jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/tools/model/query/AbstractSchemaNameStateObject.java

/*
 * Copyright (c) 2011, 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.tools.model.query;

import org.eclipse.persistence.jpa.jpql.parser.AbstractSchemaName;
import org.eclipse.persistence.jpa.jpql.tools.spi.IEntity;

/**
 * An abstract schema name designates the abstract schema type over which the query ranges.
 *
 * @see AbstractSchemaName
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
public class AbstractSchemaNameStateObject extends SimpleStateObject {

    /**
     * The actual {@link IEntity} is it was resolved.
     */
    private IEntity entity;

    /**
     * Creates a new <code>AbstractSchemaNameStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public AbstractSchemaNameStateObject(StateObject parent) {
        super(parent);
    }

    /**
     * Creates a new <code>AbstractSchemaNameStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param entity The {@link IEntity} itself
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public AbstractSchemaNameStateObject(StateObject parent, IEntity entity) {
        this(parent, entity.getName());
        this.entity = entity;
    }

    /**
     * Creates a new <code>AbstractSchemaNameStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param entityName The name of the entity
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public AbstractSchemaNameStateObject(StateObject parent, String entityName) {
        super(parent, entityName);
    }

    @Override
    public void accept(StateObjectVisitor visitor) {
        visitor.visit(this);
    }

    /**
     * Returns the actual external form representing the {@link IEntity}.
     *
     * @return The actual {@link IEntity} or <code>null</code> if no entity exists with the entity name
     */
    public IEntity getEntity() {
        if (entity == null) {
            resolveEntity();
        }
        return entity;
    }

    @Override
    public AbstractSchemaName getExpression() {
        return (AbstractSchemaName) super.getExpression();
    }

    /**
     * Returns the name of the abstract schema, which is the name of the entity.
     *
     * @return The name of the abstract schema, which is the name of the entity
     */
    @Override
    public String getText() {
        return super.getText();
    }

    /**
     * Determines whether the {@link IEntity} has been resolved.
     *
     * @return <code>true</code> if an entity exists with the abstract schema name in the managed
     * types provider; <code>false</code> otherwise
     */
    public boolean isEntityResolved() {
        return entity != null;
    }

    /**
     * Resolves the abstract schema name and retrieve the associated {@link IEntity}.
     */
    public void resolveEntity() {
        entity = getManagedTypeProvider().getEntityNamed(getText());
    }

    /**
     * Sets the actual {@link IEntity} and updates the abstract schema name.
     *
     * @param entity The new {@link IEntity}
     */
    public void setEntity(IEntity entity) {
        this.entity = entity;
        super.setText((entity != null) ? entity.getName() : null);
    }

    /**
     * Keeps a reference of the {@link AbstractSchemaName parsed object} object, which should only be
     * done when this object is instantiated during the conversion of a parsed JPQL query into
     * {@link StateObject StateObjects}.
     *
     * @param expression The {@link AbstractSchemaName parsed object} representing an abstract schema
     * name (entity name)
     */
    public void setExpression(AbstractSchemaName expression) {
        super.setExpression(expression);
    }

    /**
     * Sets the name of the abstract schema, which is the name of the entity.
     *
     * @param abstractSchemaName The name of the abstract schema, which is the name of the entity
     */
    @Override
    public void setText(String abstractSchemaName) {
        this.entity = null;
        super.setText(abstractSchemaName);
    }
}