/*******************************************************************************
* 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.ExpressionTools;
import org.eclipse.persistence.jpa.jpql.WordParser;
/**
* This expression tests whether or not the collection designated by the collection-valued path
* expression is empty (i.e, has no elements).
*
* <div><b>BNF:</b> <code>empty_collection_comparison_expression ::= collection_valued_path_expression IS [NOT] EMPTY</code><p></div>
*
* @version 2.5
* @since 2.3
* @author Pascal Filion
*/
@SuppressWarnings("nls")
public final class EmptyCollectionComparisonExpression extends AbstractExpression {
/**
* The actual <b>EMPTY</b> identifier found in the string representation of the JPQL query.
*/
private String emptyIdentifier;
/**
* The {@link Expression} that represents the collection-valued path expression.
*/
private AbstractExpression expression;
/**
* Determines whether a whitespace was parsed after <b>IS</b>.
*/
private boolean hasSpaceAfterIs;
/**
* The actual <b>IS</b> identifier found in the string representation of the JPQL query.
*/
private String isIdentifier;
/**
* The actual <b>IS</b> identifier found in the string representation of the JPQL query.
*/
private String notIdentifier;
/**
* Creates a new <code>NullComparisonExpression</code>.
*
* @param parent The parent of this expression
* @param expression The {@link Expression} that represents the collection-valued path expression
*/
public EmptyCollectionComparisonExpression(AbstractExpression parent, AbstractExpression expression) {
super(parent);
updateExpression(expression);
}
/**
* Creates a new <code>NullComparisonExpression</code>.
*
* @param parent The parent of this expression
* @param identifier The actual identifier, which is either {@link Expression#IS_EMPTY IS_EMPTY}
* or {@link Expression#IS_NOT_EMPTY IS_NOT_EMPTY}
* @param expression The {@link Expression} that represents the collection-valued path expression
*/
EmptyCollectionComparisonExpression(AbstractExpression parent,
String identifier,
AbstractExpression expression) {
super(parent, identifier);
updateExpression(expression);
}
/**
* {@inheritDoc}
*/
public void accept(ExpressionVisitor visitor) {
visitor.visit(this);
}
/**
* {@inheritDoc}
*/
public void acceptChildren(ExpressionVisitor visitor) {
getExpression().accept(visitor);
}
/**
* {@inheritDoc}
*/
@Override
protected void addChildrenTo(Collection<Expression> children) {
children.add(getExpression());
}
/**
* {@inheritDoc}
*/
@Override
protected void addOrderedChildrenTo(List<Expression> children) {
// Expression
if (expression != null) {
children.add(expression);
}
if (hasExpression()) {
children.add(buildStringExpression(SPACE));
}
// 'IS'
children.add(buildStringExpression(IS));
if (hasSpaceAfterIs) {
children.add(buildStringExpression(SPACE));
}
// 'NOT'
if (notIdentifier != null) {
children.add(buildStringExpression(NOT));
}
children.add(buildStringExpression(SPACE));
// 'EMPTY'
children.add(buildStringExpression(EMPTY));
}
private StateFieldPathToCollectionValuedPathConverter buildConverter(AbstractExpression expression) {
return new StateFieldPathToCollectionValuedPathConverter(this, expression);
}
/**
* {@inheritDoc}
*/
@Override
public JPQLQueryBNF findQueryBNF(Expression expression) {
if ((this.expression != null) && this.expression.isAncestor(expression)) {
return getQueryBNF(CollectionValuedPathExpressionBNF.ID);
}
return super.findQueryBNF(expression);
}
/**
* Returns the actual <b>EMPTY</b> found in the string representation of the JPQL query, which
* has the actual case that was used.
*
* @return The <b>EMPTY</b> identifier that was actually parsed
*/
public String getActualEmptyIdentifier() {
return emptyIdentifier;
}
/**
* Returns the actual <b>IS</b> found in the string representation of the JPQL query, which has
* the actual case that was used.
*
* @return The <b>IS</b> identifier that was actually parsed, or an empty string if it was not
* parsed
*/
public String getActualIsIdentifier() {
return (isIdentifier != null) ? isIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* Returns the actual <b>NOT</b> found in the string representation of the JPQL query, which has
* the actual case that was used.
*
* @return The <b>NOT</b> identifier that was actually parsed, or an empty string if it was not
* parsed
*/
public String getActualNotIdentifier() {
return (notIdentifier != null) ? notIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* Returns the {@link Expression} that represents the collection-valued path expression if it was
* parsed.
