org.apache.commons.jxpath.ClassFunctions Maven / Gradle / Ivy
/*
* 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.commons.jxpath;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.Set;
import org.apache.commons.jxpath.functions.ConstructorFunction;
import org.apache.commons.jxpath.functions.MethodFunction;
import org.apache.commons.jxpath.util.MethodLookupUtils;
/**
* Extension functions provided by a Java class.
*
* Let's say we declared a ClassFunction like this:
*
* new ClassFunctions(Integer.class, "int")
*
*
* We can now use XPaths like:
*
* "int:new(3)"- Equivalent to
new Integer(3)
* "int:getInteger('foo')"- Equivalent to
Integer.getInteger("foo")
* "int:floatValue(int:new(4))"- Equivalent to
new Integer(4).floatValue()
*
*
*
* If the first argument of a method is {@link ExpressionContext}, the
* expression context in which the function is evaluated is passed to
* the method.
*
* @author Dmitri Plotnikov
* @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
*/
public class ClassFunctions implements Functions {
private static final Object[] EMPTY_ARRAY = new Object[0];
private Class functionClass;
private String namespace;
/**
* Create a new ClassFunctions.
* @param functionClass Class providing the functions
* @param namespace assigned ns
*/
public ClassFunctions(Class functionClass, String namespace) {
this.functionClass = functionClass;
this.namespace = namespace;
}
/**
* Returns a set of one namespace - the one specified in the constructor.
*
* @return a singleton
*/
public Set getUsedNamespaces() {
return Collections.singleton(namespace);
}
/**
* Returns a {@link Function}, if any, for the specified namespace,
* name and parameter types.
*
* @param namespace if it is not the namespace specified in the constructor,
* the method returns null
* @param name is a function name or "new" for a constructor.
* @param parameters Object[] of parameters
*
* @return a MethodFunction, a ConstructorFunction or null if there is no
* such function.
*/
public Function getFunction(
String namespace,
String name,
Object[] parameters) {
if (namespace == null) {
if (this.namespace != null) {
return null;
}
}
else if (!namespace.equals(this.namespace)) {
return null;
}
if (parameters == null) {
parameters = EMPTY_ARRAY;
}
if (name.equals("new")) {
Constructor constructor =
MethodLookupUtils.lookupConstructor(functionClass, parameters);
if (constructor != null) {
return new ConstructorFunction(constructor);
}
}
else {
Method method = MethodLookupUtils.
lookupStaticMethod(functionClass, name, parameters);
if (method != null) {
return new MethodFunction(method);
}
method = MethodLookupUtils.
lookupMethod(functionClass, name, parameters);
if (method != null) {
return new MethodFunction(method);
}
}
return null;
}
}