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

/*
 * Copyright (c) 2006, 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 java.util.ListIterator;
import org.eclipse.persistence.jpa.jpql.tools.spi.IEntity;
import org.eclipse.persistence.jpa.jpql.tools.spi.IManagedType;
import static org.eclipse.persistence.jpa.jpql.parser.Expression.*;

/**
 * An identification variable is a valid identifier declared in the <code><b>FROM</b></code> clause
 * of a query. All identification variables must be declared in the <code><b>FROM</b></code> clause.
 * Identification variables cannot be declared in other clauses. An identification variable must not
 * be a reserved identifier or have the same name as any entity in the same persistence unit:
 * Identification variables are case insensitive. An identification variable evaluates to a value of
 * the type of the expression used in declaring the variable.
 *
 * <div><p><b>BNF:</b> <code>identification_variable_declaration ::= range_variable_declaration { join | fetch_join }*</code></p></div>
 *
 * @see org.eclipse.persistence.jpa.jpql.parser.IdentificationVariableDeclaration IdentificationVariableDeclaration
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
public class IdentificationVariableDeclarationStateObject extends AbstractIdentificationVariableDeclarationStateObject {

    /**
     * Creates a new <code>IdentificationVariableDeclarationStateObject</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 IdentificationVariableDeclarationStateObject(AbstractFromClauseStateObject parent) {
        super(parent);
    }

    /**
     * Creates a new <code>IdentificationVariableDeclarationStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param entity The external form of the entity to add to the declaration list
     * @param identificationVariable The unique identifier identifying the abstract schema name
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public IdentificationVariableDeclarationStateObject(AbstractFromClauseStateObject parent,
                                                        IEntity entity,
                                                        String identificationVariable) {

        super(parent);
        getRangeVariableDeclaration().setDeclaration(entity, identificationVariable);
    }

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

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

    /**
     * Adds a new <code><b>INNER JOIN FETCH</b></code> expression to this declaration.
     *
     * @param path The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addInnerJoinFetch(String path) {
        return addJoinFetch(INNER_JOIN, path);
    }

    /**
     * Adds a new <code><b>JOIN FETCH</b></code> expression to this declaration.
     *
     * @param path The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addJoinFetch(String path) {
        return addJoinFetch(JOIN_FETCH, path);
    }

    /**
     * Adds a new <code><b>JOIN FETCH</b></code> expression to this declaration.
     *
     * @param joinFetchType One of the joining types: <code><b>LEFT JOIN FETCH</b></code>, <code><b>LEFT
     * OUTER JOIN FETCH</b></code>, <code><b>INNER JOIN FETCH</b></code> or <code><b>JOIN FETCH</b></code>
     * @param paths The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addJoinFetch(String joinFetchType,
                                        ListIterator<String> paths) {

        JoinStateObject stateObject = addJoinFetch(joinFetchType);
        stateObject.setJoinAssociationPaths(paths);
        addItem(stateObject);
        return stateObject;
    }

    /**
     * Adds a new <code><b>JOIN FETCH</b></code> expression to this declaration.
     *
     * @param joinFetchType One of the joining types: <code><b>LEFT JOIN FETCH</b></code>, <code><b>LEFT
     * OUTER JOIN FETCH</b></code>, <code><b>INNER JOIN FETCH</b></code> or <code><b>JOIN FETCH</b></code>
     * @param path The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addJoinFetch(String joinFetchType, String path) {
        JoinStateObject stateObject = new JoinStateObject(this, joinFetchType);
        stateObject.setJoinAssociationPath(path);
        addItem(stateObject);
        return stateObject;
    }

    /**
     * Adds a new <code><b>JOIN FETCH</b></code> expression to this declaration.
     *
     * @param joinFetchType One of the joining types: <code><b>LEFT JOIN FETCH</b></code>, <code><b>LEFT
     * OUTER JOIN FETCH</b></code>, <code><b>INNER JOIN FETCH</b></code> or <code><b>JOIN FETCH</b></code>
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addJoinFetchType(String joinFetchType) {
        JoinStateObject stateObject = new JoinStateObject(this, joinFetchType);
        addItem(stateObject);
        return stateObject;
    }

    /**
     * Adds a new <code><b>LEFT JOIN FETCH</b></code> expression to this declaration.
     *
     * @param path The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addLeftJoinFetch(String path) {
        return addJoinFetch(LEFT_JOIN_FETCH, path);
    }

    /**
     * Adds a new <code><b>LEFT OUTER JOIN FETCH</b></code> expression to this declaration.
     *
     * @param path The join association path expression
     * @return A new {@link JoinStateObject}
     */
    public JoinStateObject addLeftOuterJoinFetch(String path) {
        return addJoinFetch(LEFT_OUTER_JOIN_FETCH, path);
    }

    @Override
    protected AbstractRangeVariableDeclarationStateObject buildRangeVariableDeclarationStateObject() {
        return new RangeVariableDeclarationStateObject(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() {
        return getRootStateObject().getEntity();
    }

    /**
     * Returns the name of the entity for which it is used as the "root" of the declaration.
     *
     * @return The name of the entity
     */
    public String getEntityName() {
        return getRootStateObject().getText();
    }

    @Override
    public IManagedType getManagedType(StateObject stateObject) {

        if (getIdentificationVariableStateObject().isEquivalent(stateObject)) {
            return getEntity();
        }

        return null;
    }

    @Override
    public RangeVariableDeclarationStateObject getRangeVariableDeclaration() {
        return (RangeVariableDeclarationStateObject) super.getRangeVariableDeclaration();
    }

    @Override
    public AbstractSchemaNameStateObject getRootStateObject() {
        return (AbstractSchemaNameStateObject) super.getRootStateObject();
    }

    @Override
    protected String listName() {
        return JOINS_LIST;
    }

    /**
     * Sets the {@link IEntity} as the "root".
     *
     * @param entity The {@link IEntity} itself
     */
    public void setEntity(IEntity entity) {
        getRootStateObject().setEntity(entity);
    }

    /**
     * Sets the name of the abstract schema, which is the name of the entity.
     *
     * @param entityName The name of the entity
     */
    public void setEntityName(String entityName) {
        getRootStateObject().setText(entityName);
    }
}