LazyElement.java

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 * as indicated by the @author tags. See the copyright.txt file in the
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 *
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 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
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 *
 * This software is distributed in the hope that it will be useful,
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
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 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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 */
package org.jboss.gwt.elemento.core;

import elemental2.dom.HTMLElement;

/**
 * Convenience class to support lazy element creation. The bulk of a LazyElement is not instantiated until {@link
 * #asElement()} is called.
 *
 * @author Harald Pehl
 */
public abstract class LazyElement implements IsElement {

    private HTMLElement element;

    /**
     * Creates and returns the element on demand by calling {@link #createElement()} or just returns the previously
     * created element.
     */
    @Override
    public HTMLElement asElement() {
        if (element == null) {
            element = createElement();
        }
        return element;
    }

    /**
     * Create the element contained within the {@link LazyElement}.
     *
     * @return the lazy element
     */
    protected abstract HTMLElement createElement();

    /**
     * @return whether the element was already created
     */
    protected boolean initialized() {
        return element != null;
    }
}