EjenChildNode


1   //
2   // Ejen (code generation system)
3   // Copyright (C) 2001, 2002 Fran�ois Wolff (ejen@noos.fr).
4   //
5   // This file is part of Ejen.
6   //
7   // Ejen is free software; you can redistribute it and/or modify
8   // it under the terms of the GNU General Public License as published by
9   // the Free Software Foundation; either version 2 of the License, or
10  // (at your option) any later version.
11  //
12  // Ejen is distributed in the hope that it will be useful,
13  // but WITHOUT ANY WARRANTY; without even the implied warranty of
14  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  // GNU General Public License for more details.
16  //
17  // You should have received a copy of the GNU General Public License
18  // along with Ejen; if not, write to the Free Software
19  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  //
21  package org.ejen;
22  
23  import org.ejen.util.XSLUtil;
24  import java.util.Properties  ;
25  import java.util.Vector  ;
26  import javax.xml.transform.dom.DOMSource  ;
27  import org.apache.xalan.transformer.TransformerImpl;
28  import org.apache.xalan.processor.StylesheetHandler;
29  
30  /**
31   * Parent abstract class of all Ejen...Node classes.
32   * @author F. Wolff
33   * @version 1.0
34   */
35  public abstract class EjenChildNode implements EjenConstants {
36  
37      /** Stack of contexts (current transformer,...) */
38      private static final EjenContextsStack _ejenContextsStack = new EjenContextsStack();
39  
40      /** Current listener for message/error reporting. */
41      private static EjenListener _ejenListener = null;
42  
43      /** Indentation string for message reporting. */
44      protected static String   _messageIndent = "";
45  
46      /**
47       * Current state of this EjenChildNode
48       * ({@link org.ejen.EjenConstants#STATE_IDLE}).
49       */
50      private int _state = STATE_IDLE;
51  
52      /**
53       * Returns the name of this EjenChildNode.
54       * @return name of this EjenChildNode.
55       */
56      public abstract String   nodeName();
57  
58      /**
59       * Returns the attributes of this EjenChildNode (empty here).
60       * @return a Properties that contains all attributes of this EjenChildNode.
61       */
62      public Properties   getAttributes() {
63          return new Properties  ();
64      }
65  
66      /**
67       * Returns the children of this EjenChildNode (empty here).
68       * @return a Vector that contains all children of this EjenChildNode.
69       */
70      public Vector   getChildren() {
71          return new Vector  ();
72      }
73  
74      /**
75       * Check this EjenChildNode for mandatory attributes/child nodes.
76       * Only sends a state change event here ({@link org.ejen.EjenConstants#STATE_CHECK}).
77       */
78      public void check() {
79          _state = STATE_CHECK;
80          sendStateEvent();
81      }
82      
83      /**
84       * Prepares this EjenChildNode execution.
85       * Only sends a state change event here ({@link org.ejen.EjenConstants#STATE_BEFORE_PROCESS}).
86       */
87      public void beforeProcess() {
88          _state = STATE_BEFORE_PROCESS;
89          sendStateEvent();
90      }
91  
92      /**
93       * Executes this EjenChildNode.
94       * Only sends a state change event here ({@link org.ejen.EjenConstants#STATE_PROCESS}).
95       */
96      public void process() {
97          _state = STATE_PROCESS;
98          sendStateEvent();
99      }
100 
101     /**
102      * Does post-execution actions after this EjenChildNode execution.
103      * Only sends a state change event here ({@link org.ejen.EjenConstants#STATE_AFTER_PROCESS}).
104      */
105     public void afterProcess() {
106         _state = STATE_AFTER_PROCESS;
107         sendStateEvent();
108     }
109 
110     /**
111      * Signals that this EjenChildNode has completly terminated its execution (including
112      * any post-execution actions).
113      * Only sends a state change event here ({@link org.ejen.EjenConstants#STATE_IDLE}).
114      */
115     public final void idle() {
116         _state = STATE_IDLE;
117         sendStateEvent();
118     }
119     
120     /**
121      * Returns the current state of this EjenChildNode.
122      * @return the current state (see {@link org.ejen.EjenConstants}).
