'
if (asIdentifier != null) {
writer.append(actual ? asIdentifier : AS);
}
if (hasSpaceAfterAs) {
writer.append(SPACE);
}
// Result variable
if (resultVariable != null) {
resultVariable.toParsedText(writer, actual);
}
}
}