StandardTextTagProcessor.java

/*
 * =============================================================================
 * 
 *   Copyright (c) 2011-2016, The THYMELEAF team (http://www.thymeleaf.org)
 * 
 *   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.thymeleaf.standard.processor;

import org.thymeleaf.context.ITemplateContext;
import org.thymeleaf.engine.AttributeName;
import org.thymeleaf.exceptions.TemplateProcessingException;
import org.thymeleaf.model.IProcessableElementTag;
import org.thymeleaf.processor.element.IElementTagStructureHandler;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.util.LazyEscapingCharSequence;
import org.unbescape.html.HtmlEscape;
import org.unbescape.xml.XmlEscape;

/**
 *
 * @author Daniel Fernández
 *
 * @since 3.0.0
 *
 */
public final class StandardTextTagProcessor extends AbstractStandardExpressionAttributeTagProcessor {

    public static final int PRECEDENCE = 1300;
    public static final String ATTR_NAME = "text";


    public StandardTextTagProcessor(final TemplateMode templateMode, final String dialectPrefix) {
        super(templateMode, dialectPrefix, ATTR_NAME, PRECEDENCE, true);
    }



    @Override
    protected void doProcess(
            final ITemplateContext context,
            final IProcessableElementTag tag,
            final AttributeName attributeName, final String attributeValue,
            final Object expressionResult,
            final IElementTagStructureHandler structureHandler) {

        final TemplateMode templateMode = getTemplateMode();

        /*
         * Depending on the template mode and the length of the text to be output escaped, we will try to opt for
         * the most resource-efficient alternative.
         *
         *    * If we are outputting RAW, there is no escape to do, just pass through.
         *    * If we are outputting HTML, XML or TEXT we know output will be textual (result of calling .toString() on
         *      the expression result), and therefore we can decide between an immediate vs lazy escaping alternative
         *      depending on size. We will perform lazy escaping, writing directly to output Writer, if length > 100.
         *    * If we are outputting JAVASCRIPT or CSS, we will always pass the expression result unchanged to a lazy
         *      escape processor, so that whatever the JS/CSS serializer wants to do, it does it directly on the
         *      output Writer and the entire results are never really needed in memory.
         */

        final CharSequence text;

        if (templateMode != TemplateMode.JAVASCRIPT && templateMode != TemplateMode.CSS) {

            final String input = (expressionResult == null? "" : expressionResult.toString());

            if (templateMode == TemplateMode.RAW) {
                // RAW -> just output

                text = input;

            } else {

                if (input.length() > 100) {
                    // Might be a large text -> Lazy escaping on the output Writer
                    text = new LazyEscapingCharSequence(context.getConfiguration(), templateMode, input);
                } else {
                    // Not large -> better use a bit more of memory, but be faster
                    text = produceEscapedOutput(templateMode, input);
                }

            }

        } else {
            // JavaScript and CSS serializers always work directly on the output Writer, no need to store the entire
            // serialized contents in memory (unless the Writer itself wants to do so).

            text = new LazyEscapingCharSequence(context.getConfiguration(), templateMode, expressionResult);

        }

        // Report the result to the engine, whichever the type of process we have applied
        structureHandler.setBody(text, false);

    }


    private static String produceEscapedOutput(final TemplateMode templateMode, final String input) {

        switch (templateMode) {

            case TEXT:
                // fall-through
            case HTML:
                return HtmlEscape.escapeHtml4Xml(input);
            case XML:
                return XmlEscape.escapeXml10(input);
            default:
                throw new TemplateProcessingException(
                        "Unrecognized template mode " + templateMode + ". Cannot produce escaped output for " +
                        "this template mode.");
        }

    }


}