AbstractSingleEncapsulatedExpression.java

/*******************************************************************************
 * 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.Assert;
import org.eclipse.persistence.jpa.jpql.WordParser;

/**
 * This expression handles parsing a JPQL identifier followed by an expression encapsulated within
 * parenthesis.
 *
 * <div><b>BNF:</b> <code>expression ::= <identifier>(expression)</code><p></div>
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
@SuppressWarnings("nls")
public abstract class AbstractSingleEncapsulatedExpression extends AbstractEncapsulatedExpression {

    /**
     * The sub-expression encapsulated within parenthesis.
     */
    private AbstractExpression expression;

    /**
     * Creates a new <code>EncapsulatedExpression</code>.
     *
     * @param parent The parent of this expression
     * @param identifier The JPQL identifier that starts this expression
     */
    protected AbstractSingleEncapsulatedExpression(AbstractExpression parent, String identifier) {
        super(parent, identifier);
    }

    /**
     * {@inheritDoc}
     */
    public void acceptChildren(ExpressionVisitor visitor) {
        getExpression().accept(visitor);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected final void addChildrenTo(Collection<Expression> children) {
        children.add(getExpression());
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void addOrderedEncapsulatedExpressionTo(List<Expression> children) {
        if (expression != null) {
            children.add(expression);
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public JPQLQueryBNF findQueryBNF(Expression expression) {

        if ((expression != null) && expression.isAncestor(expression)) {
            return getQueryBNF(getEncapsulatedExpressionQueryBNFId());
        }

        return super.findQueryBNF(expression);
    }

    /**
     * Returns the BNF used to parse the encapsulated expression.
     *
     * @return The BNF used to parse the encapsulated expression
     */
    public abstract String getEncapsulatedExpressionQueryBNFId();

    /**
     * Returns the {@link Expression} that is encapsulated within parenthesis.
     *
     * @return The {@link Expression} that is encapsulated within parenthesis
     */
    public final Expression getExpression() {
        if (expression == null) {
            expression = buildNullExpression();
        }
        return expression;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean hasEncapsulatedExpression() {
        return hasExpression();
    }

    /**
     * Determines whether the encapsulated expression of the query was parsed.
     *
     * @return <code>true</code> if the encapsulated expression was parsed; <code>false</code> if it
     * was not parsed
     */
    public final boolean hasExpression() {
        return expression != null &&
              !expression.isNull();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void parseEncapsulatedExpression(WordParser wordParser,
                                               int whitespaceCount,
                                               boolean tolerant) {

        expression = parse(wordParser, getEncapsulatedExpressionQueryBNFId(), tolerant);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void removeEncapsulatedExpression() {
        expression = null;
    }

    /**
     * Manually sets the encapsulated {@link Expression} to become the given one.
     *
     * @param expression The new encapsulated {@link Expression}, which cannot be <code>null</code>
     * @exception NullPointerException The given {@link AbstractExpression} cannot be <code>null</code>
     */
    public final void setExpression(AbstractExpression expression) {
        Assert.isNotNull(expression, "The Expression cannot be null");
        this.expression = expression;
        this.expression.setParent(this);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void toParsedTextEncapsulatedExpression(StringBuilder writer, boolean actual) {
        if (expression != null) {
            expression.toParsedText(writer, actual);
        }
    }
}