001 /*
002 * Copyright 1999-2001,2004 The Apache Software Foundation.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017 package org.apache.commons.workflow.base;
018
019
020 import java.util.EmptyStackException;
021 import org.apache.commons.jxpath.JXPathContext;
022 import org.apache.commons.workflow.Context;
023 import org.apache.commons.workflow.Descriptor;
024
025
026 /**
027 * <p>Basic implementation of the <strong>Descriptor</strong> interface.</p>
028 *
029 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
030 * @author Craig R. McClanahan
031 */
032
033 public class BaseDescriptor implements Descriptor {
034
035
036 // ----------------------------------------------------------- Constructors
037
038
039 /**
040 * Create an instance with default values.
041 */
042 public BaseDescriptor() {
043
044 super();
045
046 }
047
048
049 /**
050 * Create an instance with the specified values.
051 *
052 * @param xpath The XPath reference expression
053 */
054 public BaseDescriptor(String xpath) {
055
056 this(null, null, xpath, null);
057
058 }
059
060
061 /**
062 * Create an instance with the specified values.
063 *
064 * @param xpath The XPath reference expression
065 * @param type The expected class of this object
066 */
067 public BaseDescriptor(String xpath, Class type) {
068
069 this(null, null, xpath, type);
070
071 }
072
073
074 /**
075 * Create an instance with the specified values.
076 *
077 * @param name The object name
078 * @param scope The object scope
079 */
080 public BaseDescriptor(String name, String scope) {
081
082 this(name, scope, null, null);
083
084 }
085
086
087 /**
088 * Create an instance with the specified values.
089 *
090 * @param name The object name
091 * @param scope The object scope
092 * @param type The expected class of this object
093 */
094 public BaseDescriptor(String name, String scope, Class type) {
095
096 this(name, scope, null, type);
097
098 }
099
100
101 /**
102 * Create an instance with the specified values.
103 *
104 * @param name The object name
105 * @param scope The object scope
106 * @param xpath The XPath reference expression
107 * @param type The expected class
108 */
109 public BaseDescriptor(String name, String scope,
110 String xpath, Class type) {
111
112 super();
113 setName(name);
114 setScope(scope);
115 setXpath(xpath);
116 setType(type);
117
118 }
119
120
121 // ----------------------------------------------------- Instance Variables
122
123
124 /**
125 * The name of the Java object (in some scope).
126 */
127 protected String name = null;
128
129
130 /**
131 * The scope of the Java object.
132 */
133 protected String scope = null;
134
135
136 /**
137 * The optional Java class expected by this Descriptor.
138 */
139 protected Class type = null;
140
141
142 /**
143 * The XPath expression used to access the Java object.
144 */
145 protected String xpath = null;
146
147
148 // ------------------------------------------------------------- Properties
149
150
151 /**
152 * Return the name of the Java object (in some scope) referenced by
153 * this Descriptor.
154 */
155 public String getName() {
156
157 return (this.name);
158
159 }
160
161
162 /**
163 * Set the name of the Java object (in some scope) referenced by
164 * this Descriptor.
165 *
166 * @param name The new object name
167 */
168 public void setName(String name) {
169
170 this.name = name;
171
172 }
173
174
175 /**
176 * Return the scope of the Java object referenced by this Descriptor.
177 */
178 public String getScope() {
179
180 return (this.scope);
181
182 }
183
184
185 /**
186 * Set the scope of the Java object referenced by this Descriptor.
187 *
188 * @param scope The new scope name
189 */
190 public void setScope(String scope) {
191
192 this.scope = scope;
193
194 }
195
196
197 /**
198 * Return the optional Java class expected by this Descriptor.
199 */
200 public Class getType() {
201
202 return (this.type);
203
204 }
205
206
207 /**
208 * Set the optional Java class expected by this Descriptor.
209 *
210 * @param type The new expected type
211 */
212 public void setType(Class type) {
213
214 this.type = type;
215
216 }
217
218
219 /**
220 * Return the XPath expression used to access the Java object
221 * referenced by this Descriptor.
222 */
223 public String getXpath() {
224
225 return (this.xpath);
226
227 }
228
229
230 /**
231 * Set the XPath expression used to access the Java object
232 * referenced by this Descriptor.
