com.day.cq.wcm.foundation.ELEvaluator Maven / Gradle / Ivy
/*
* Copyright 1997-2009 Day Management AG
* Barfuesserplatz 6, 4001 Basel, Switzerland
* All Rights Reserved.
*
* This software is the confidential and proprietary information of
* Day Management AG, ("Confidential Information"). You shall not
* disclose such Confidential Information and shall use it only in
* accordance with the terms of the license agreement you entered into
* with Day.
*/
package com.day.cq.wcm.foundation;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ELException;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.VariableResolver;
import org.apache.sling.api.SlingHttpServletRequest;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* ELEvaluator implements an expression language evaluator based on
* {@link ExpressionEvaluator}.
*/
public class ELEvaluator {
/**
* The logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(ELEvaluator.class);
/**
* Evaluates the given expression. If an error occurs while evaluating the
* expression, then the expression is returned as is and the error is logged
* as warning.
*
* @param expr the expression.
* @param request the current request.
* @param pageContext the current page context.
* @return the evaluated expression.
*/
public static String evaluate(String expr,
SlingHttpServletRequest request,
final PageContext pageContext) {
ExpressionEvaluator exprEval = pageContext.getExpressionEvaluator();
try {
return (String) exprEval.evaluate(expr, String.class, new VariableResolver() {
private final VariableResolver base = pageContext.getVariableResolver();
public Object resolveVariable(String name) throws ELException {
Object value = base.resolveVariable(name);
if (value == null) {
if (name.equals("profile")) {
log.warn("Error while evaluating expression: profile variable is not supported");
}
}
return value;
}
}, null);
} catch (ELException e) {
log.warn("Error while evaluating expression: {}", expr, e);
}
return expr;
}
}