org.eclipse.persistence.jpa.jpql.parser.ResultVariable Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of eclipselink Show documentation
Show all versions of eclipselink Show documentation
EclipseLink build based upon Git transaction f2b9fc5
/*
* Copyright (c) 2006, 2020 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 v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// 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.
*
* BNF: select_item ::= select_expression [[AS] result_variable]
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
public final class ResultVariable extends AbstractExpression {
/**
* The actual AS identifier found in the string representation of the JPQL query.
*/
private String asIdentifier;
/**
* Determines whether a whitespace was parsed after the identifier AS.
*/
private boolean hasSpaceAfterAs;
/**
* The {@link Expression} used
*/
private AbstractExpression resultVariable;
/**
* The {@link Expression} representing the select expression.
*/
private AbstractExpression selectExpression;
/**
* Creates a new ResultVariable.
*
* @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);
}
}
@Override
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
@Override
public void acceptChildren(ExpressionVisitor visitor) {
getSelectExpression().accept(visitor);
getResultVariable().accept(visitor);
}
@Override
protected void addChildrenTo(Collection children) {
children.add(getSelectExpression());
children.add(getResultVariable());
}
@Override
protected void addOrderedChildrenTo(List 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);
}
}
@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 AS found in the string representation of the JPQL query, which has
* the actual case that was used.
*
* @return The AS identifier that was actually parsed, or an empty string if it was not parsed
*/
public String getActualAsIdentifier() {
return (asIdentifier != null) ? asIdentifier : ExpressionTools.EMPTY_STRING;
}
@Override
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 AS was parsed or not.
*
* @return true if the identifier AS was parsed; false otherwise
*/
public boolean hasAs() {
return asIdentifier != null;
}
/**
* Determines whether the result variable was parsed.
*
* @return true if the result variable was parsed; false otherwise
*/
public boolean hasResultVariable() {
return resultVariable != null &&
!resultVariable.isNull();
}
/**
* Determines whether a select expression was defined for this result variable.
*
* @return true if the select expression was parsed; false 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 AS.
*
* @return true if there was a whitespace after AS; false otherwise
*/
public boolean hasSpaceAfterAs() {
return hasSpaceAfterAs;
}
@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);
}
}
@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);
}
}
}