123      */
124     public final int getState() {
125         return _state;
126     }
127 
128     /**
129      * Sets the listener for all EjenChildNode classes (the listener is static).
130      * @param ejenListener the new EjenListener.
131      */
132     public static final void setListener(EjenListener ejenListener) {
133         _ejenListener = ejenListener;
134     }
135 
136     /**
137      * Returns the current listener for all EjenChildNode classes (the listener is static).
138      * @return the current EjenListener.
139      */
140     public static final EjenListener getListener() {
141         return _ejenListener;
142     }
143 
144     /**
145      * Sends a state change event (according to the current state of this EjenChildNode).
146      * Does nothing if there is no listener.
147      */
148     public final void sendStateEvent() {
149         if (_ejenListener != null) {
150             _ejenListener.stateChanged(new EjenEvent(this, STATES[_state],
151                     MSG_VERBOSE));
152         }
153     }
154 
155     /**
156      * Sends a message event from this EjenChildNode (with level
157      * Does nothing if there is no listener.
158      * {@link org.ejen.EjenConstants#MSG_INFO}).
159      * @param msg the message to send to the listener.
160      */
161     public final void sendMessageEvent(String   msg) {
162         sendMessageEvent(msg, MSG_INFO);
163     }
164 
165     /**
166      * Sends a message event from this EjenChildNode (with a specific level).
167      * Does nothing if there is no listener.
168      * @param msg the message to send to the listener.
169      * @param level level of the message (see {@link org.ejen.EjenConstants}).
170      */
171     public final void sendMessageEvent(String   msg, int level) {
172         if (_ejenListener != null) {
173             _ejenListener.nodeMessageSent(new EjenEvent(this,
174                     _messageIndent + msg, level));
175         }
176     }
177 
178     /**
179      * Sends a message event from an XSL file (via the
180      * {@link org.ejen.ext.Messenger#send(XSLProcessorContext context, ElemExtensionCall elem)}
181      * extension function).
182      * Does nothing if there is no listener.
183      * @param msg the message to send to the listener.
184      */
185     public static final void sendXSLMessageEvent(String   msg) {
186         sendXSLMessageEvent(msg, MSG_INFO);
187     }
188 
189     /**
190      * Sends a message event from an XSL file (via the
191      * {@link org.ejen.ext.Messenger#send(XSLProcessorContext context, ElemExtensionCall elem)}
192      * extension function), with specific level.
193      * Does nothing if there is no listener.
194      * @param msg the message to send to the listener.
195      * @param level level of the message (see {@link org.ejen.EjenConstants}).
196      */
197     public static final void sendXSLMessageEvent(String   msg, int level) {
198         if (_ejenListener != null) {
199             _ejenListener.xslMessageSent(new EjenEvent("(xsl)",
200                     _messageIndent + "[xsl] " + msg, level));
201         }
202     }
203 
204     /**
205      * Returns the String representation of this EjenChildNode, in the form of
206      * "&lt;node_name&gt;&nbsp;{[&lt;attribute_name_1&gt;=&lt;attribute_value_1&gt;[,&nbsp;&lt;attribute_name_2&gt;=&lt;attribute_value_2&gt;&nbsp;...]]}".
207      * @return the String representation of this EjenChildNode.
208      */
209     public final String   toString() {
210         return nodeName() + " " + getAttributes();
211     }
212     
213     /**
214      * Returns an Object (whose name is 'name') from the current context stack.
215      * @param name name of the Object to be returned.
216      * @return the Object (may be null if there is no such name).
217      */
218     protected final Object   getFromContext(String   name) {
219         return _ejenContextsStack.peekContext().get(name);
220     }
221     
222     /**
223      * Returns an Object (whose name is 'name') from the current context stack.
224      * @param name name of the value to be returned.
225      * @param offset a negative value or zero (to access any context in the stack).
226      * @return the Object (may be null if there is no such name).
227      * @throws java.util.EmptyStackException if the stack is empty.
