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/*
* Copyright (c) 2012, 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.WordParser;
/**
* If a table contains hierarchical data, then rows can be selected in a hierarchical order using
* the hierarchical query clause.
*
* START WITH specifies the root row(s) of the hierarchy.
*
* CONNECT BY specifies the relationship between parent rows and child rows of
* the hierarchy.
*
*
BNF: hierarchical_query_clause ::= [start_with_clause] connectby_clause [order_siblings_by_clause]
*
* @see StartWithClause
* @see ConnectByClause
* @see OrderSiblingsByClause
*
* @version 2.5
* @since 2.5
* @author Pascal Filion
*/
public final class HierarchicalQueryClause extends AbstractExpression {
/**
* The {@link Expression} that represents the CONNECT BY clause.
*/
private AbstractExpression connectByClause;
/**
* Determines whether a whitespace was parsed after the CONNECT BY clause.
*/
private boolean hasSpaceAfterConnectByClause;
/**
* Determines whether a whitespace was parsed after the START WITH clause.
*/
private boolean hasSpaceAfterStartWithClause;
/**
* The {@link Expression} that represents the ORDER SIBLINGS BY clause.
*/
private AbstractExpression orderSiblingsByClause;
/**
* The {@link Expression} that represents the START WITH clause.
*/
private AbstractExpression startWithClause;
/**
* Creates a new HierarchicalQueryClause.
*
* @param parent The parent of this expression
*/
public HierarchicalQueryClause(AbstractExpression parent) {
super(parent);
}
@Override
public void accept(ExpressionVisitor visitor) {
acceptUnknownVisitor(visitor);
}
@Override
public void acceptChildren(ExpressionVisitor visitor) {
getStartWithClause().accept(visitor);
getConnectByClause().accept(visitor);
getOrderSiblingsByClause().accept(visitor);
}
@Override
protected void addChildrenTo(Collection children) {
super.addChildrenTo(children);
children.add(getStartWithClause());
children.add(getConnectByClause());
children.add(getOrderSiblingsByClause());
}
@Override
protected void addOrderedChildrenTo(List children) {
// START WITH clause
if (startWithClause != null) {
children.add(startWithClause);
}
if (hasSpaceAfterStartWithClause) {
children.add(buildStringExpression(SPACE));
}
// CONNECT BY clause
if (connectByClause != null) {
children.add(connectByClause);
}
if (hasSpaceAfterConnectByClause) {
children.add(buildStringExpression(SPACE));
}
// ORDER SIBLINGS BY clause
if (orderSiblingsByClause != null) {
children.add(orderSiblingsByClause);
}
}
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((startWithClause != null) && startWithClause.isAncestor(expression)) {
return getQueryBNF(StartWithClauseBNF.ID);
}
if ((connectByClause != null) && connectByClause.isAncestor(expression)) {
return getQueryBNF(ConnectByClauseBNF.ID);
}
if ((orderSiblingsByClause != null) && orderSiblingsByClause.isAncestor(expression)) {
return getQueryBNF(OrderSiblingsByClauseBNF.ID);
}
return super.findQueryBNF(expression);
}
/**
* Returns the {@link Expression} representing the CONNECT BY clause.
*
* @return The expression representing the CONNECT BY clause
*/
public Expression getConnectByClause() {
if (connectByClause == null) {
connectByClause = buildNullExpression();
}
return connectByClause;
}
/**
* Returns the {@link Expression} representing the ORDER SIBLINGS BY clause.
*
* @return The expression representing the ORDER SIBLINGS BY clause
*/
public Expression getOrderSiblingsByClause() {
if (orderSiblingsByClause == null) {
orderSiblingsByClause = buildNullExpression();
}
return orderSiblingsByClause;
}
@Override
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(HierarchicalQueryClauseBNF.ID);
}
/**
* Returns the {@link Expression} representing the START WITH clause.
*
* @return The expression representing the START WITH clause
*/
public Expression getStartWithClause() {
if (startWithClause == null) {
startWithClause = buildNullExpression();
}
return startWithClause;
}
/**
* Determines whether the CONNECT BY clause is defined.
*
* @return true if the query that got parsed had the CONNECT BY clause
*/
public boolean hasConnectByClause() {
return connectByClause != null &&
!connectByClause.isNull();
}
/**
* Determines whether the ORDER SIBLINGS BY clause is defined.
*
* @return true if the query that got parsed had the ORDER SIBLINGS BY clause
*/
public boolean hasOrderSiblingsByClause() {
return orderSiblingsByClause != null &&
!orderSiblingsByClause.isNull();
}
/**
* Determines whether a whitespace was found after the CONNECT BY clause. In
* some cases, the space is owned by a child of the hierarchical query clause.
*
* @return true if there was a whitespace after the CONNECT BY
* clause and owned by this expression; false otherwise
*/
public boolean hasSpaceAfterConnectByClause() {
return hasSpaceAfterConnectByClause;
}
/**
* Determines whether a whitespace was found after the START WITH clause. In
* some cases, the space is owned by a child of the hierarchical query clause.
*
* @return true if there was a whitespace after the START WITH
* clause and owned by this expression; false otherwise
*/
public boolean hasSpaceAfterStartWithClause() {
return hasSpaceAfterStartWithClause;
}
/**
* Determines whether the START WITH clause is defined.
*
* @return true if the query that got parsed had the START WITH clause
*/
public boolean hasStartWithClause() {
return startWithClause != null &&
!startWithClause.isNull();
}
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
int count = 0;
// START WITH clause
if (wordParser.startsWithIdentifier(START_WITH)) {
startWithClause = new StartWithClause(this);
startWithClause.parse(wordParser, tolerant);
count = wordParser.skipLeadingWhitespace();
hasSpaceAfterStartWithClause = (count > 0);
}
// CONNECT BY clause
if (wordParser.startsWithIdentifier(CONNECT_BY)) {
connectByClause = new ConnectByClause(this);
connectByClause.parse(wordParser, tolerant);
count = wordParser.skipLeadingWhitespace();
hasSpaceAfterConnectByClause = (count > 0);
}
// ORDER SIBLINGS BY clause
if (wordParser.startsWithIdentifier(ORDER_SIBLINGS_BY)) {
orderSiblingsByClause = new OrderSiblingsByClause(this);
orderSiblingsByClause.parse(wordParser, tolerant);
}
// Let's the parent statement own the whitespace
if (hasSpaceAfterStartWithClause &&
connectByClause == null &&
orderSiblingsByClause == null) {
hasSpaceAfterStartWithClause = false;
wordParser.moveBackward(count);
}
else if (hasSpaceAfterConnectByClause &&
orderSiblingsByClause == null) {
hasSpaceAfterConnectByClause = false;
wordParser.moveBackward(count);
}
}
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
// START WITH clause
if (startWithClause != null) {
startWithClause.toParsedText(writer, actual);
if (hasSpaceAfterStartWithClause) {
writer.append(SPACE);
}
}
// CONNECT BY clause
if (connectByClause != null) {
connectByClause.toParsedText(writer, actual);
if (hasSpaceAfterConnectByClause) {
writer.append(SPACE);
}
}
// ORDER SIBLINGS BY clause
if (orderSiblingsByClause != null) {
orderSiblingsByClause.toParsedText(writer, actual);
}
}
}