/*
* =============================================================================
*
* Copyright (c) 2011-2014, 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.expression;
import org.thymeleaf.Configuration;
import org.thymeleaf.exceptions.TemplateProcessingException;
/**
* <p>
* Utility class for the easy obtention of objects relevant to the parsing and execution of Thymeleaf
* Standard Expressions.
* </p>
*
* @author Daniel Fernández
*
* @since 2.1.0
*
*/
public final class StandardExpressions {
/**
* Name used for registering the <i>Standard Variable Expression Evaluator</i> object as an
* <i>execution attribute</i> at the Standard Dialects.
*/
public static final String STANDARD_VARIABLE_EXPRESSION_EVALUATOR_ATTRIBUTE_NAME = "StandardVariableExpressionEvaluator";
/**
* Name used for registering the <i>Standard Expression Parser</i> object as an
* <i>execution attribute</i> at the Standard Dialects.
*/
public static final String STANDARD_EXPRESSION_PARSER_ATTRIBUTE_NAME = "StandardExpressionParser";
/**
* Name used for registering the <i>Standard Conversion Service</i> object as an
* <i>execution attribute</i> at the Standard Dialects.
*/
public static final String STANDARD_CONVERSION_SERVICE_ATTRIBUTE_NAME = "StandardConversionService";
private StandardExpressions() {
super();
}
/**
* <p>
* Obtain the expression parser (implementation of {@link IStandardExpressionParser}) registered by
* the Standard Dialect that is being currently used.
* </p>
*
* @param configuration the configuration object for the current template execution environment.
* @return the parser object.
*/
public static IStandardExpressionParser getExpressionParser(final Configuration configuration) {
final Object parser =
configuration.getExecutionAttributes().get(STANDARD_EXPRESSION_PARSER_ATTRIBUTE_NAME);
if (parser == null || (!(parser instanceof IStandardExpressionParser))) {
throw new TemplateProcessingException(
"No Standard Expression Parser has been registered as an execution argument. " +
"This is a requirement for using Standard Expressions, and might happen " +
"if neither the Standard or the SpringStandard dialects have " +
"been added to the Template Engine and none of the specified dialects registers an " +
"attribute of type " + IStandardExpressionParser.class.getName() + " with name " +
"\"" + STANDARD_EXPRESSION_PARSER_ATTRIBUTE_NAME + "\"");
}
return (IStandardExpressionParser) parser;
}
/**
* <p>
* Obtain the variable expression evaluator (implementation of {@link IStandardVariableExpressionEvaluator})
* registered by the Standard Dialect that is being currently used.
* </p>
* <p>
* Normally, there should be no need to obtain this object from the developers' code (only internally from
* {@link IStandardExpression} implementations).
* </p>
*
* @param configuration the configuration object for the current template execution environment.
* @return the variable expression evaluator object.
*/
public static IStandardVariableExpressionEvaluator getVariableExpressionEvaluator(final Configuration configuration) {
final Object expressionEvaluator =
configuration.getExecutionAttributes().get(STANDARD_VARIABLE_EXPRESSION_EVALUATOR_ATTRIBUTE_NAME);
if (expressionEvaluator == null || (!(expressionEvaluator instanceof IStandardVariableExpressionEvaluator))) {
throw new TemplateProcessingException(
"No Standard Variable Expression Evaluator has been registered as an execution argument. " +
"This is a requirement for using Standard Expressions, and might happen " +
"if neither the Standard or the SpringStandard dialects have " +
"been added to the Template Engine and none of the specified dialects registers an " +
"attribute of type " + IStandardVariableExpressionEvaluator.class.getName() + " with name " +
"\"" + STANDARD_VARIABLE_EXPRESSION_EVALUATOR_ATTRIBUTE_NAME + "\"");
}
return (IStandardVariableExpressionEvaluator) expressionEvaluator;
}
/**
* <p>
* Obtain the conversion service (implementation of {@link IStandardConversionService}) registered by
* the Standard Dialect that is being currently used.
* </p>
*
* @param configuration the configuration object for the current template execution environment.
* @return the conversion service object.
*/
public static IStandardConversionService getConversionService(final Configuration configuration) {
final Object conversionService =
configuration.getExecutionAttributes().get(STANDARD_CONVERSION_SERVICE_ATTRIBUTE_NAME);
if (conversionService == null || (!(conversionService instanceof IStandardConversionService))) {
throw new TemplateProcessingException(
"No Standard Conversion Service has been registered as an execution argument. " +
"This is a requirement for using Standard Expressions, and might happen " +
"if neither the Standard or the SpringStandard dialects have " +
"been added to the Template Engine and none of the specified dialects registers an " +
"attribute of type " + IStandardConversionService.class.getName() + " with name " +
"\"" + STANDARD_CONVERSION_SERVICE_ATTRIBUTE_NAME + "\"");
}
return (IStandardConversionService) conversionService;
}
}