com.saxonica.xqj.Closable Maven / Gradle / Ivy

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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package com.saxonica.xqj;

import javax.xml.xquery.XQException;

/**
 * This class represents the common ability of many XQJ classes to be closed. Note that closing an object
 * serves no useful purpose in the Saxon implementation; this complex machinery is provided merely to satisfy
 * the XQJ interface, which is designed to accommodate a client-server implementation.
 */
public abstract class Closable {

    /*@Nullable*/ private Closable container = null;
    private boolean closed = false;

    /**
     * Set the container of this closable object. Closing the container causes this object to be
     * treated as closed itself
     *
     * @param container the container of this closable object
     */

    public final void setClosableContainer(Closable container) {
        this.container = container;
    }

    /**
     * Close this object
     */

    public final void close() {
        closed = true;
    }

    /**
     * Ask whether this object has been closed.
     *
     * @return true if either the object itself or its container has been closed
     */

    public final boolean isClosed() {
        if (container != null && container.isClosed()) {
            close();
        }
        return closed;
    }

    /**
     * Check whether this object has been closed (either directly, or by closing its container)
     *
     * @throws XQException if the object has been closed
     */

    final void checkNotClosed() throws XQException {
        if (isClosed()) {
            throw new XQException("The XQJ object has been closed");
        }
    }
}