*
* @return The expression that was parsed representing the collection valued path expression
*/
public Expression getExpression() {
if (expression == null) {
expression = buildNullExpression();
}
return expression;
}
/**
* Returns the identifier for this expression that may include <b>NOT</b> if it was parsed. The
* identifier <b>IS</b> should always be part of the identifier but it is possible it is not
* present when this expression is invalid.
*
* @return Either <b>IS NOT EMPTY</b>, <b>NOT EMPTY</b>, <b>IS EMPTY</b> or <b>EMPTY</b>
*/
public String getIdentifier() {
if ((isIdentifier != null) && (notIdentifier != null)) {
return IS_NOT_EMPTY;
}
if ((isIdentifier == null) && (notIdentifier != null)) {
return "NOT_EMPTY";
}
if (isIdentifier != null) {
return IS_EMPTY;
}
return EMPTY;
}
/**
* {@inheritDoc}
*/
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(EmptyCollectionComparisonExpressionBNF.ID);
}
/**
* Determines whether the expression was parsed.
*
* @return <code>true</code> if the expression was parsed; <code>false</code> otherwise
*/
public boolean hasExpression() {
return expression != null &&
!expression.isNull();
}
/**
* Determines whether the identifier <b>NOT</b> was part of the query.
*
* @return <code>true</code> if the identifier <b>NOT</b> was parsed; <code>false</code> otherwise
*/
public boolean hasNot() {
return notIdentifier != null;
}
/**
* Determines whether a whitespace was found after <b>IS</b>.
*
* @return <code>true</code> if there was a whitespace after <b>IS</b>; <code>false</code> otherwise
*/
public boolean hasSpaceAfterIs() {
return hasSpaceAfterIs;
}
/**
* {@inheritDoc}
*/
@Override
protected void parse(WordParser wordParser, boolean tolerant) {
String identifier = getText();
if (identifier != null) {
// 'IS'
isIdentifier = wordParser.moveForward(IS);
hasSpaceAfterIs = true;
wordParser.moveForward(1);
// 'NOT'
if (identifier == IS_NOT_EMPTY) {
notIdentifier = wordParser.moveForward(NOT);
wordParser.moveForward(1);
}
// 'EMPTY'
emptyIdentifier = wordParser.moveForward(EMPTY);
}
else {
// Parse 'IS'
if (wordParser.startsWithIdentifier(IS)) {
isIdentifier = wordParser.moveForward(IS);
hasSpaceAfterIs = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'NOT'
if (wordParser.startsWithIdentifier(NOT)) {
notIdentifier = wordParser.moveForward(NOT);
wordParser.skipLeadingWhitespace();
}
// Parse 'EMPTY'
emptyIdentifier = wordParser.moveForward(EMPTY);
}
}
/**
* {@inheritDoc}
*/
@Override
protected void toParsedText(StringBuilder writer, boolean actual) {
// Expression
if (expression != null) {
expression.toParsedText(writer, actual);
writer.append(SPACE);
}
// 'IS'
if (isIdentifier != null) {
writer.append(actual ? isIdentifier : IS);
}
if (hasSpaceAfterIs) {
writer.append(SPACE);
}
// 'NOT'
if (notIdentifier != null) {
writer.append(actual ? notIdentifier : NOT);
writer.append(SPACE);
}
// 'EMPTY'
writer.append(actual ? emptyIdentifier : EMPTY);
}
private void updateExpression(AbstractExpression expression) {
// Make sure a StateFieldPathExpression is converted into a
// CollectionValuedPathExpression
if (expression != null) {
StateFieldPathToCollectionValuedPathConverter converter = buildConverter(expression);
expression.accept(converter);
this.expression = converter.expression;
this.expression.setParent(this);
// The old expression needs to be parented in order to be removed from
// the parsing system
expression.setParent(this);
}
}
/**
* This visitor converts a {@link StateFieldPathExpression} into a {@link CollectionValuedPathExpression}.
* The parser only creates state field path expressions but this expression only supports a
* collection valued path expression.
*/
private static class StateFieldPathToCollectionValuedPathConverter extends AbstractExpressionVisitor {
private AbstractExpression expression;
private AbstractExpression parent;
/**
* Creates a new <code>StateFieldPathToCollectionValuedPathConverter</code>.
*
* @param parent The parent of the expression
* @param expression The expression that might need to be converted
*/
StateFieldPathToCollectionValuedPathConverter(AbstractExpression parent,
AbstractExpression expression) {
super();
this.parent = parent;
this.expression = expression;
}
/**
* {@inheritDoc}
*/
@Override
public void visit(StateFieldPathExpression expression) {
this.expression = new CollectionValuedPathExpression(parent, expression.getText());
}
}
}