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/*
* Copyright (c) 2006, 2021 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;
/**
* BNF: general_case_expression ::= CASE when_clause {when_clause}* ELSE scalar_expression END
* or
* BNF: simple_case_expression ::= CASE case_operand simple_when_clause {simple_when_clause}* ELSE scalar_expression END
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
public final class CaseExpression extends AbstractExpression {
/**
* The actual CASE identifier found in the string representation of the JPQL query.
*/
private String caseIdentifier;
/**
* The {@link Expression} representing the case operand.
*/
private AbstractExpression caseOperand;
/**
* The {@link Expression} representing the ELSE expression.
*/
private AbstractExpression elseExpression;
/**
* The actual ELSE identifier found in the string representation of the JPQL query.
*/
private String elseIdentifier;
/**
* The actual END identifier found in the string representation of the JPQL query.
*/
private String endIdentifier;
/**
* Determines whether a whitespace was parsed after CASE.
*/
private boolean hasSpaceAfterCase;
/**
* Determines whether a whitespace was parsed after the case operand.
*/
private boolean hasSpaceAfterCaseOperand;
/**
* Determines whether a whitespace was parsed after ELSE.
*/
private boolean hasSpaceAfterElse;
/**
* Determines whether a whitespace was parsed after the BETWEEN expression.
*/
private boolean hasSpaceAfterElseExpression;
/**
* Determines whether a whitespace was parsed after WHEN clause.
*/
private boolean hasSpaceAfterWhenClauses;
/**
* Used to determine how to check if the parsing is complete.
*/
private ParsingType parsingType;
/**
* The {@link Expression} representing the WHEN clauses.
*/
private AbstractExpression whenClauses;
/**
* Creates a new CaseExpression.
*
* @param parent The parent of this expression
*/
public CaseExpression(AbstractExpression parent) {
super(parent, CASE);
}
@Override
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
@Override
public void acceptChildren(ExpressionVisitor visitor) {
getCaseOperand().accept(visitor);
getWhenClauses().accept(visitor);
getElseExpression().accept(visitor);
}
@Override
protected void addChildrenTo(Collection children) {
children.add(getCaseOperand());
children.add(getWhenClauses());
children.add(getElseExpression());
}
@Override
protected void addOrderedChildrenTo(List children) {
// 'CASE'
children.add(buildStringExpression(CASE));
if (hasSpaceAfterCase) {
children.add(buildStringExpression(SPACE));
}
// Case operand
if (caseOperand != null) {
children.add(caseOperand);
}
if (hasSpaceAfterCaseOperand) {
children.add(buildStringExpression(SPACE));
}
// WHEN clauses
if (whenClauses != null) {
children.add(whenClauses);
}
if (hasSpaceAfterWhenClauses) {
children.add(buildStringExpression(SPACE));
}
// 'ELSE'
if (elseIdentifier != null) {
children.add(buildStringExpression(ELSE));
}
if (hasSpaceAfterElse) {
children.add(buildStringExpression(SPACE));
}
// Else expression
if (elseExpression != null) {
children.add(elseExpression);
}
if (hasSpaceAfterElseExpression) {
children.add(buildStringExpression(SPACE));
}
// 'END'
if (endIdentifier != null) {
children.add(buildStringExpression(END));
}
}
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((caseOperand != null) && caseOperand.isAncestor(expression)) {
return getQueryBNF(CaseOperandBNF.ID);
}
if ((whenClauses != null) && whenClauses.isAncestor(expression)) {
return getQueryBNF(WhenClauseBNF.ID);
}
if ((elseExpression != null) && elseExpression.isAncestor(expression)) {
return getQueryBNF(ElseExpressionBNF.ID);
}
return super.findQueryBNF(expression);
}
/**
* Returns the actual CASE identifier found in the string representation of the JPQL
* query, which has the actual case that was used.
*
* @return The CASE identifier that was actually parsed
*/
public String getActualCaseIdentifier() {
return caseIdentifier;
}
/**
* Returns the actual ELSE identifier found in the string representation of the JPQL
* query, which has the actual case that was used.
*
* @return The ELSE identifier that was actually parsed, or an empty string if it was not
* parsed
*/
public String getActualElseIdentifier() {
return (elseIdentifier != null) ? elseIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* Returns the actual END identifier found in the string representation of the JPQL query,
* which has the actual case that was used.
*
* @return The END identifier that was actually parsed, or an empty string if it was not
* parsed
*/
public String getActualEndIdentifier() {
return (endIdentifier != null) ? endIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* Returns the {@link Expression} that represents the CASE operand.
*
* @return The expression that was parsed representing the CASE operand
*/
public Expression getCaseOperand() {
if (caseOperand == null) {
caseOperand = buildNullExpression();
}
return caseOperand;
}
/**
* Returns the {@link Expression} that represents the ELSE operand.
*
* @return The expression that was parsed representing the ELSE operand
*/
public AbstractExpression getElseExpression() {
if (elseExpression == null) {
elseExpression = buildNullExpression();
}
return elseExpression;
}
@Override
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(GeneralCaseExpressionBNF.ID);
}
/**
* Returns the {@link Expression} that represents the WHEN clauses.
*
* @return The expression that was parsed representing the WHEN clauses
*/
public AbstractExpression getWhenClauses() {
if (whenClauses == null) {
whenClauses = buildNullExpression();
}
return whenClauses;
}
/**
* Determines whether the CASE operand was parsed.
