rife2-template-renderers/lib/src/main/java/rife2/render/EncodeHtmlEntities.java

/*
 *  Copyright 2023 the original author or authors.
 *
 *  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
 *
 *       https://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 rife2.render;

import rife.template.Template;
import rife.template.ValueRenderer;

/**
 * <p>Encodes a template value to HTML decimal entities</p>
 *
 * <p>Usage:</p>
 *
 * <pre>
 *   &lt;!--v render:rife.render.EncodeHtmlEntities:valueId/--&gt;
 *   {{v render:rife.render.EncodeHtmlEntities:valueId}}
 * </pre>
 *
 * <p>For example {@code john@doe.com} would be encoded to:</p>
 *
 * <pre>&amp;#106;&amp;#111;&amp;#104;&amp;#110;&amp;#64;&amp;#100;&amp;#111;&amp;#101;&amp;#46;&amp;#99;&amp;#111;&amp;#109;</pre>
 *
 * @author <a href="https://erik.thauvin.net/">Erik C. Thauvin</a>
 * @since 1.0
 */
public class EncodeHtmlEntities implements ValueRenderer {
    /**
     * Converts a text string to HTML decimal entities.
     *
     * @param text the String to convert.
     * @return the converted string.
     */
    public static String toHtmlEntities(String text) {
        var buff = new StringBuilder(text.length() * 6);

        for (var i = 0; i < text.length(); i++) {
            buff.append("&#").append((int) text.charAt(i)).append(';');
        }

        return buff.toString();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String render(Template template, String valueId, String differentiator) {
        if (differentiator != null && !differentiator.isBlank() && template.hasValueId(differentiator)) {
            return toHtmlEntities(template.getValue(differentiator));
        } else {
            return "";
        }
    }
}