java/org/apache/jasper/runtime/JspFragmentHelper.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.jasper.runtime;

import jakarta.servlet.jsp.JspContext;
import jakarta.servlet.jsp.PageContext;
import jakarta.servlet.jsp.tagext.JspFragment;
import jakarta.servlet.jsp.tagext.JspTag;

/**
 * Helper class from which all Jsp Fragment helper classes extend. This class allows for the emulation of numerous
 * fragments within a single class, which in turn reduces the load on the class loader since there are potentially many
 * JspFragments in a single page.
 * <p>
 * The class also provides various utility methods for JspFragment implementations.
 */
public abstract class JspFragmentHelper extends JspFragment {

    /**
     * Discriminator value used to identify the specific fragment within a multi-fragment class.
     */
    protected final int discriminator;

    /**
     * The JSP context associated with this fragment.
     */
    protected final JspContext jspContext;

    /**
     * The page context associated with this fragment, cast from the JSP context.
     */
    protected final PageContext _jspx_page_context;

    /**
     * The parent tag that owns this fragment.
     */
    protected final JspTag parentTag;

    /**
     * Creates a new JspFragmentHelper instance.
     *
     * @param discriminator the fragment discriminator value
     * @param jspContext the JSP context for this fragment
     * @param parentTag the parent tag
     */
    public JspFragmentHelper(int discriminator, JspContext jspContext, JspTag parentTag) {
        this.discriminator = discriminator;
        this.jspContext = jspContext;
        if (jspContext instanceof PageContext) {
            _jspx_page_context = (PageContext) jspContext;
        } else {
            _jspx_page_context = null;
        }
        this.parentTag = parentTag;
    }

    @Override
    public JspContext getJspContext() {
        return this.jspContext;
    }

    /**
     * Returns the parent tag that owns this fragment.
     *
     * @return the parent tag
     */
    public JspTag getParentTag() {
        return this.parentTag;
    }

}