| /* |
| * 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.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| import org.eclipse.persistence.jpa.jpql.ExpressionTools; |
| import org.eclipse.persistence.jpa.jpql.WordParser; |
| |
| /** |
| * A <b>WHEN</b> predicate is used to calculate a condition and when it's true, its <b>THEN</b> will |
| * be executed. |
| * |
| * <div><b>BNF:</b> <code>when_clause ::= WHEN conditional_expression THEN scalar_expression</code><p></p></div> |
| * or |
| * <div><b>BNF:</b> <code>simple_when_clause ::= WHEN scalar_expression THEN scalar_expression</code><p></p></div> |
| * |
| * @version 2.5 |
| * @since 2.3 |
| * @author Pascal Filion |
| */ |
| public final class WhenClause extends AbstractExpression { |
| |
| /** |
| * Determines whether a whitespace was parsed after the identifier <b>THEN</b>. |
| */ |
| private boolean hasSpaceAfterThen; |
| |
| /** |
| * Determines whether a whitespace was parsed after the identifier <b>WHEN</b>. |
| */ |
| private boolean hasSpaceAfterWhen; |
| |
| /** |
| * Determines whether a whitespace was parsed after the conditional expression. |
| */ |
| private boolean hasSpaceAfterWhenExpression; |
| |
| /** |
| * The {@link Expression} representing the expression following the identifier <b>THEN</b>. |
| */ |
| private AbstractExpression thenExpression; |
| |
| /** |
| * The actual <b>THEN</b> identifier found in the string representation of the JPQL query. |
| */ |
| private String thenIdentifier; |
| |
| /** |
| * The {@link Expression} representing the conditional predicate of the clause. |
| */ |
| private AbstractExpression whenExpression; |
| |
| /** |
| * The actual <b>WHEN</b> identifier found in the string representation of the JPQL query. |
| */ |
| private String whenIdentifier; |
| |
| /** |
| * Creates a new <code>WhenClause</code>. |
| * |
| * @param parent The parent of this expression |
| */ |
| public WhenClause(AbstractExpression parent) { |
| super(parent, WHEN); |
| } |
| |
| @Override |
| public void accept(ExpressionVisitor visitor) { |
| visitor.visit(this); |
| } |
| |
| @Override |
| public void acceptChildren(ExpressionVisitor visitor) { |
| getWhenExpression().accept(visitor); |
| getThenExpression().accept(visitor); |
| } |
| |
| @Override |
| protected void addChildrenTo(Collection<Expression> children) { |
| children.add(getWhenExpression()); |
| children.add(getThenExpression()); |
| } |
| |
| @Override |
| protected void addOrderedChildrenTo(List<Expression> children) { |
| |
| // WHEN |
| children.add(buildStringExpression(WHEN)); |
| |
| if (hasSpaceAfterWhen) { |
| children.add(buildStringExpression(SPACE)); |
| } |
| |
| // WHEN Expression |
| if (whenExpression != null) { |
| children.add(whenExpression); |
| } |
| |
| if (hasSpaceAfterWhenExpression) { |
| children.add(buildStringExpression(SPACE)); |
| } |
| |
| // THEN |
| if (thenIdentifier != null) { |
| children.add(buildStringExpression(THEN)); |
| } |
| |
| if (hasSpaceAfterThen) { |
| children.add(buildStringExpression(SPACE)); |
| } |
| |
| // THEN expression |
| if (thenExpression != null) { |
| children.add(thenExpression); |
| } |
| } |
| |
| /** |
| * Creates a new {@link CollectionExpression} that will wrap the single <code><b>WHEN </b></code> |
| * expression. |
| * |
| * @return The single <code><b>WHEN</b></code> expression represented by a temporary collection |
| */ |
| public CollectionExpression buildWhenCollectionExpression() { |
| |
| List<AbstractExpression> children = new ArrayList<AbstractExpression>(1); |
| children.add(getWhenExpression()); |
| |
| List<Boolean> commas = new ArrayList<Boolean>(1); |
| commas.add(Boolean.FALSE); |
| |
| List<Boolean> spaces = new ArrayList<Boolean>(1); |
| spaces.add(hasSpaceAfterWhenExpression); |
| |
| return new CollectionExpression(this, children, commas, spaces, true); |
| } |
| |
| @Override |
| public JPQLQueryBNF findQueryBNF(Expression expression) { |
| |
| if ((whenExpression != null) && whenExpression.isAncestor(expression)) { |
| return getQueryBNF(InternalWhenClauseBNF.ID); |
| } |
| |
| if ((thenExpression != null) && thenExpression.isAncestor(expression)) { |
| return getQueryBNF(ScalarExpressionBNF.ID); |
| } |
| |
| return super.findQueryBNF(expression); |
| } |
| |
| /** |
| * Returns the actual <b>THEN</b> found in the string representation of the JPQL query, which |
| * has the actual case that was used. |
| * |
| * @return The <b>THEN</b> identifier that was actually parsed, or an empty string if it was not parsed |
| */ |
| public String getActualThenIdentifier() { |
| return (thenIdentifier != null) ? thenIdentifier : ExpressionTools.EMPTY_STRING; |
| } |
| |
| /** |
