| /* |
| * Copyright (c) 1998, 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 from Oracle TopLink |
| package org.eclipse.persistence.internal.expressions; |
| |
| import org.eclipse.persistence.descriptors.ClassDescriptor; |
| import org.eclipse.persistence.exceptions.QueryException; |
| import org.eclipse.persistence.expressions.*; |
| import org.eclipse.persistence.internal.helper.DatabaseField; |
| import org.eclipse.persistence.internal.queries.ReportItem; |
| import org.eclipse.persistence.internal.sessions.AbstractSession; |
| import org.eclipse.persistence.mappings.querykeys.DirectQueryKey; |
| import org.eclipse.persistence.mappings.querykeys.QueryKey; |
| import org.eclipse.persistence.queries.ReportQuery; |
| |
| /** |
| * Represents an alias to a item selected by a from clause sub-select. |
| */ |
| public class FromAliasExpression extends QueryKeyExpression { |
| protected ReportItem item; |
| protected ClassDescriptor containingDescriptor; |
| |
| public FromAliasExpression() { |
| super(); |
| } |
| |
| public FromAliasExpression(String name, Expression base) { |
| super(name, base); |
| } |
| |
| /** |
| * INTERNAL: |
| * Used for debug printing. |
| */ |
| @Override |
| public String descriptionOfNodeType() { |
| return "From Alias"; |
| } |
| |
| /** |
| * INTERNAL: |
| * If a descriptor cannot be found, then return null. |
| */ |
| @Override |
| public QueryKey getQueryKeyOrNull() { |
| if (!hasQueryKey) { |
| return null; |
| } |
| if (getContainingDescriptor() == null) { |
| // Assign an artificial query key to represent the alias. |
| DirectQueryKey alias = new DirectQueryKey(); |
| alias.setField(new DatabaseField(this.name)); |
| ReportQuery subQuery = ((FromSubSelectExpression)getBaseExpression()).getSubSelect().getSubQuery(); |
| alias.setDescriptor(subQuery.getDescriptor()); |
| this.queryKey = alias; |
| return alias; |
| } |
| return super.getQueryKeyOrNull(); |
| } |
| |
| |
| /** |
| * INTERNAL: |
| * If the alias is for a query key item, then return its descriptor. |
| * If it is for a function, then it has no descriptor. |
| */ |
| @Override |
| public ClassDescriptor getContainingDescriptor() { |
| AbstractSession session = getBuilder().getSession(); |
| if (this.containingDescriptor == null) { |
| Expression expression = getItem().getAttributeExpression(); |
| if (expression.isQueryKeyExpression()) { |
| // Need to ensure expression has a session before getting its descriptor. |
| if (expression.getBuilder().getSession() == null) { |
| expression.getBuilder().setSession(session); |
| } |
| this.containingDescriptor = ((QueryKeyExpression)expression).getContainingDescriptor(); |
| return this.containingDescriptor; |
| } |
| return null; |
| } |
| return containingDescriptor; |
| } |
| |
| /** |
| * INTERNAL: |
| * Return the report item that this is an alias for. |
| */ |
| public ReportItem getItem() { |
| if (this.item == null) { |
| ReportQuery subQuery = ((FromSubSelectExpression)getBaseExpression()).getSubSelect().getSubQuery(); |
| this.item = subQuery.getItem(this.name); |
| if (this.item == null) { |
| throw QueryException.invalidQueryKeyInExpression(this.name); |
| } |
| } |
| return this.item; |
| } |
| } |