001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.jxpath;
018
019 import java.util.ArrayList;
020 import java.util.HashMap;
021 import java.util.Iterator;
022 import java.util.List;
023 import java.util.Set;
024
025 /**
026 * An object that aggregates {@link Functions} objects into a group Functions
027 * object. Since {@link JXPathContext} can only register a single Functions
028 * object, FunctionLibrary should always be used to group all Functions objects
029 * that need to be registered.
030 *
031 * @author Dmitri Plotnikov
032 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
033 */
034 public class FunctionLibrary implements Functions {
035 private List allFunctions = new ArrayList();
036 private HashMap byNamespace = null;
037
038 /**
039 * Add functions to the library
040 * @param functions to add
041 */
042 public void addFunctions(Functions functions) {
043 allFunctions.add(functions);
044 byNamespace = null;
045 }
046
047 /**
048 * Remove functions from the library.
049 * @param functions to remove
050 */
051 public void removeFunctions(Functions functions) {
052 allFunctions.remove(functions);
053 byNamespace = null;
054 }
055
056 /**
057 * Returns a set containing all namespaces used by the aggregated
058 * Functions.
059 * @return Set<String>
060 */
061 public Set getUsedNamespaces() {
062 if (byNamespace == null) {
063 prepareCache();
064 }
065 return byNamespace.keySet();
066 }
067
068 /**
069 * Returns a Function, if any, for the specified namespace,
070 * name and parameter types.
071 * @param namespace function namespace
072 * @param name function name
073 * @param parameters parameters
074 * @return Function found
075 */
076 public Function getFunction(String namespace, String name,
077 Object[] parameters) {
078 if (byNamespace == null) {
079 prepareCache();
080 }
081 Object candidates = byNamespace.get(namespace);
082 if (candidates instanceof Functions) {
083 return ((Functions) candidates).getFunction(
084 namespace,
085 name,
086 parameters);
087 }
088 if (candidates instanceof List) {
089 List list = (List) candidates;
090 int count = list.size();
091 for (int i = 0; i < count; i++) {
092 Function function =
093 ((Functions) list.get(i)).getFunction(
094 namespace,
095 name,
096 parameters);
097 if (function != null) {
098 return function;
099 }
100 }
101 }
102 return null;
103 }
104
105 /**
106 * Prepare the cache.
107 */
108 private void prepareCache() {
109 byNamespace = new HashMap();
110 int count = allFunctions.size();
111 for (int i = 0; i < count; i++) {
112 Functions funcs = (Functions) allFunctions.get(i);
113 Set namespaces = funcs.getUsedNamespaces();
114 for (Iterator it = namespaces.iterator(); it.hasNext();) {
115 String ns = (String) it.next();
116 Object candidates = byNamespace.get(ns);
117 if (candidates == null) {
118 byNamespace.put(ns, funcs);
119 }
120 else if (candidates instanceof Functions) {
121 List lst = new ArrayList();
122 lst.add(candidates);
123 lst.add(funcs);
124 byNamespace.put(ns, lst);
125 }
126 else {
127 ((List) candidates).add(funcs);
128 }
129 }
130 }
131 }
132 }