| * Returns the actual <b>WHEN</b> found in the string representation of the JPQL query, which |
| * has the actual case that was used. |
| * |
| * @return The <b>WHEN</b> identifier that was actually parsed |
| */ |
| public String getActualWhenIdentifier() { |
| return whenIdentifier; |
| } |
| |
| @Override |
| public JPQLQueryBNF getQueryBNF() { |
| return getQueryBNF(WhenClauseBNF.ID); |
| } |
| |
| /** |
| * Returns the {@link Expression} representing the expression following the identifier <b>THEN</b>. |
| * |
| * @return The expression representing the expression executed if the predicate is true |
| */ |
| public AbstractExpression getThenExpression() { |
| if (thenExpression == null) { |
| thenExpression = buildNullExpression(); |
| } |
| return thenExpression; |
| } |
| |
| /** |
| * Returns the {@link Expression} representing the conditional predicate of the clause. |
| * |
| * @return The expression following the <b>WHEN</b> identifier |
| */ |
| public AbstractExpression getWhenExpression() { |
| if (whenExpression == null) { |
| whenExpression = buildNullExpression(); |
| } |
| return whenExpression; |
| } |
| |
| /** |
| * Determines whether a whitespace was parsed after <b>THEN</b>. |
| * |
| * @return <code>true</code> if there was a whitespace after <b>THEN</b>; <code>false</code> otherwise |
| */ |
| public boolean hasSpaceAfterThen() { |
| return hasSpaceAfterThen; |
| } |
| |
| /** |
| * Determines whether a whitespace was parsed after <b>WHEN</b>. |
| * |
| * @return <code>true</code> if there was a whitespace after <b>WHEN</b>; <code>false</code> otherwise |
| */ |
| public boolean hasSpaceAfterWhen() { |
| return hasSpaceAfterWhen; |
| } |
| |
| /** |
| * Determines whether a whitespace was parsed after the conditional expression. |
| * |
| * @return <code>true</code> if there was a whitespace after the conditional expression; |
| * <code>false</code> otherwise |
| */ |
| public boolean hasSpaceAfterWhenExpression() { |
| return hasSpaceAfterWhenExpression; |
| } |
| |
| /** |
| * Determines whether the identifier <b>THEN</b> was part of the query. |
| * |
| * @return <code>true</code> if the identifier <b>THEN</b> was parsed; <code>false</code> otherwise |
| */ |
| public boolean hasThen() { |
| return thenIdentifier != null; |
| } |
| |
| /** |
| * Determines whether the <b>THEN</b> expression of the query was parsed. |
| * |
| * @return <code>true</code> the <b>THEN</b> expression was parsed; <code>false</code> if nothing |
| * was parsed |
| */ |
| public boolean hasThenExpression() { |
| return thenExpression != null && |
| !thenExpression.isNull(); |
| } |
| |
| /** |
| * Determines whether the conditional expression of the query was parsed. |
| * |
| * @return <code>true</code> the conditional expression was parsed; <code>false</code> if nothing |
| * was parsed |
| */ |
| public boolean hasWhenExpression() { |
| return whenExpression != null && |
| !whenExpression.isNull(); |
| } |
| |
| @Override |
| protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression) { |
| return word.equalsIgnoreCase(WHEN) || |
| word.equalsIgnoreCase(THEN) || |
| word.equalsIgnoreCase(ELSE) || |
| word.equalsIgnoreCase(END) || |
| super.isParsingComplete(wordParser, word, expression); |
| } |
| |
| @Override |
| protected void parse(WordParser wordParser, boolean tolerant) { |
| |
| // Parse 'WHEN' |
| whenIdentifier = wordParser.moveForward(WHEN); |
| hasSpaceAfterWhen = wordParser.skipLeadingWhitespace() > 0; |
| |
| // Parse the expression |
| whenExpression = parse(wordParser, InternalWhenClauseBNF.ID, tolerant); |
| hasSpaceAfterWhenExpression = wordParser.skipLeadingWhitespace() > 0; |
| |
| // Parse 'THEN' |
| if (!tolerant || wordParser.startsWithIdentifier(THEN)) { |
| thenIdentifier = wordParser.moveForward(THEN); |
| hasSpaceAfterThen = wordParser.skipLeadingWhitespace() > 0; |
| } |
| |
| // Parse the then expression |
| thenExpression = parse(wordParser, ScalarExpressionBNF.ID, tolerant); |
| } |
| |
| @Override |
| protected void toParsedText(StringBuilder writer, boolean actual) { |
| |
| // 'WHEN' |
| writer.append(actual ? whenIdentifier : WHEN); |
| |
| if (hasSpaceAfterWhen) { |
| writer.append(SPACE); |
| } |
| |
| // Expression |
| if (whenExpression != null) { |
| whenExpression.toParsedText(writer, actual); |
| } |
| |
| if (hasSpaceAfterWhenExpression) { |
| writer.append(SPACE); |
| } |
| |
| // 'THEN' |
| if (thenIdentifier != null) { |
| writer.append(actual ? thenIdentifier : THEN); |
| } |
| |
| if (hasSpaceAfterThen) { |
| writer.append(SPACE); |
| } |
| |
| // Then expression |
| if (thenExpression != null) { |
| thenExpression.toParsedText(writer, actual); |
| } |
| } |
| } |