/*******************************************************************************
* Copyright (c) 2006, 2015 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 v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* 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 <code><b>SELECT</b></code> query is an operation that retrieves data from one or more tables or
* views.
* <p>
* JPA:
* <div><b>BNF:</b> <code>select_statement ::= select_clause
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]</code></div>
* <p>
* EclipseLink 2.4:
* <div><b>BNF:</b> <code>select_statement ::= select_clause
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]
* {union_clause}*</code></div>
* <p>
* HQL query (EclipseLink 2.5):
* <div><b>BNF:</b> <code>select_statement ::= [select_clause]
* from_clause
* [where_clause]
* [groupby_clause]
* [having_clause]
* [orderby_clause]
* {union_clause}*</code></div>
* <p>
*
* @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 <b>ORDER BY</b> identifier.
*/
private boolean hasSpaceBeforeOrderBy;
/**
* Determines whether there is a whitespace after the select statement parsed by the superclass
* and the <b>UNION</b> identifier.
*/
private boolean hasSpaceBeforeUnion;
/**
* The <b>ORDER BY</b> expression.
*/
private AbstractExpression orderByClause;
/**
* The <b>UNION</b> expression.
*/
private AbstractExpression unionClauses;
/**
* Creates a new <code>SelectStatement</code>.
*
* @param parent The parent of this expression
*/
public SelectStatement(AbstractExpression parent) {
super(parent);
}
/**
* {@inheritDoc}
*/
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
*/
@Override
public void acceptChildren(ExpressionVisitor visitor) {
super.acceptChildren(visitor);
getOrderByClause().accept(visitor);
getUnionClauses().accept(visitor);
}
/**
* {@inheritDoc}
*/
@Override
protected void addChildrenTo(Collection<Expression> children) {
super.addChildrenTo(children);
children.add(getOrderByClause());
children.add(getUnionClauses());
}
/**
* {@inheritDoc}
*/
@Override
protected void addOrderedChildrenTo(List<Expression> 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);
}
}
/**
* {@inheritDoc}
*/
@Override
protected FromClause buildFromClause() {
return new FromClause(this);
}
/**
* {@inheritDoc}
*/
@Override
protected SelectClause buildSelectClause() {
return new SelectClause(this);
}
/**
* {@inheritDoc}
*/
@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 <b>ORDER BY</b> clause.
*
* @return The expression representing the <b>ORDER BY</b> clause
*/
public Expression getOrderByClause() {
if (orderByClause == null) {
orderByClause = buildNullExpression();
}
return orderByClause;
}
/**
* {@inheritDoc}
*/
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(SelectStatementBNF.ID);
}
/**
* Returns the {@link Expression} representing the <b>UNION</b> clauses.
*
* @return The {@link Expression} representing the <b>UNION</b> clauses
*/
public Expression getUnionClauses() {
if (unionClauses == null) {
unionClauses = buildNullExpression();
}
return unionClauses;
}
/**
* Determines whether the <b>ORDER BY</b> clause is defined or not.
*
* @return <code>true</code> if the query that got parsed had the <b>ORDER BY</b> clause
*/
public boolean hasOrderByClause() {
return orderByClause != null &&
!orderByClause.isNull();
}
/**
* Determines whether a whitespace was parsed before the <b>ORDER BY</b> clause. In some cases,
* the space could be owned by a child of the previous clause.
*
* @return <code>true</code> if there was a whitespace before the <b>ORDER BY</b>; <code>false</code>
* otherwise
*/
public boolean hasSpaceBeforeOrderBy() {
return hasSpaceBeforeOrderBy;
}
/**
* Determines whether a whitespace was parsed before the <b>UNION</b> clause. In some cases,
* the space could be owned by a child of the previous clause.
*
* @return <code>true</code> if there was a whitespace before the <b>UNION</b>;
* <code>false</code> otherwise
*/
public boolean hasSpaceBeforeUnion() {
return hasSpaceBeforeUnion;
}
/**
* Determines whether at least one <b>UNION</b> clause was defined.
*
* @return <code>true</code> if the query that got parsed had the <b>UNION</b> clauses
*/
public boolean hasUnionClauses() {
return unionClauses != null &&
!unionClauses.isNull();
}
/**
* {@inheritDoc}
*/
@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);
}
/**
* {@inheritDoc}
*/
@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);
}
}
/**
* {@inheritDoc}
*/
@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);
}
}
}