src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/markup/FixedStringContent.java

/*
 * 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.formats.html.markup;

import java.io.IOException;
import java.io.Writer;

import jdk.javadoc.internal.doclets.toolkit.Content;
import jdk.javadoc.internal.doclets.toolkit.util.DocletConstants;

/**
 * Class for containing fixed string content for HTML tags of javadoc output.
 *
 *  <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>
 */
public class FixedStringContent extends Content {
    private final String string;

    /**
     * Constructor to construct FixedStringContent object.
     *
     * @param content content for the object
     */
    public FixedStringContent(CharSequence content) {
        string = needEscape(content)
                ? escape(content)
                : content.toString();
    }

    /**
     * This method is not supported by the class.
     *
     * @param content content that needs to be added
     * @throws UnsupportedOperationException always
     */
    @Override
    public void addContent(Content content) {
        throw new UnsupportedOperationException();
    }

    /**
     * Adds content for the StringContent object.  The method escapes
     * HTML characters for the string content that is added.
     *
     * @param strContent string content to be added
     * @throws UnsupportedOperationException always
     */
    @Override
    public void addContent(CharSequence strContent) {
        throw new UnsupportedOperationException();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean isEmpty() {
        return string.isEmpty();
    }

    @Override
    public int charCount() {
        return RawHtml.charCount(string);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        return string;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean write(Writer out, boolean atNewline) throws IOException {
        out.write(string);
        return string.endsWith(DocletConstants.NL);
    }

    private boolean needEscape(CharSequence cs) {
        for (int i = 0; i < cs.length(); i++) {
            switch (cs.charAt(i)) {
                case '<':
                case '>':
                case '&':
                    return true;
            }
        }
        return false;
    }
    private String escape(CharSequence s) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            switch (ch) {
                case '<': sb.append("&lt;");  break;
                case '>': sb.append("&gt;");  break;
                case '&': sb.append("&amp;"); break;
                default:  sb.append(ch);      break;
            }
        }
        return sb.toString();
    }

}