*
* @return true if the CASE operand was parsed; false otherwise
*/
public boolean hasCaseOperand() {
return caseOperand != null &&
!caseOperand.isNull();
}
/**
* Determines whether the identifier ELSE was parsed.
*
* @return true if the identifier ELSE was parsed; false
* otherwise
*/
public boolean hasElse() {
return elseIdentifier != null;
}
/**
* Determines whether the ELSE expression was parsed.
*
* @return true if the ELSE expression was parsed; false
* otherwise
*/
public boolean hasElseExpression() {
return elseExpression != null &&
!elseExpression.isNull();
}
/**
* Determines whether the identifier END was parsed.
*
* @return true if the identifier END was parsed; false otherwise
*/
public boolean hasEnd() {
return endIdentifier != null;
}
/**
* Determines whether a whitespace was parsed after CASE.
*
* @return true if there was a whitespace after CASE; false
* otherwise
*/
public boolean hasSpaceAfterCase() {
return hasSpaceAfterCase;
}
/**
* Determines whether a whitespace was parsed after the case operand.
*
* @return true if there was a whitespace after the case operand; false
* otherwise
*/
public boolean hasSpaceAfterCaseOperand() {
return hasSpaceAfterCaseOperand;
}
/**
* Determines whether a whitespace was parsed after ELSE.
*
* @return true if there was a whitespace after ELSE; false
* otherwise
*/
public boolean hasSpaceAfterElse() {
return hasSpaceAfterElse;
}
/**
* Determines whether a whitespace was parsed after the else expression.
*
* @return true if there was a whitespace after the else expression;
* false otherwise
*/
public boolean hasSpaceAfterElseExpression() {
return hasSpaceAfterElseExpression;
}
/**
* Determines whether a whitespace was parsed after the WHEN clause.
*
* @return true if there was a whitespace after the WHEN
* clause; false otherwise
*/
public boolean hasSpaceAfterWhenClauses() {
return hasSpaceAfterWhenClauses;
}
/**
* Determines whether the WHEN clauses were parsed.
*
* @return true if the WHEN clauses were parsed;
* false otherwise
*/
public boolean hasWhenClauses() {
return whenClauses != null &&
!whenClauses.isNull();
}
@Override
protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression) {
// 'CASE'
if (parsingType == ParsingType.CASE) {
return word.equalsIgnoreCase(WHEN) ||
word.equalsIgnoreCase(ELSE) ||
word.equalsIgnoreCase(END) ||
super.isParsingComplete(wordParser, word, expression);
}
// 'WHEN'
if (parsingType == ParsingType.WHEN) {
return word.equalsIgnoreCase(ELSE) ||
word.equalsIgnoreCase(END) ||
super.isParsingComplete(wordParser, word, expression);
}
// 'ELSE'
return word.equalsIgnoreCase(END) ||
super.isParsingComplete(wordParser, word, expression);
}
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
// Parse 'CASE'
caseIdentifier = wordParser.moveForward(CASE);
hasSpaceAfterCase = wordParser.skipLeadingWhitespace() > 0;
// Parse case operand
parsingType = ParsingType.CASE;
if (!wordParser.startsWithIdentifier(WHEN)) {
caseOperand = parse(wordParser, CaseOperandBNF.ID, tolerant);
hasSpaceAfterCaseOperand = wordParser.skipLeadingWhitespace() > 0;
}
// Parse the WHEN clauses
parsingType = ParsingType.WHEN;
whenClauses = parse(wordParser, WhenClauseBNF.ID, tolerant);
hasSpaceAfterWhenClauses = wordParser.skipLeadingWhitespace() > 0;
// Parse 'ELSE'
if (!tolerant || wordParser.startsWithIdentifier(ELSE)) {
elseIdentifier = wordParser.moveForward(ELSE);
hasSpaceAfterElse = wordParser.skipLeadingWhitespace() > 0;
}
// Parse the ELSE expression
parsingType = ParsingType.ELSE;
elseExpression = parse(wordParser, ElseExpressionBNF.ID, tolerant);
hasSpaceAfterElseExpression = wordParser.skipLeadingWhitespace() > 0;
// Parse 'END'
if (!tolerant || wordParser.startsWithIdentifier(END)) {
endIdentifier = wordParser.moveForward(END);
}
}
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
// 'CASE'
writer.append(actual ? caseIdentifier : CASE);
if (hasSpaceAfterCase) {
writer.append(SPACE);
}
// Case Operand
if (caseOperand != null) {
caseOperand.toParsedText(writer, actual);
}
if (hasSpaceAfterCaseOperand) {
writer.append(SPACE);
}
// When clauses
if (whenClauses != null) {
whenClauses.toParsedText(writer, actual);
}
if (hasSpaceAfterWhenClauses) {
writer.append(SPACE);
}
// 'ELSE'
if (elseIdentifier != null) {
writer.append(actual ? elseIdentifier : ELSE);
}
if (hasSpaceAfterElse) {
writer.append(SPACE);
}
// Else expression
if (elseExpression != null) {
elseExpression.toParsedText(writer, actual);
}
if (hasSpaceAfterElseExpression) {
writer.append(SPACE);
}
// 'END'
if (endIdentifier != null) {
writer.append(actual ? endIdentifier : END);
}
}
/**
* A enumeration used to determine how {@link CaseExpression#isParsingComplete(WordParser, String, Expression)}
* should behaves.
*/
private enum ParsingType {
CASE,
ELSE,
WHEN
}
}