Source code: org/progeeks/meta/DeferredPropertyType.java
1 /*
2 * $Id: DeferredPropertyType.java,v 1.3 2003/09/01 04:38:07 pspeed Exp $
3 *
4 * Copyright (c) 2001-2002, Paul Speed
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1) Redistributions of source code must retain the above copyright notice,
12 * this list of conditions and the following disclaimer.
13 * 2) Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3) Neither the names "Progeeks", "Meta-JB", nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 package org.progeeks.meta;
34
35 /**
36 * Represents an unresolved property type of a meta-object. This
37 * is to support deferred resolution of property types within a
38 * meta-class. The actual functionality of the PropertyType implementation
39 * throws UnsupportedOperationExceptions since these operations cannot
40 * be done without resolving the type. When the type has been resolved
41 * within the meta-class it will be replaced with the real type.
42 *
43 * @version $Revision: 1.3 $
44 * @author Paul Speed
45 */
46 public class DeferredPropertyType implements PropertyType
47 {
48 private String metaClassName;
49 private PropertyType alternateType;
50
51 /**
52 * Creates a deferred type the will resolve to the specified meta-class
53 * when resolution is requested. If the meta-class does not exist then
54 * an exception will be thrown.
55 */
56 public DeferredPropertyType( String metaClassName )
57 {
58 this( metaClassName, null );
59 }
60
61 /**
62 * Creates a deferred type the will resolve to the specified meta-class
63 * when resolution is requested. If the meta-class does not exist then
64 * the alternate type is returned.
65 */
66 public DeferredPropertyType( String metaClassName, PropertyType alternateType )
67 {
68 if( metaClassName == null )
69 throw new IllegalArgumentException( "MetaClass name cannot be null." );
70 this.metaClassName = metaClassName;
71 this.alternateType = alternateType;
72 }
73
74 /**
75 * Returns the replacement property type as can be
76 * resolved from the specified class registry.
77 */
78 public PropertyType resolveType( MetaClassRegistry registry )
79 {
80 MetaClass mc = registry.getMetaClass( metaClassName );
81 if( mc != null )
82 return( new MetaClassPropertyType( mc ) );
83 if( alternateType != null )
84 return( alternateType );
85 throw new RuntimeException( "MetaClass not found for name:" + metaClassName );
86 }
87
88 /**
89 * Returns the Java class upon which this property type
90 * is based.
91 */
92 public Class getBaseClass()
93 {
94 throw new UnsupportedOperationException( "Cannot get the base class for a deferred type:"
95 + metaClassName );
96 }
97
98 /**
99 * Returns true if the specified object is an instance
100 * of this type.
101 */
102 public boolean isInstance( Object obj )
103 {
104 throw new UnsupportedOperationException( "Cannot perform instance check for a deferred type:"
105 + metaClassName );
106 }
107
108 public String toString()
109 {
110 return( "DeferredPropertyType[" + metaClassName + ", " + alternateType + "]" );
111 }
112 }