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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  
18  package org.apache.commons.jxpath;
19  
20  import java.util.HashMap;
21  
22  /**
23   * A basic implementation of the Variables interface that uses a HashMap.
24   */
25  public class BasicVariables implements Variables {
26  
27      private static final long serialVersionUID = 2708263960832062725L;
28  
29      /**
30       * Contains the values of declared variables
31       */
32      private final HashMap vars = new HashMap();
33  
34      /**
35       * Constructs a new instance.
36       */
37      public BasicVariables() {
38          // empty
39      }
40  
41      /**
42       * Defines a new variable with the specified value or modifies the value of an existing variable.
43       *
44       * @param varName is a variable name without the "$" sign
45       * @param value   is the new value for the variable, which can be null
46       */
47      @Override
48      public void declareVariable(final String varName, final Object value) {
49          vars.put(varName, value);
50      }
51  
52      /**
53       * Returns the value of the variable if it is defined, otherwise, throws IllegalArgumentException
54       *
55       * @param varName is a variable name without the "$" sign
56       * @return the value of the variable
57       */
58      @Override
59      public Object getVariable(final String varName) {
60          // Note that a variable may be defined with a null value
61          if (vars.containsKey(varName)) {
62              return vars.get(varName);
63          }
64          throw new IllegalArgumentException("No such variable: '" + varName + "'");
65      }
66  
67      /**
68       * Returns true if the variable has been defined, even if the value of the variable is null.
69       *
70       * @param varName is a variable name without the "$" sign
71       * @return true if the variable is declared
72       */
73      @Override
74      public boolean isDeclaredVariable(final String varName) {
75          return vars.containsKey(varName);
76      }
77  
78      @Override
79      public String toString() {
80          return vars.toString();
81      }
82  
83      /**
84       * Removes an existing variable. May throw UnsupportedOperationException.
85       *
86       * @param varName is a variable name without the "$" sign
87       */
88      @Override
89      public void undeclareVariable(final String varName) {
90          vars.remove(varName);
91      }
92  }