org.eclipse.persistence.jpa.jpql.parser.SelectStatement Maven / Gradle / Ivy
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/*
* Copyright (c) 2006, 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
//
package org.eclipse.persistence.jpa.jpql.parser;
import java.util.Collection;
import java.util.List;
import org.eclipse.persistence.jpa.jpql.WordParser;
/**
* A SELECT query is an operation that retrieves data from one or more tables or
* views.
*
* JPA:
*
BNF: select_statement ::= select_clause
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]
*
* EclipseLink 2.4:
*
BNF: select_statement ::= select_clause
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]
* {union_clause}*
*
* HQL query (EclipseLink 2.5):
*
BNF: select_statement ::= [select_clause]
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]
* {union_clause}*
*
*
* @see FromClause
* @see GroupByClause
* @see HavingClause
* @see HierarchicalQueryClause
* @see OrderByClause
* @see SelectClause
* @see UnionClause
* @see WhereClause
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
public final class SelectStatement extends AbstractSelectStatement {
/**
* Determines whether there is a whitespace after the select statement parsed by the superclass
* and the ORDER BY identifier.
*/
private boolean hasSpaceBeforeOrderBy;
/**
* Determines whether there is a whitespace after the select statement parsed by the superclass
* and the UNION identifier.
*/
private boolean hasSpaceBeforeUnion;
/**
* The ORDER BY expression.
*/
private AbstractExpression orderByClause;
/**
* The UNION expression.
*/
private AbstractExpression unionClauses;
/**
* Creates a new SelectStatement.
*
* @param parent The parent of this expression
*/
public SelectStatement(AbstractExpression parent) {
super(parent);
}
@Override
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
@Override
public void acceptChildren(ExpressionVisitor visitor) {
super.acceptChildren(visitor);
getOrderByClause().accept(visitor);
getUnionClauses().accept(visitor);
}
@Override
protected void addChildrenTo(Collection children) {
super.addChildrenTo(children);
children.add(getOrderByClause());
children.add(getUnionClauses());
}
@Override
protected void addOrderedChildrenTo(List children) {
super.addOrderedChildrenTo(children);
if (hasSpaceBeforeOrderBy) {
children.add(buildStringExpression(SPACE));
}
// 'ORDER BY' clause
if (orderByClause != null) {
children.add(orderByClause);
}
// 'UNION' clauses
if (unionClauses != null) {
children.add(unionClauses);
}
}
@Override
protected FromClause buildFromClause() {
return new FromClause(this);
}
@Override
protected SelectClause buildSelectClause() {
return new SelectClause(this);
}
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((orderByClause != null) && orderByClause.isAncestor(expression)) {
return orderByClause.getQueryBNF();
}
if ((unionClauses != null) && unionClauses.isAncestor(expression)) {
return getQueryBNF(UnionClauseBNF.ID);
}
return super.findQueryBNF(expression);
}
/**
* Returns the {@link Expression} representing the ORDER BY clause.
*
* @return The expression representing the ORDER BY clause
*/
public Expression getOrderByClause() {
if (orderByClause == null) {
orderByClause = buildNullExpression();
}
return orderByClause;
}
@Override
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(SelectStatementBNF.ID);
}
/**
* Returns the {@link Expression} representing the UNION clauses.
*
* @return The {@link Expression} representing the UNION clauses
*/
public Expression getUnionClauses() {
if (unionClauses == null) {
unionClauses = buildNullExpression();
}
return unionClauses;
}
/**
* Determines whether the ORDER BY clause is defined or not.
*
* @return true if the query that got parsed had the ORDER BY clause
*/
public boolean hasOrderByClause() {
return orderByClause != null &&
!orderByClause.isNull();
}
/**
* Determines whether a whitespace was parsed before the ORDER BY clause. In some cases,
* the space could be owned by a child of the previous clause.
*
* @return true if there was a whitespace before the ORDER BY; false
* otherwise
*/
public boolean hasSpaceBeforeOrderBy() {
return hasSpaceBeforeOrderBy;
}
/**
* Determines whether a whitespace was parsed before the UNION clause. In some cases,
* the space could be owned by a child of the previous clause.
*
* @return true if there was a whitespace before the UNION;
* false otherwise
*/
public boolean hasSpaceBeforeUnion() {
return hasSpaceBeforeUnion;
}
/**
* Determines whether at least one UNION clause was defined.
*
* @return true if the query that got parsed had the UNION clauses
*/
public boolean hasUnionClauses() {
return unionClauses != null &&
!unionClauses.isNull();
}
@Override
protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression) {
if (word.equalsIgnoreCase(UNION) ||
word.equalsIgnoreCase(INTERSECT) ||
word.equalsIgnoreCase(EXCEPT)) {
return false;
}
return super.isParsingComplete(wordParser, word, expression);
}
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
super.parse(wordParser, tolerant);
hasSpaceBeforeOrderBy = wordParser.skipLeadingWhitespace() > 0;
// Parse 'ORDER BY'
if (wordParser.startsWithIdentifier(ORDER_BY)) {
orderByClause = new OrderByClause(this);
orderByClause.parse(wordParser, tolerant);
}
// Parse the union clauses and make sure the grammar supports it
if (getQueryBNF(UnionClauseBNF.ID) != null) {
hasSpaceBeforeUnion = wordParser.skipLeadingWhitespace() > 0;
unionClauses = parse(wordParser, UnionClauseBNF.ID, tolerant);
}
}
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
super.toParsedText(writer, actual);
if (hasSpaceBeforeOrderBy) {
writer.append(SPACE);
}
// 'ORDER BY' clause
if (hasOrderByClause()) {
orderByClause.toParsedText(writer, actual);
}
if (hasSpaceBeforeUnion) {
writer.append(SPACE);
}
// 'UNION' clauses
if (hasUnionClauses()) {
unionClauses.toParsedText(writer, actual);
}
}
}