| /* |
| * 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 org.eclipse.persistence.jpa.jpql.WordParser; |
| |
| /** |
| * This {@link ResultVariableFactory} creates a new {@link ResultVariable} when the portion of the |
| * query to parse starts with or without <b>AS</b>. |
| * |
| * @see ResultVariable |
| * |
| * @version 2.5 |
| * @since 2.3 |
| * @author Pascal Filion |
| */ |
| @SuppressWarnings("nls") |
| public final class ResultVariableFactory extends ExpressionFactory { |
| |
| /** |
| * Caches the visitor that determines if the parent {@link Expression} is the top-level |
| * <code><b>SELECT</b></code> clause. |
| */ |
| private SelectClauseVisitor selectClauseVisitor; |
| |
| /** |
| * The unique identifier of this {@link ResultVariableFactory}. |
| */ |
| public static final String ID = "result_variable"; |
| |
| /** |
| * Creates a new <code>ResultVariableFactory</code>. |
| */ |
| public ResultVariableFactory() { |
| super(ID, Expression.AS); |
| } |
| |
| @Override |
| protected AbstractExpression buildExpression(AbstractExpression parent, |
| WordParser wordParser, |
| String word, |
| JPQLQueryBNF queryBNF, |
| AbstractExpression expression, |
| boolean tolerant) { |
| |
| SelectClauseVisitor visitor = selectClauseVisitor(); |
| |
| try { |
| if (expression != null) { |
| parent.accept(visitor); |
| if (!visitor.supported) { |
| expression = null; |
| } |
| } |
| } |
| finally { |
| visitor.supported = false; |
| } |
| |
| // There was already an expression parsed, we'll assume it's a valid |
| // expression and it will have an identification variable, and the identifier is optional |
| // Example: "SELECT e.salary / 1000D n" or "SELECT e.salary / 1000D AS n" |
| if (((expression != null) || word.equalsIgnoreCase(Expression.AS)) && |
| (word.indexOf(AbstractExpression.DOT) == -1)) { |
| |
| ResultVariable resultVariable = new ResultVariable(parent, expression); |
| resultVariable.parse(wordParser, tolerant); |
| return resultVariable; |
| } |
| |
| // Use the default factory |
| ExpressionFactory factory = getExpressionRegistry().getExpressionFactory(LiteralExpressionFactory.ID); |
| return factory.buildExpression(parent, wordParser, word, queryBNF, expression, tolerant); |
| } |
| |
| private SelectClauseVisitor selectClauseVisitor() { |
| if (selectClauseVisitor == null) { |
| selectClauseVisitor = new SelectClauseVisitor(); |
| } |
| return selectClauseVisitor; |
| } |
| |
| /** |
| * This visitor determines whether the result variable should set the parsed expression as the |
| * select expression or not. The allowed locations are: |
| * <ul> |
| * <li>Root: To support parsing a JPQL fragment.</li> |
| * <li>Top-level <code><b>SELECT</b></code> clause: default valid location.</li> |
| * <li>Subquery <code><b>SELECT</b></code> clause: to support from within the |
| * <code><b>FROM</b></code> clause.</li> |
| * </ul> |
| */ |
| private static class SelectClauseVisitor extends AbstractExpressionVisitor { |
| |
| /** |
| * Indicates if the result variable should have already parsed expression as its select expression. |
| */ |
| boolean supported; |
| |
| @Override |
| public void visit(JPQLExpression expression) { |
| this.supported = true; |
| } |
| |
| @Override |
| public void visit(SelectClause expression) { |
| this.supported = true; |
| } |
| |
| @Override |
| public void visit(SimpleSelectClause expression) { |
| this.supported = true; |
| } |
| } |
| } |