/*

 * Copyright (c) 2010, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.javadoc.internal.doclets.toolkit;

import java.io.IOException;

import java.io.StringWriter;

import java.io.Writer;

import java.util.Objects;

/**

 * A class to create content for javadoc output pages.

 *

 *  <p><b>This is NOT part of any supported API.

 *  If you write code that depends on this, you do so at your own risk.

 *  This code and its internal interfaces are subject to change or

 *  deletion without notice.</b>

 *

 * @author Bhavesh Patel

 */

public abstract class Content {

    /**

     * Returns a string representation of the content.

     *

     * @return string representation of the content

     */

    @Override

    public String toString() {

        StringWriter out = new StringWriter();

        try {

            write(out, true);

        } catch (IOException e) {

            // cannot happen from StringWriter

        }

        return out.toString();

    }

    /**

     * Adds content to the existing content.

     *

     * @param content content that needs to be added

     */

    public abstract void addContent(Content content);

    /**

     * Adds a string content to the existing content.

     *

     * @param stringContent the string content to be added

     */

    public abstract void addContent(CharSequence stringContent);

    /**

     * Writes content to a writer.

     *

     */

    public abstract boolean write(Writer writer, boolean atNewline) throws IOException ;

    /**

     * Returns true if the content is empty.

     *

     * @return true if no content to be displayed else return false

     */

    public abstract boolean isEmpty();

    /**

     * Returns true if the content is valid.

     *

     * @return true if the content is valid else return false

     */

    public boolean isValid() {

        return !isEmpty();

    }

    /**

     * Return the number of characters of plain text content in this object

     * (optional operation.)

     * @return the number of characters of plain text content in this

     */

    public int charCount() {

        return 0;

    }

    /**

     * Checks for null values.

     *

     * @param t reference type to check for null values

     * @return the reference type if not null or else throws a null pointer exception

     */

    protected static <T> T nullCheck(T t) {

        return Objects.requireNonNull(t);

    }

}