Source code: org/objectstyle/cayenne/project/ProjectPath.java
1 /* ====================================================================
2 *
3 * The ObjectStyle Group Software License, Version 1.0
4 *
5 * Copyright (c) 2002-2003 The ObjectStyle Group
6 * and individual authors of the software. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. The end-user documentation included with the redistribution, if
21 * any, must include the following acknowlegement:
22 * "This product includes software developed by the
23 * ObjectStyle Group (http://objectstyle.org/)."
24 * Alternately, this acknowlegement may appear in the software itself,
25 * if and wherever such third-party acknowlegements normally appear.
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27 * 4. The names "ObjectStyle Group" and "Cayenne"
28 * must not be used to endorse or promote products derived
29 * from this software without prior written permission. For written
30 * permission, please contact andrus@objectstyle.org.
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32 * 5. Products derived from this software may not be called "ObjectStyle"
33 * nor may "ObjectStyle" appear in their names without prior written
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36 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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38 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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48 * ====================================================================
49 *
50 * This software consists of voluntary contributions made by many
51 * individuals on behalf of the ObjectStyle Group. For more
52 * information on the ObjectStyle Group, please see
53 * <http://objectstyle.org/>.
54 *
55 */
56 package org.objectstyle.cayenne.project;
57
58 /**
59 * Immutable holder of a selection path within a Cayenne project.
60 * Mostly used by various tools (CayenneModeler comes to mind)
61 * to navigate Cayenne projects. Contains a number of convenience methods
62 * to access path elements.
63 *
64 * <p>For instance, given a path
65 * <code>Project -> DataMap -> ObjEntity -> ObjAttribute</code>,
66 * <code>getObject</code> will return ObjAttribute, <code>getObjectParent</code> -
67 * ObjEntity, <code>getRoot</code> - Project.</p>
68 *
69 * @author Andrei Adamchik
70 */
71 public class ProjectPath {
72 public static final Object[] EMPTY_PATH = new Object[0];
73
74 protected Object[] path;
75
76 public ProjectPath() {
77 path = EMPTY_PATH;
78 }
79
80 /**
81 * Constructor for ProjectPath.
82 */
83 public ProjectPath(Object object) {
84 path = new Object[] { object };
85 }
86
87 /**
88 * Constructor for ProjectPath.
89 */
90 public ProjectPath(Object[] path) {
91 this.path = (path != null) ? path : EMPTY_PATH;
92 }
93
94 public Object[] getPath() {
95 return path;
96 }
97
98 /**
99 * Scans path, looking for the first element that
100 * is an instanceof <code>aClass</code>.
101 */
102 public Object firstInstanceOf(Class aClass) {
103 for (int i = 0; i < path.length; i++) {
104 if (path[i] != null && aClass.isAssignableFrom(path[i].getClass())) {
105 return path[i];
106 }
107 }
108
109 return null;
110 }
111
112 /**
113 * Returns an instance of the path, expanding this one by
114 * appending an object at the end.
115 */
116 public ProjectPath appendToPath(Object object) {
117 if (object != null) {
118 Object[] newPath = new Object[path.length + 1];
119
120 if (path.length > 0) {
121 System.arraycopy(path, 0, newPath, 0, path.length);
122 }
123 newPath[path.length] = object;
124 return new ProjectPath(newPath);
125 } else {
126 return this;
127 }
128 }
129
130 /**
131 * Returns the root or starting object of the path.
132 */
133 public Object getRoot() {
134 if (path.length == 0) {
135 return null;
136 }
137
138 return path[0];
139 }
140
141 /**
142 * Returns the last object in the path.
143 */
144 public Object getObject() {
145 if (path.length == 0) {
146 return null;
147 }
148
149 // return last object
150 return path[path.length - 1];
151 }
152
153 /**
154 * Returns an object corresponding to the parent node
155 * of the node represented by the path. This is the object
156 * next to last object in the path.
157 */
158 public Object getObjectParent() {
159 if (path.length == 0) {
160 return null;
161 }
162
163 // return next to last object
164 return (path.length > 1) ? path[path.length - 2] : null;
165 }
166
167 public String toString() {
168 StringBuffer buf = new StringBuffer();
169 buf.append("[ProjectPath: ");
170 for (int i = 0; i < path.length; i++) {
171 if (i > 0) {
172 buf.append(", ");
173 }
174
175 String token = (path[i] != null) ? path[i].getClass().getName() : "<null>";
176 buf.append(token);
177 }
178 buf.append("]");
179 return buf.toString();
180 }
181 }