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.HashMap;
20
21 /**
22 * A basic implementation of the Variables interface that uses a HashMap.
23 *
24 * @author Dmitri Plotnikov
25 * @version $Revision: 652925 $ $Date: 2008-05-03 00:05:41 +0200 (Sa, 03 Mai 2008) $
26 */
27 public class BasicVariables implements Variables {
28 private static final long serialVersionUID = 2708263960832062725L;
29
30 /**
31 * Contains the values of declared variables
32 */
33 private HashMap vars = new HashMap();
34
35 /**
36 * Returns true if the variable has been defined, even if the
37 * value of the variable is null.
38 *
39 * @param varName is a variable name without the "$" sign
40 *
41 * @return true if the variable is declared
42 */
43 public boolean isDeclaredVariable(String varName) {
44 return vars.containsKey(varName);
45 }
46
47 /**
48 * Returns the value of the variable if it is defined,
49 * otherwise, throws IllegalArgumentException
50 *
51 * @param varName is a variable name without the "$" sign
52 *
53 * @return the value of the variable
54 */
55 public Object getVariable(String varName) {
56 // Note that a variable may be defined with a null value
57
58 if (vars.containsKey(varName)) {
59 return vars.get(varName);
60 }
61
62 throw new IllegalArgumentException(
63 "No such variable: '" + varName + "'");
64 }
65
66 /**
67 * Defines a new variable with the specified value or modifies
68 * the value of an existing variable.
69 *
70 * @param varName is a variable name without the "$" sign
71 * @param value is the new value for the variable, which can be null
72 */
73 public void declareVariable(String varName, Object value) {
74 vars.put(varName, value);
75 }
76
77 /**
78 * Removes an existing variable. May throw UnsupportedOperationException.
79 *
80 * @param varName is a variable name without the "$" sign
81 */
82 public void undeclareVariable(String varName) {
83 vars.remove(varName);
84 }
85
86 public String toString() {
87 return vars.toString();
88 }
89 }