| /* |
| * 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; |
| |
| /** |
| * A null comparison tests whether or not the single-valued path expression or input parameter is a |
| * <b>NULL</b> value. |
| * |
| * <div><b>BNF:</b> <code>null_comparison_expression ::= {single_valued_path_expression | input_parameter} IS [NOT] NULL</code><p></p></div> |
| * |
| * @version 2.5 |
| * @since 2.3 |
| * @author Pascal Filion |
| */ |
| public final class NullComparisonExpression extends AbstractExpression { |
| |
| /** |
| * The expression tested for being <code>null</code> or not. |
| */ |
| private AbstractExpression expression; |
| |
| /** |
| * The actual <b>IS</b> identifier found in the string representation of the JPQL query. |
| */ |
| private String isIdentifier; |
| |
| /** |
| * The actual <b>IS</b> identifier found in the string representation of the JPQL query. |
| */ |
| private String notIdentifier; |
| |
| /** |
| * The actual <b>NULL</b> identifier found in the string representation of the JPQL query. |
| */ |
| private String nullIdentifier; |
| |
| /** |
| * Creates a new <code>NullComparisonExpression</code>. |
| * |
| * @param parent The parent of this expression |
| * @param expression The expression before the identifier |
| */ |
| public NullComparisonExpression(AbstractExpression parent, |
| String identifier, |
| AbstractExpression expression) { |
| |
| super(parent, identifier); |
| this.expression = expression; |
| |
| if (expression != null) { |
| expression.setParent(this); |
| } |
| } |
| |
| @Override |
| public void accept(ExpressionVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| public void acceptChildren(ExpressionVisitor visitor) { |
| getExpression().accept(visitor); |
| } |
| |
| @Override |
| protected void addChildrenTo(Collection<Expression> children) { |
| children.add(getExpression()); |
| } |
| |
| @Override |
| protected void addOrderedChildrenTo(List<Expression> children) { |
| |
| // Expression |
| if (hasExpression()) { |
| children.add(expression); |
| children.add(buildStringExpression(SPACE)); |
| } |
| |
| // Identifier |
| children.add(buildStringExpression(getIdentifier())); |
| } |
| |
| @Override |
| public JPQLQueryBNF findQueryBNF(Expression expression) { |
| |
| if (this.expression == expression) { |
| return expression.getQueryBNF(); |
| } |
| |
| return super.findQueryBNF(expression); |
| } |
| |
| /** |
| * Returns the actual <b>IS</b> found in the string representation of the JPQL query, which has |
| * the actual case that was used. |
| * |
| * @return The <b>IS</b> identifier that was actually parsed, or an empty string if it was not |
| * parsed |
| */ |
| public String getActualIsIdentifier() { |
| return (isIdentifier != null) ? isIdentifier : ExpressionTools.EMPTY_STRING; |
| } |
| |
| /** |
| * Returns the actual <b>Not</b> found in the string representation of the JPQL query, which has |
| * the actual case that was used. |
| * |
| * @return The <b>NOT</b> identifier that was actually parsed, or an empty string if it was not parsed |
| */ |
| public String getActualNotIdentifier() { |
| return (notIdentifier != null) ? notIdentifier : ExpressionTools.EMPTY_STRING; |
| } |
| |
| /** |
| * Returns the actual <b>NULL</b> found in the string representation of the JPQL query, which has |
| * the actual case that was used. |
| * |
| * @return The <b>NULL</b> identifier that was actually parsed |
| */ |
| public String getActualNullIdentifier() { |
| return nullIdentifier; |
| } |
| |
| /** |
| * Returns the expression being tested for being <code>null</code>. |
| * |
| * @return Either the parsed expression or the <code>null</code>-expression |
| */ |
| public Expression getExpression() { |
| if (expression == null) { |
| expression = buildNullExpression(); |
| } |
| return expression; |
| } |
| |
| /** |
| * Returns the identifier for this expression that may include <b>NOT</b> if it was parsed. |
| * |
| * @return Either <b>IS NULL</b> or <b>IS NOT NULL</b> |
| */ |
| public String getIdentifier() { |
| return (notIdentifier != null) ? IS_NOT_NULL : IS_NULL; |
| } |
| |
| @Override |
| public JPQLQueryBNF getQueryBNF() { |
| return getQueryBNF(NullComparisonExpressionBNF.ID); |
| } |
| |
| /** |
| * Determines whether the expression preceding the identifier was parsed. |
| * |
| * @return <code>true</code> the expression preceding the identifier was parsed; |
| * <code>false</code> otherwise |
| */ |
| public boolean hasExpression() { |
| return expression != null && |
| !expression.isNull(); |
| } |
| |
| /** |
| * Determines whether <b>NOT</b> is used in the query. |
| * |
| * @return <code>true</code> if <b>NOT</b> is present in the query; <code>false</code> otherwise |
| */ |
| public boolean hasNot() { |
| return notIdentifier != null; |
| } |
| |
| @Override |
| protected void parse(WordParser wordParser, boolean tolerant) { |
| |
| // 'IS' |
| isIdentifier = wordParser.moveForward(IS); |
| |
| wordParser.skipLeadingWhitespace(); |
| |
| // 'NOT' |
| if (wordParser.startsWithIdentifier(NOT)) { |
| notIdentifier = wordParser.moveForward(NOT); |
| wordParser.skipLeadingWhitespace(); |
| setText(IS_NOT_NULL); |
| } |
| else { |
| setText(IS_NULL); |
| } |
| |
| // 'NULL' |
| nullIdentifier = wordParser.moveForward(NULL); |
| } |
| |
| @Override |
| protected void toParsedText(StringBuilder writer, boolean actual) { |
| |
| if (hasExpression()) { |
| expression.toParsedText(writer, actual); |
| writer.append(SPACE); |
| } |
| |
| if (actual) { |
| |
| writer.append(isIdentifier); |
| writer.append(SPACE); |
| |
| if (notIdentifier != null) { |
| writer.append(notIdentifier); |
| writer.append(SPACE); |
| } |
| |
| writer.append(nullIdentifier); |
| } |
| else { |
| writer.append(getIdentifier()); |
| } |
| } |
| } |