jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/tools/model/query/ConcatExpressionStateObject.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 java.util.List;
import org.eclipse.persistence.jpa.jpql.parser.ConcatExpression;
import static org.eclipse.persistence.jpa.jpql.parser.AbstractExpression.*;

/**
 * The <code><b>CONCAT</b></code> function returns a string that is a concatenation of its arguments.
 * <p>
 * JPA 1.0:
 * <div><p><b>BNF:</b> <code>expression ::= CONCAT(string_primary, string_primary)</code></p></div>
 * JPA 2.0
 * <div><p><b>BNF:</b> <code>expression ::= CONCAT(string_primary, string_primary {, string_primary}*)</code></p></div>
 *
 * @see ConcatExpression
 *
 * @version 2.4
 * @since 2.4
 * @author Pascal Filion
 */
@SuppressWarnings({"nls", "unused"}) // unused used for the import statement: see bug 330740
public class ConcatExpressionStateObject extends AbstractListHolderStateObject<StateObject> {

    /**
     * Notifies the content of the list of {@link StateObject} representing the string primaries
     * has changed.
     */
    public static final String STRING_PRIMARY_STATE_OBJECT_LIST = "stringPrimary";

    /**
     * Creates a new <code>ConcatExpressionStateObject</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 ConcatExpressionStateObject(StateObject parent) {
        super(parent);
    }

    /**
     * Creates a new <code>ConcatExpressionStateObject</code>.
     *
     * @param stateObjects The list of {@link StateObject} representing the encapsulated expressions
     */
    public ConcatExpressionStateObject(StateObject parent, List<? extends StateObject> stateObjects) {
        super(parent, stateObjects);
    }

    /**
     * Creates a new <code>ConcatExpressionStateObject</code>.
     *
     * @param parent The parent of this state object, which cannot be <code>null</code>
     * @param stateObjects The list of {@link StateObject} representing the encapsulated expressions
     * @exception NullPointerException The given parent cannot be <code>null</code>
     */
    public ConcatExpressionStateObject(StateObject parent, StateObject... stateObjects) {
        super(parent, stateObjects);
    }

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

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

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

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

    /**
     * Keeps a reference of the {@link ConcatExpression 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 ConcatExpression parsed object} representing a <code><b>CONCAT</b></code>
     * expression
     */
    public void setExpression(ConcatExpression expression) {
        super.setExpression(expression);
    }

    @Override
    protected void toTextInternal(Appendable writer) throws IOException {
        writer.append(CONCAT);
        writer.append(LEFT_PARENTHESIS);
        toStringItems(writer, true);
        writer.append(RIGHT_PARENTHESIS);
    }
}