1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.jxpath;
18
19 import java.util.ArrayList;
20 import java.util.HashMap;
21 import java.util.Iterator;
22 import java.util.List;
23 import java.util.Map;
24 import java.util.Set;
25
26 /**
27 * An object that aggregates {@link Functions} objects into a group Functions
28 * object. Since {@link JXPathContext} can only register a single Functions
29 * object, FunctionLibrary should always be used to group all Functions objects
30 * that need to be registered.
31 *
32 * @author Dmitri Plotnikov
33 * @version $Revision: 1234255 $ $Date: 2012-01-21 04:11:46 +0100 (Sa, 21 Jan 2012) $
34 */
35 public class FunctionLibrary implements Functions {
36 private final List allFunctions = new ArrayList();
37 private Map byNamespace;
38
39 /**
40 * Add functions to the library
41 * @param functions to add
42 */
43 public void addFunctions(Functions functions) {
44 allFunctions.add(functions);
45 synchronized (this) {
46 byNamespace = null;
47 }
48 }
49
50 /**
51 * Remove functions from the library.
52 * @param functions to remove
53 */
54 public void removeFunctions(Functions functions) {
55 allFunctions.remove(functions);
56 synchronized (this) {
57 byNamespace = null;
58 }
59 }
60
61 /**
62 * Returns a set containing all namespaces used by the aggregated
63 * Functions.
64 * @return Set<String>
65 */
66 public Set getUsedNamespaces() {
67 return functionCache().keySet();
68 }
69
70 /**
71 * Returns a Function, if any, for the specified namespace,
72 * name and parameter types.
73 * @param namespace function namespace
74 * @param name function name
75 * @param parameters parameters
76 * @return Function found
77 */
78 public Function getFunction(String namespace, String name,
79 Object[] parameters) {
80 Object candidates = functionCache().get(namespace);
81 if (candidates instanceof Functions) {
82 return ((Functions) candidates).getFunction(
83 namespace,
84 name,
85 parameters);
86 }
87 if (candidates instanceof List) {
88 List list = (List) candidates;
89 int count = list.size();
90 for (int i = 0; i < count; i++) {
91 Function function =
92 ((Functions) list.get(i)).getFunction(
93 namespace,
94 name,
95 parameters);
96 if (function != null) {
97 return function;
98 }
99 }
100 }
101 return null;
102 }
103
104 /**
105 * Prepare the cache.
106 * @return cache map keyed by namespace
107 */
108 private synchronized Map functionCache() {
109 if (byNamespace == null) {
110 byNamespace = new HashMap();
111 int count = allFunctions.size();
112 for (int i = 0; i < count; i++) {
113 Functions funcs = (Functions) allFunctions.get(i);
114 Set namespaces = funcs.getUsedNamespaces();
115 for (Iterator it = namespaces.iterator(); it.hasNext();) {
116 String ns = (String) it.next();
117 Object candidates = byNamespace.get(ns);
118 if (candidates == null) {
119 byNamespace.put(ns, funcs);
120 }
121 else if (candidates instanceof Functions) {
122 List lst = new ArrayList();
123 lst.add(candidates);
124 lst.add(funcs);
125 byNamespace.put(ns, lst);
126 }
127 else {
128 ((List) candidates).add(funcs);
129 }
130 }
131 }
132 }
133 return byNamespace;
134 }
135 }