Value


1   package org.sapia.regis.type;
2   
3   /**
4    * Wraps an object value corresponding to a <code>BuiltinType</code> (the Value/BuiltinType
5    * relation is analoguous to the Object/Primitive type relation).
6    * 
7    * @author yduchesne
8    *
9    */
10  public class Value {
11    
12    private BuiltinType type;
13    private Object   value;
14    
15    private Value(BuiltinType type, Object   value){
16      this.value = value;
17      this.type = type;
18    }
19    
20    /**
21     * @return the <code>BuiltinType</code> of this instance.
22     */
23    public BuiltinType getType(){
24      return type;
25    }
26  
27    /**
28     * Sets this instance's value, if the given object corresponds to this
29     * instance's <code>BuiltinType</code>.
30     * 
31     * @param o an <code>Object</code>
32     */
33    public void set(Object   o){
34      if(o == null){
35        this.value = o;
36      }
37      else if(type.isAssignable(o)){
38        this.value = o;
39      }
40      else{
41        throw new IllegalArgumentException  ("Invalid value: " + o + " for type: " + type.getName());
42      }
43    }
44    
45    /**
46     * Sets this instance's value, if the given string can be parsed to a
47     * value that corresponds to this instance's <code>BuiltinType</code>.
48     * 
49     * @param o a <code>String</code>.
50     * @return the <code>Object</code> value that was parsed from the given string
51     * and internally set to this instance.
52     */
53    public Object   set(String   o){
54      if(o == null){
55        this.value = o;
56      }
57      else if(type.isAssignable(o)){
58        this.value = o;
59      }
60      else{
61        this.value = this.type.parse(o);
62      }
63      return this.value;
64    }
65  
66    /**
67     * Sets the internal value of this instance to <code>null</code>.
68     */
69    public void nullify(){
70      this.value = null;
71    }
72    
73    /**
74     * @return the internal value of this instance.
75     */
76    public Object   get(){
77      return value;
78    }
79    
80    /**
81     * @param type the <code>Builtin</code> type to which the returned value 
82     * will correspond.
83     * @return a <code>Value</code>.
84     */
85    public static Value newInstance(BuiltinType type){
86      return new Value(type, null);
87    }
88    
89    /**
90     * @param type the <code>Builtin</code> type to which the returned value 
91     * will correspond.
92     * @param value a string value that corresponds to the passed in built-in type.
93     * @return a <code>Value</code>.
94     */  
95    public static Value newInstance(BuiltinType type, String   value){
96      if(value == null){
97        return new Value(type, null);
98      }
99      else{
100       return new Value(type, type.parse(value));
101     }
102   }
103   
104   /**
105    * @param type the <code>Builtin</code> type to which the returned value 
106    * will correspond.
107    * @param value an <code>Object</code> value that corresponds to the passed in built-in type.
108    * @return a <code>Value</code>.
109    */  
110   public static Value newInstance(BuiltinType type, Object   value){
111     if(value == null){
112       return new Value(type, null);
113     }
114     else if(type.isAssignable(value)){
115       return new Value(type, value);
116     }
117     else{
118       throw new IllegalArgumentException  ("Invalid value: " + value + " for type: " + type.getName());      
119     }
120   }    
121   
122 }
123
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