jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/tools/model/query/OrderByClauseStateObject.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 java.io.IOException;
import org.eclipse.persistence.jpa.jpql.parser.InternalOrderByItemBNF;
import org.eclipse.persistence.jpa.jpql.parser.OrderByClause;
import org.eclipse.persistence.jpa.jpql.parser.OrderByItem.Ordering;
import org.eclipse.persistence.jpa.jpql.parser.OrderByItemBNF;
import static org.eclipse.persistence.jpa.jpql.parser.AbstractExpression.*;

/**
 * The <code><b>ORDER BY</b></code> clause allows the objects or values that are returned by the
 * query to be ordered.
 *
 * <div><p><b>BNF:</b> <code>orderby_clause ::= <b>ORDER BY</b> {@link OrderByItemStateObject orderby_item} {, {@link OrderByItemStateObject orderby_item}}*</code></p></div>
 *
 * @see org.eclipse.persistence.jpa.jpql.parser.OrderByClause OrderByClause
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
@SuppressWarnings({"nls", "unused"}) // unused used for the import statement: see bug 330740
public class OrderByClauseStateObject extends AbstractListHolderStateObject<OrderByItemStateObject> {

    /**
     * Notify the list of {@link StateObject StateObjects} representing the <code><b>ORDER BY</b></code>
     * items.
     */
    public static final String ORDER_BY_ITEMS_LIST = "orderByItems";

    /**
     * Creates a new <code>OrderByClauseStateObject</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 OrderByClauseStateObject(SelectStatementStateObject parent) {
        super(parent);
    }

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

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItem() {
        return addItem(Ordering.DEFAULT);
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @param ordering The ascending order
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItem(Ordering ordering) {
        OrderByItemStateObject updateItem = new OrderByItemStateObject(this, ordering);
        addItem(updateItem);
        return updateItem;
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItem(String... paths) {
        return addOrderByItem(paths, Ordering.DEFAULT);
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @param variable The identification variable or the result variable
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItem(String variable) {
        return addItem(variable, Ordering.DEFAULT);
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @param path The identification variable or the result variable
     * @param ordering The ascending order
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItem(String path, Ordering ordering) {
        OrderByItemStateObject orderByItem = addItem(ordering);
        orderByItem.setStateObject(buildStateObject(path, InternalOrderByItemBNF.ID));
        return orderByItem;
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause with <code><b>ASC</b></code>.
     *
     * @param variable The identification variable or the result variable
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItemAsc(String variable) {
        return addItem(variable, Ordering.ASC);
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause with <code><b>DESC</b></code>.
     *
     * @param variable The identification variable or the result variable
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addItemDesc(String variable) {
        return addItem(variable, Ordering.DESC);
    }

    /**
     * Adds a new <code><b>ORDER BY</b></code> item to this clause.
     *
     * @param paths The paths or the item
     * @param ordering The ascending order
     * @return The newly added {@link OrderByItemStateObject}
     */
    public OrderByItemStateObject addOrderByItem(String[] paths, Ordering ordering) {

        StateFieldPathExpressionStateObject stateField = new StateFieldPathExpressionStateObject(this);
        stateField.setPaths(paths);

        OrderByItemStateObject updateItem = new OrderByItemStateObject(this, stateField, ordering);
        addItem(updateItem);
        return updateItem;
    }

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

    @Override
    public SelectStatementStateObject getParent() {
        return (SelectStatementStateObject) super.getParent();
    }

    @Override
    public boolean isEquivalent(StateObject stateObject) {
        return super.isEquivalent(stateObject) &&
               areChildrenEquivalent((OrderByClauseStateObject) stateObject);
    }

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

    /**
     * Parses the given JPQL fragment, which represents either a single or many ordering items, the
     * fragment will be parsed and converted into {@link OrderByItemStateObject}.
     *
     * @param jpqlFragment The portion of the query to parse
     */
    public void parse(String jpqlFragment) {
        // Note: No need to add the items here, they are automatically added by the builder
        buildStateObjects(jpqlFragment, OrderByItemBNF.ID);
    }

    /**
     * Keeps a reference of the {@link OrderByClause 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 OrderByClause parsed object} representing an <code><b>ORDER
     * BY</b></code> clause
     */
    public void setExpression(OrderByClause expression) {
        super.setExpression(expression);
    }

    @Override
    protected void toTextInternal(Appendable writer) throws IOException {
        writer.append(ORDER_BY);
        if (hasItems()) {
            writer.append(SPACE);
            toStringItems(writer, true);
        }
    }
}