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/*
* 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.WordParser;
/**
* A query is an operation that retrieves data from one or more tables or views. In this reference,
* a top-level SELECT statement is called a query, and a query nested within
* another SQL statement is called a subquery.
*
* @see SelectStatement
* @see SimpleSelectStatement
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
public abstract class AbstractSelectStatement extends AbstractExpression {
/**
* The FROM clause of this select statement.
*/
private AbstractExpression fromClause;
/**
* The GROUP BY clause of this select statement.
*/
private AbstractExpression groupByClause;
/**
* Determines whether there is a whitespace after the identifier FROM.
*/
private boolean hasSpaceAfterFrom;
/**
* Determines whether there is a whitespace after the identifier GROUP BY.
*/
private boolean hasSpaceAfterGroupBy;
/**
* Determines whether there is a whitespace after the identifier SELECT.
*/
private boolean hasSpaceAfterSelect;
/**
* Determines whether there is a whitespace after the identifier WHERE.
*/
private boolean hasSpaceAfterWhere;
/**
* The HAVING clause of this select statement.
*/
private AbstractExpression havingClause;
/**
* The SELECT clause of this select statement.
*/
private AbstractExpression selectClause;
/**
* The WHERE clause of this select statement.
*/
private AbstractExpression whereClause;
/**
* Creates a new AbstractSelectStatement.
*
* @param parent The parent of this expression
*/
protected AbstractSelectStatement(AbstractExpression parent) {
super(parent);
}
@Override
public void acceptChildren(ExpressionVisitor visitor) {
getSelectClause().accept(visitor);
getFromClause().accept(visitor);
getWhereClause().accept(visitor);
getGroupByClause().accept(visitor);
getHavingClause().accept(visitor);
}
@Override
protected void addChildrenTo(Collection children) {
children.add(getSelectClause());
children.add(getFromClause());
children.add(getWhereClause());
children.add(getGroupByClause());
children.add(getHavingClause());
}
@Override
protected void addOrderedChildrenTo(List children) {
// SELECT clause
if (selectClause != null) {
children.add(selectClause);
}
// Space between SELECT and FROM clauses
if (hasSpaceAfterSelect) {
children.add(buildStringExpression(SPACE));
}
// FROM clause
if (fromClause != null) {
children.add(fromClause);
}
// Space between the FROM clause and an optional clause
if (hasSpaceAfterFrom) {
children.add(buildStringExpression(SPACE));
}
// WHERE clause
if (whereClause != null) {
children.add(whereClause);
}
// Space between WHERE clause and another optional clause
if (hasSpaceAfterWhere) {
children.add(buildStringExpression(SPACE));
}
// GROUP BY clause
if (groupByClause != null) {
children.add(groupByClause);
}
// Space between GROUP BY clause and another optional clause
if (hasSpaceAfterGroupBy) {
children.add(buildStringExpression(SPACE));
}
// HAVING clause
if (havingClause != null) {
children.add(havingClause);
}
}
/**
* Creates the expression representing the from clause of this select statement.
*
* @return A new from clause, null can't be returned
*/
protected abstract AbstractFromClause buildFromClause();
/**
* Creates the expression representing the select clause of this select statement.
*
* @return A new from clause, null can't be returned
*/
protected abstract AbstractSelectClause buildSelectClause();
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((selectClause != null) && selectClause.isAncestor(expression)) {
return selectClause.getQueryBNF();
}
if ((fromClause != null) && fromClause.isAncestor(expression)) {
return fromClause.getQueryBNF();
}
if ((whereClause != null) && whereClause.isAncestor(expression)) {
return whereClause.getQueryBNF();
}
if ((groupByClause != null) && groupByClause.isAncestor(expression)) {
return groupByClause.getQueryBNF();
}
if ((havingClause != null) && havingClause.isAncestor(expression)) {
return havingClause.getQueryBNF();
}
return super.findQueryBNF(expression);
}
/**
* Returns the {@link Expression} representing the FROM clause.
*
* @return The expression representing the FROM clause
*/
public final Expression getFromClause() {
if (fromClause == null) {
fromClause = buildNullExpression();
}
return fromClause;
}
/**
* Returns the {@link Expression} representing the GROUP BY clause.
*
* @return The expression representing the GROUP BY clause
*/
public final Expression getGroupByClause() {
if (groupByClause == null) {
groupByClause = buildNullExpression();
}
return groupByClause;
}
/**
* Returns the {@link Expression} representing the HAVING clause.
*
* @return The expression representing the HAVING clause
*/
public final Expression getHavingClause() {
if (havingClause == null) {
havingClause = buildNullExpression();
}
return havingClause;
}
/**
* Returns the {@link AbstractSelectClause} representing the SELECT clause.
*
* @return The expression representing the SELECT clause
*/
public final Expression getSelectClause() {
if (selectClause == null) {
selectClause = buildNullExpression();
}
return selectClause;
}
/**
* Returns the {@link Expression} representing the WHERE clause.
*
* @return The expression representing the WHERE clause
*/
public final Expression getWhereClause() {
if (whereClause == null) {
whereClause = buildNullExpression();
}
return whereClause;
}
/**
* Determines whether the FROM clause was parsed or not.
