org.jboss.elemento.LazyElement Maven / Gradle / Ivy

/*
 * Copyright 2015-2016 Red Hat, Inc, and individual contributors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jboss.elemento;

import elemental2.dom.HTMLElement;

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

    private E element;

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

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

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