/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.geronimo.system.configuration.condition;
import java.util.Map;
import org.apache.commons.jexl.Expression;
import org.apache.commons.jexl.ExpressionFactory;
import org.apache.commons.jexl.JexlContext;
import org.apache.commons.jexl.JexlHelper;
import org.apache.commons.jexl.resolver.FlatResolver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Parses expressions using <a href="http://jakarta.apache.org/commons/jexl/">Commons Jexl</a>.
*
* @version $Rev: 787153 $ $Date: 2009-06-22 14:58:02 +0800 (Mon, 22 Jun 2009) $
*/
public class JexlExpressionParser
{
private static final Logger log = LoggerFactory.getLogger(JexlExpressionParser.class);
protected JexlContext context;
public JexlExpressionParser(final Map vars) {
if (vars == null) {
throw new IllegalArgumentException("vars");
}
context = JexlHelper.createContext();
context.setVars(vars);
log.trace("Using variables: {}", context.getVars());
}
public JexlExpressionParser() {
this(System.getProperties());
}
public Map getVariables() {
return context.getVars();
}
public Object getVariable(final Object name) {
if (name == null) {
throw new IllegalArgumentException("name");
}
return getVariables().get(name);
}
public Object setVariable(final Object name, final Object value) {
if (name == null) {
throw new IllegalArgumentException("name");
}
return getVariables().put(name, value);
}
public Object unsetVariable(final Object name) {
if (name == null) {
throw new IllegalArgumentException("name");
}
return getVariables().remove(name);
}
public void addVariables(final Map map) {
if (map == null) {
throw new IllegalArgumentException("map");
}
getVariables().putAll(map);
}
public void setVariables(final Map map) {
if (map == null) {
throw new IllegalArgumentException("map");
}
context.setVars(map);
}
private FlatResolver resolver = new FlatResolver(true);
protected Expression createExpression(final String expression) throws Exception {
// assert expression != null;
Expression expr = ExpressionFactory.createExpression(expression);
expr.addPreResolver(resolver);
return expr;
}
public Object evaluate(final String expression) throws Exception {
if (expression == null) {
throw new IllegalArgumentException("expression");
}
log.trace("Evaluating expression: {}", expression);
Expression expr = createExpression(expression);
Object obj = expr.evaluate(context);
log.trace("Result: {}", obj);
return obj;
}
public String parse(final String input) {
if (input == null) {
throw new IllegalArgumentException("input");
}
log.trace("Parsing input: {}", input);
StringBuilder buff = new StringBuilder();
int cur = 0;
int prefixLoc;
int suffixLoc;
while (cur < input.length()) {
prefixLoc = input.indexOf("${", cur);
if (prefixLoc < 0) {
break;
}
suffixLoc = findBlockEnd(prefixLoc + 2, input);
if (suffixLoc < 0) {
throw new RuntimeException("Missing '}': " + input);
}
String expr = input.substring(prefixLoc + 2, suffixLoc);
buff.append(input.substring(cur, prefixLoc));
try {
buff.append(evaluate(expr));
}
catch (Exception e) {
throw new RuntimeException("Failed to evaluate: " + expr, e);
}
cur = suffixLoc + 1;
}
buff.append(input.substring(cur));
log.trace("Parsed result: {}", buff);
return buff.toString();
}
private int findBlockEnd(int pos, String input) {
int nested = 0;
while (pos < input.length()) {
char ch = input.charAt(pos);
if (ch == '{') {
nested++;
} else if (ch == '}') {
if (nested == 0) {
return pos;
} else {
nested--;
}
}
pos++;
}
return -1;
}
public String parse(final String input, final boolean trim) {
String output = parse(input);
if (trim && output != null) {
output = output.trim();
}
return output;
}
}