233 *
234 * @param xpath The new XPath expression
235 */
236 public void setXpath(String xpath) {
237
238 this.xpath = xpath;
239
240 }
241
242
243 // --------------------------------------------------------- Public Methods
244
245
246 /**
247 * Return the value specified by this Descriptor from the specified
248 * Context. If there is no such value, return <code>null</code>.
249 *
250 * @param context Context from which to retrieve this value
251 */
252 public Object get(Context context) {
253
254 if (xpath != null) {
255 JXPathContext jpc = context.getJXPathContext();
256 jpc.setLenient(true);
257 return (jpc.getValue("local/" + xpath));
258 } else if (name != null) {
259 if (scope == null)
260 return (context.get(name));
261 else {
262 int scopeId = context.getScopeId(scope);
263 return (context.get(name, scopeId));
264 }
265 } else {
266 try {
267 return (context.pop());
268 } catch (EmptyStackException e) {
269 return (null);
270 }
271 }
272
273 }
274
275
276 /**
277 * <p>Call <code>get()</code> to retrieve the value specified by this
278 * Descriptor, and then return <code>true</code> if this value represents
279 * a positive result; otherwise return <code>false</code>. A positive
280 * result depends on the data type of the retrieved value:</p>
281 * <ul>
282 * <li>Value returned is a <code>String</code> of length greater than 0.
283 * </li>
284 * <li>Value is a Boolean "true"</code>.</li>
285 * <li>Value is a numeric primitive (byte, char, float, double, int,
286 * long, short), or an Object wrapper for one of these types, and
287 * the corresponding value is non-zero.</li>
288 * <li>Value returned is a non-null Object.</li>
289 * </ul>
290 *
291 * @param context Context from which to retrieve this value
292 */
293 public boolean positive(Context context) {
294
295 Object value = get(context);
296 if (value == null)
297 return (false);
298 else if (value instanceof Boolean)
299 return (((Boolean) value).booleanValue());
300 else if (value instanceof Byte)
301 return (((Byte) value).byteValue() != (byte) 0);
302 else if (value instanceof Character)
303 return (((Character) value).charValue() != (char) 0);
304 else if (value instanceof Double)
305 return (((Double) value).doubleValue() != (double) 0.0);
306 else if (value instanceof Float)
307 return (((Double) value).floatValue() != (float) 0.0);
308 else if (value instanceof Integer)
309 return (((Integer) value).intValue() != (int) 0);
310 else if (value instanceof Long)
311 return (((Long) value).longValue() != (long) 0);
312 else if (value instanceof Short)
313 return (((Short) value).shortValue() != (short) 0);
314 else if (value instanceof String)
315 return (((String) value).length() > 0);
316 else
317 return (true); // Non-null object
318
319
320 }
321
322
323 /**
324 * Store the value into the destination specified by this Descriptor
325 * in the specified Context, replacing any existing value.
326 *
327 * @param context Context into which to store this value
328 * @param value Object value to be stored
329 */
330 public void put(Context context, Object value) {
331
332 if (xpath != null) {
333 JXPathContext jpc = context.getJXPathContext();
334 jpc.setValue("local/" + xpath, value);
335 } else {
336 if (scope == null)
337 context.put(name, value);
338 else {
339 int scopeId = context.getScopeId(scope);
340 context.put(name, value, scopeId);
341 }
342 }
343
344 }
345
346
347 /**
348 * Remove any existing value associated with this Descriptor from the
349 * specified Context.
350 *
351 * @param context Context from which to remove this value.
352 */
353 public void remove(Context context) {
354
355 if (xpath != null) {
356 throw new IllegalStateException("Cannot 'remove' throw xpath");
357 } else {
358 if (scope == null)
359 context.remove(name);
360 else {
361 int scopeId = context.getScopeId(scope);
362 context.remove(name, scopeId);
363 }
364 }
365
366 }
367
368
369 /**
370 * Render a printable version of this object.
371 */
372 public String toString() {
373
374 StringBuffer sb = new StringBuffer("<descriptor");
375 if (xpath != null) {
376 sb.append(" xpath=\"");
377 sb.append(xpath);
378 sb.append("\"");
379 }
380 if (name != null) {
381 sb.append(" name=\"");
382 sb.append(name);
383 sb.append("\"");
384 }
385 if (scope != null) {
386 sb.append(" scope=\"");
387 sb.append(scope);
388 sb.append("\"");
389 }
390 sb.append("/>");
391 return (sb.toString());
392
393 }
394
395
396 }