/*
* 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.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
* An object that aggregates {@link Functions} objects into a group Functions
* object. Since {@link JXPathContext} can only register a single Functions
* object, FunctionLibrary should always be used to group all Functions objects
* that need to be registered.
*
* @author Dmitri Plotnikov
* @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
*/
public class FunctionLibrary implements Functions {
private List allFunctions = new ArrayList();
private HashMap byNamespace = null;
/**
* Add functions to the library
* @param functions to add
*/
public void addFunctions(Functions functions) {
allFunctions.add(functions);
byNamespace = null;
}
/**
* Remove functions from the library.
* @param functions to remove
*/
public void removeFunctions(Functions functions) {
allFunctions.remove(functions);
byNamespace = null;
}
/**
* Returns a set containing all namespaces used by the aggregated
* Functions.
* @return Set<String>
*/
public Set getUsedNamespaces() {
if (byNamespace == null) {
prepareCache();
}
return byNamespace.keySet();
}
/**
* Returns a Function, if any, for the specified namespace,
* name and parameter types.
* @param namespace function namespace
* @param name function name
* @param parameters parameters
* @return Function found
*/
public Function getFunction(String namespace, String name,
Object[] parameters) {
if (byNamespace == null) {
prepareCache();
}
Object candidates = byNamespace.get(namespace);
if (candidates instanceof Functions) {
return ((Functions) candidates).getFunction(
namespace,
name,
parameters);
}
if (candidates instanceof List) {
List list = (List) candidates;
int count = list.size();
for (int i = 0; i < count; i++) {
Function function =
((Functions) list.get(i)).getFunction(
namespace,
name,
parameters);
if (function != null) {
return function;
}
}
}
return null;
}
/**
* Prepare the cache.
*/
private void prepareCache() {
byNamespace = new HashMap();
int count = allFunctions.size();
for (int i = 0; i < count; i++) {
Functions funcs = (Functions) allFunctions.get(i);
Set namespaces = funcs.getUsedNamespaces();
for (Iterator it = namespaces.iterator(); it.hasNext();) {
String ns = (String) it.next();
Object candidates = byNamespace.get(ns);
if (candidates == null) {
byNamespace.put(ns, funcs);
}
else if (candidates instanceof Functions) {
List lst = new ArrayList();
lst.add(candidates);
lst.add(funcs);
byNamespace.put(ns, lst);
}
else {
((List) candidates).add(funcs);
}
}
}
}
}
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