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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.functions;
18  
19  import java.lang.reflect.InvocationTargetException;
20  import java.lang.reflect.Method;
21  import java.lang.reflect.Modifier;
22  
23  import org.apache.commons.jxpath.ExpressionContext;
24  import org.apache.commons.jxpath.Function;
25  import org.apache.commons.jxpath.JXPathInvalidAccessException;
26  import org.apache.commons.jxpath.util.TypeUtils;
27  import org.apache.commons.jxpath.util.ValueUtils;
28  
29  /**
30   * An XPath extension function implemented as an individual Java method.
31   *
32   * @author Dmitri Plotnikov
33   * @version $Revision: 652845 $ $Date: 2008-05-02 13:46:46 -0400 (Fri, 02 May 2008) $
34   */
35  public class MethodFunction implements Function {
36  
37      private Method method;
38      private static final Object[] EMPTY_ARRAY = new Object[0];
39  
40      /**
41       * Create a new MethodFunction.
42       * @param method implementing Method
43       */
44      public MethodFunction(Method method) {
45          this.method = ValueUtils.getAccessibleMethod(method);
46      }
47  
48      public Object invoke(ExpressionContext context, Object[] parameters) {
49          try {
50              Object target;
51              Object[] args;
52              if (Modifier.isStatic(method.getModifiers())) {
53                  target = null;
54                  if (parameters == null) {
55                      parameters = EMPTY_ARRAY;
56                  }
57                  int pi = 0;
58                  Class[] types = method.getParameterTypes();
59                  if (types.length >= 1
60                      && ExpressionContext.class.isAssignableFrom(types[0])) {
61                      pi = 1;
62                  }
63                  args = new Object[parameters.length + pi];
64                  if (pi == 1) {
65                      args[0] = context;
66                  }
67                  for (int i = 0; i < parameters.length; i++) {
68                      args[i + pi] =
69                          TypeUtils.convert(parameters[i], types[i + pi]);
70                  }
71              }
72              else {
73                  int pi = 0;
74                  Class[] types = method.getParameterTypes();
75                  if (types.length >= 1
76                      && ExpressionContext.class.isAssignableFrom(types[0])) {
77                      pi = 1;
78                  }
79                  target =
80                      TypeUtils.convert(
81                          parameters[0],
82                          method.getDeclaringClass());
83                  args = new Object[parameters.length - 1 + pi];
84                  if (pi == 1) {
85                      args[0] = context;
86                  }
87                  for (int i = 1; i < parameters.length; i++) {
88                      args[pi + i - 1] =
89                          TypeUtils.convert(parameters[i], types[i + pi - 1]);
90                  }
91              }
92  
93              return method.invoke(target, args);
94          }
95          catch (Throwable ex) {
96              if (ex instanceof InvocationTargetException) {
97                  ex = ((InvocationTargetException) ex).getTargetException();
98              }
99              throw new JXPathInvalidAccessException("Cannot invoke " + method,
100                     ex);
101         }
102     }
103 
104     public String toString() {
105         return method.toString();
106     }
107 }