/*
* Copyright 2012, Emanuel Rabina (http://www.ultraq.net.nz/)
*
* 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 nz.net.ultraq.thymeleaf.decorator;
import static nz.net.ultraq.thymeleaf.LayoutUtilities.HTML_ELEMENT_TITLE;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.thymeleaf.Arguments;
import org.thymeleaf.Configuration;
import org.thymeleaf.dom.Element;
import org.thymeleaf.dom.Text;
import org.thymeleaf.exceptions.TemplateProcessingException;
import org.thymeleaf.processor.ProcessorResult;
import org.thymeleaf.processor.attr.AbstractAttrProcessor;
import org.thymeleaf.standard.expression.IStandardExpressionParser;
import org.thymeleaf.standard.expression.StandardExpressions;
import org.thymeleaf.util.StringUtils;
/**
* Allows for greater control of the resulting <title> element by
* specifying a pattern with some special tokens. This can be used to extend
* the decorator's title with the content's one, instead of simply overriding
* it.
*
* @author Emanuel Rabina
*/
public class TitlePatternProcessor extends AbstractAttrProcessor {
private static final Logger logger = LoggerFactory.getLogger(TitlePatternProcessor.class);
private static final String PARAM_TITLE_DECORATOR = "$DECORATOR_TITLE";
private static final String PARAM_TITLE_CONTENT = "$CONTENT_TITLE";
public static final String PROCESSOR_NAME_TITLEPATTERN = "title-pattern";
public static final String DECORATOR_TITLE = "title-pattern::decorator-title";
public static final String CONTENT_TITLE = "title-pattern::content-title";
/**
* Constructor, sets this processor to work on the 'title-pattern' attribute.
*/
public TitlePatternProcessor() {
super(PROCESSOR_NAME_TITLEPATTERN);
}
/**
* {@inheritDoc}
*/
@Override
public int getPrecedence() {
return 1;
}
/**
* {@inheritDoc}
*/
@Override
protected ProcessorResult processAttribute(Arguments arguments, Element element, String attributeName) {
// Ensure this attribute is only on the <title> element
if (!element.getNormalizedName().equals(HTML_ELEMENT_TITLE)) {
logger.error("layout:title-pattern attribute should only appear in a <title> element");
throw new IllegalArgumentException("layout:title-pattern attribute should only appear in a <title> element");
}
Configuration configuration = arguments.getConfiguration();
IStandardExpressionParser parser = StandardExpressions.getExpressionParser(configuration);
// Process the decorator and content title parts
String decoratortitle = processTitle((String)element.getNodeProperty(DECORATOR_TITLE),
arguments, configuration, parser);
String contenttitle = processTitle((String)element.getNodeProperty(CONTENT_TITLE),
arguments, configuration, parser);
// Replace the <title> text with an expanded title pattern expression,
// only using the pattern if both the decorator and content have a title.
String titlepattern = element.getAttributeValue(attributeName);
String title =
decoratortitle != null ? contenttitle != null ?
titlepattern
.replace(PARAM_TITLE_DECORATOR, decoratortitle)
.replace(PARAM_TITLE_CONTENT, contenttitle) :
decoratortitle :
contenttitle != null ? contenttitle : "";
element.clearChildren();
element.addChild(new Text(title));
element.removeAttribute(attributeName);
return ProcessorResult.OK;
}
/**
* Process a title part, executing expressions if it contains any.
*
* @param title
* @param arguments
* @param configuration
* @param parser
* @return The result of executing <tt>title</tt> if it contained any
* expressions, or <tt>null</tt> if the title resolved to an empty
* string or whitespace.
*/
private static String processTitle(String title, Arguments arguments,
Configuration configuration, IStandardExpressionParser parser) {
String titlevalue;
try {
titlevalue = title == null ? null :
parser.parseExpression(configuration, arguments, title)
.execute(configuration, arguments)
.toString();
}
catch (TemplateProcessingException ex) {
titlevalue = title;
}
titlevalue = StringUtils.isEmptyOrWhitespace(titlevalue) ? null : titlevalue.trim();
return titlevalue;
}
}