FacadeTaskHelper


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  
19  package org.apache.tools.ant.util.facade;
20  
21  import java.util.Enumeration  ;
22  import java.util.Vector  ;
23  
24  /**
25   * Helper class for facade implementations - encapsulates treatment of
26   * explicit implementation choices, magic properties and
27   * implementation specific command line arguments.
28   *
29   *
30   * @since Ant 1.5
31   */
32  public class FacadeTaskHelper {
33  
34      /**
35       * Command line arguments.
36       */
37      private Vector   args = new Vector  ();
38  
39      /**
40       * The explicitly chosen implementation.
41       */
42      private String   userChoice;
43  
44      /**
45       * The magic property to consult.
46       */
47      private String   magicValue;
48  
49      /**
50       * The default value.
51       */
52      private String   defaultValue;
53  
54      /**
55       * @param defaultValue The default value for the implementation.
56       * Must not be null.
57       */
58      public FacadeTaskHelper(String   defaultValue) {
59          this(defaultValue, null);
60      }
61  
62      /**
63       * @param defaultValue The default value for the implementation.
64       * Must not be null.
65       * @param magicValue the value of a magic property that may hold a user.
66       * choice.  May be null.
67       */
68      public FacadeTaskHelper(String   defaultValue, String   magicValue) {
69          this.defaultValue = defaultValue;
70          this.magicValue = magicValue;
71      }
72  
73      /**
74       * Used to set the value of the magic property.
75       * @param magicValue the value of a magic property that may hold a user.
76       */
77      public void setMagicValue(String   magicValue) {
78          this.magicValue = magicValue;
79      }
80  
81      /**
82       * Used for explicit user choices.
83       * @param userChoice the explicitly chosen implementation.
84       */
85      public void setImplementation(String   userChoice) {
86          this.userChoice = userChoice;
87      }
88  
89      /**
90       * Retrieves the implementation.
91       * @return the implementation.
92       */
93      public String   getImplementation() {
94          return userChoice != null ? userChoice
95                                    : (magicValue != null ? magicValue
96                                                          : defaultValue);
97      }
98  
99      /**
100      * Retrieves the explicit user choice.
101      * @return the explicit user choice.
102      */
103     public String   getExplicitChoice() {
104         return userChoice;
105     }
106 
107     /**
108      * Command line argument.
109      * @param arg an argument to add.
110      */
111     public void addImplementationArgument(ImplementationSpecificArgument arg) {
112         args.addElement(arg);
113     }
114 
115     /**
116      * Retrieves the command line arguments enabled for the current
117      * facade implementation.
118      * @return an array of command line arguements.
119      */
120     public String  [] getArgs() {
121         Vector   tmp = new Vector  (args.size());
122         for (Enumeration   e = args.elements(); e.hasMoreElements();) {
123             ImplementationSpecificArgument arg =
124                 ((ImplementationSpecificArgument) e.nextElement());
125             String  [] curr = arg.getParts(getImplementation());
126             for (int i = 0; i < curr.length; i++) {
127                 tmp.addElement(curr[i]);
128             }
129         }
130         String  [] res = new String  [tmp.size()];
131         tmp.copyInto(res);
132         return res;
133     }
134 
135     /**
136      * Tests whether the implementation has been chosen by the user
137      * (either via a magic property or explicitly.
138      * @return true if magic or user choice has be set.
139      * @since Ant 1.5.2
140      */
141     public boolean hasBeenSet() {
142         return userChoice != null || magicValue != null;
143     }
144 }
145
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