*
* @return true if the query that got parsed had the FROM clause
*/
public final boolean hasFromClause() {
return fromClause != null &&
!fromClause.isNull();
}
/**
* Determines whether the GROUP BY clause was parsed or not.
*
* @return true if the query that got parsed had the GROUP BY clause
*/
public final boolean hasGroupByClause() {
return groupByClause != null &&
!groupByClause.isNull();
}
/**
* Determines whether the HAVING clause was parsed or not.
*
* @return true if the query that got parsed had the HAVING clause
*/
public final boolean hasHavingClause() {
return havingClause != null &&
!havingClause.isNull();
}
/**
* Determines whether the SELECT clause was parsed or not.
*
* @return true if the query that got parsed had the HAVING clause
* @since 2.5
*/
public final boolean hasSelectClause() {
return selectClause != null &&
!selectClause.isNull();
}
/**
* Determines whether a whitespace was found after the FROM clause. In some cases, the
* space is owned by a child of the FROM clause.
*
* @return true if there was a whitespace after the FROM clause and owned by
* this expression; false otherwise
*/
public final boolean hasSpaceAfterFrom() {
return hasSpaceAfterFrom;
}
/**
* Determines whether a whitespace was found after the GROUP BY clause. In some cases, the
* space is owned by a child of the GROUP BY clause.
*
* @return true if there was a whitespace after the GROUP BY clause and owned
* by this expression; false otherwise
*/
public final boolean hasSpaceAfterGroupBy() {
return hasSpaceAfterGroupBy;
}
/**
* Determines whether a whitespace was found after the SELECT clause. In some cases, the
* space is owned by a child of the SELECT clause.
*
* @return true if there was a whitespace after the SELECT clause and owned
* by this expression; false otherwise
*/
public final boolean hasSpaceAfterSelect() {
return hasSpaceAfterSelect;
}
/**
* Determines whether a whitespace was found after the WHERE clause. In some cases, the
* space is owned by a child of the WHERE clause.
*
* @return true if there was a whitespace after the WHERE clause and owned by
* this expression; false otherwise
*/
public final boolean hasSpaceAfterWhere() {
return hasSpaceAfterWhere;
}
/**
* Determines whether the WHERE clause is defined.
*
* @return true if the query that got parsed had the WHERE clause
*/
public final boolean hasWhereClause() {
return whereClause != null &&
!whereClause.isNull();
}
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
// Parse 'SELECT' clause
if (wordParser.startsWithIdentifier(SELECT)) {
selectClause = buildSelectClause();
selectClause.parse(wordParser, tolerant);
hasSpaceAfterSelect = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'FROM' clause
if (wordParser.startsWithIdentifier(FROM)) {
fromClause = buildFromClause();
fromClause.parse(wordParser, tolerant);
hasSpaceAfterFrom = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'WHERE' clause
if (wordParser.startsWithIdentifier(WHERE)) {
whereClause = new WhereClause(this);
whereClause.parse(wordParser, tolerant);
hasSpaceAfterWhere = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'GROUP BY' clause
if (wordParser.startsWithIdentifier(GROUP_BY)) {
groupByClause = new GroupByClause(this);
groupByClause.parse(wordParser, tolerant);
hasSpaceAfterGroupBy = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'HAVING' clause
if (wordParser.startsWithIdentifier(HAVING)) {
havingClause = new HavingClause(this);
havingClause.parse(wordParser, tolerant);
}
if (!wordParser.isTail() && !shouldManageSpaceAfterClause()) {
if (hasSpaceAfterFrom &&
whereClause == null &&
groupByClause == null &&
havingClause == null) {
hasSpaceAfterFrom = false;
wordParser.moveBackward(1);
}
else if (hasSpaceAfterWhere &&
groupByClause == null &&
havingClause == null) {
hasSpaceAfterWhere = false;
wordParser.moveBackward(1);
}
else if (hasSpaceAfterGroupBy &&
havingClause == null) {
hasSpaceAfterGroupBy = false;
wordParser.moveBackward(1);
}
}
}
/**
* Determines whether the whitespace following the HAVING clause should be
* managed by this expression or not.
*
* @return true by default to keep the whitespace part of this expression;
* false to let the parent handle it
*/
protected boolean shouldManageSpaceAfterClause() {
return true;
}
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
// SELECT clause
if (selectClause != null) {
selectClause.toParsedText(writer, actual);
}
if (hasSpaceAfterSelect) {
writer.append(SPACE);
}
// FROM clause
if (fromClause != null) {
fromClause.toParsedText(writer, actual);
}
if (hasSpaceAfterFrom) {
writer.append(SPACE);
}
// WHERE clause
if (whereClause != null) {
whereClause.toParsedText(writer, actual);
}
if (hasSpaceAfterWhere) {
writer.append(SPACE);
}
// GROUP BY clause
if (groupByClause != null) {
groupByClause.toParsedText(writer, actual);
}
if (hasSpaceAfterGroupBy) {
writer.append(SPACE);
}
// HAVING clause
if (havingClause != null) {
havingClause.toParsedText(writer, actual);
}
}
}