228      */
229     protected final Object   getFromContext(String   name, int offset) {
230         return _ejenContextsStack.peekContext(_ejenContextsStack.size() + offset - 1).get(name);
231     }
232     
233     /**
234      * Returns an Object (whose name is 'name') from the global (shared) context.
235      * @param name name of the value to be returned.
236      * @return the Object (may be null if there is no such name).
237      */
238     protected final Object   getFromGlobalContext(String   name) {
239         return _ejenContextsStack.globalGet(name);
240     }
241     
242     /**
243      * Puts an Object (whose name is 'name') in the current context (on the top
244      * of the stack).
245      * @param name name of the Object to be put in the context.
246      * @param value the Object.
247      * @return the previous Object mapped to the name (may be null).
248      */
249     protected final Object   putInContext(String   name, Object   value) {
250         return _ejenContextsStack.peekContext().put(name, value);
251     }
252     
253     /**
254      * Puts an Object (whose name is 'name') in the global (shared) context.
255      * @param name name of the Object to be put in the context.
256      * @param value the Object.
257      * @return the previous Object mapped to the name (may be null).
258      */
259     protected final Object   putInGlobalContext(String   name, Object   value) {
260         return _ejenContextsStack.globalPut(name, value);
261     }
262     
263     /**
264      * Pops the current context from the contexts stack.
265      * @return the current EjenContext (may not be null).
266      * @throws java.util.EmptyStackException if the stack is empty.
267      */
268     protected final EjenContext popContext() {
269         return _ejenContextsStack.popContext();
270     }
271     
272     /**
273      * Pushes a new EjenContext onto the top of the contexts stack.
274      * @param ejenContext the new EjenContext to be pushed.
275      * @throws java.util.EmptyStackException if the stack is empty.
276      */
277     protected final EjenContext pushContext(EjenContext ejenContext) {
278         return _ejenContextsStack.pushContext(ejenContext);
279     }
280     
281     /**
282      * Duplicates the current context (or creates a new one if the stack is empty).
283      * @return the cloned context.
284      */
285     protected final EjenContext cloneContext() {
286         if (!_ejenContextsStack.isEmpty()) {
287             return new EjenContext(_ejenContextsStack.peekContext());
288         } else {
289             return new EjenContext();
290         }
291     }
292     
293     /**
294      * Returns the evaluation of an Attribute Value Template.
295      * @param avt the Attribute Value Template.
296      * @return the evaluation of the Attribute Value Template.
297      * @throws org.ejen.EjenException if something goes wrong.
298      */
299     protected final String   evaluateAVT(String   avt) {
300         TransformerImpl ti = null;
301 
302         try {
303             ti = (TransformerImpl) (getFromGlobalContext(CTX_TRANSFORMER_IMPL));
304         } catch (Exception   e) {
305             throw new EjenException(this, null, e);
306         }           
307         if (ti == null) {
308             throw new EjenException(this,
309                     "no '" + CTX_TRANSFORMER_IMPL + "' in global context");
310         }
311         
312         return evaluateAVT(ti, avt);
313     }
314     
315     /**
316      * Returns the evaluation of an Attribute Value Template, using the provided
317      * TransformerImpl object.
318      * @param ti a TransformerImpl instance.
319      * @param avt the Attribute Value Template.
320      * @return the evaluation of the Attribute Value Template.
321      * @throws org.ejen.EjenException if something goes wrong.
322      */
323     protected final String   evaluateAVT(TransformerImpl ti, String   avt) {
324         StylesheetHandler sh = null;
325         DOMSource   src = null;
326 
327         try {
328             src = (DOMSource  ) (getFromGlobalContext(CTX_DOM_SOURCE));
329             sh = (StylesheetHandler) (getFromGlobalContext(CTX_STYLESHEET_HANDLER));
330         } catch (Exception   e) {
331             throw new EjenException(this, null, e);
332         }           
333         if (sh == null) {
334             throw new EjenException(this,
335                     "no '" + CTX_STYLESHEET_HANDLER + "' in global context");
336         }
337         if (src == null) {
338             throw new EjenException(this,
339                     "no '" + CTX_DOM_SOURCE + "' in global context");
340         }
341         try {
342             String   s = XSLUtil.evaluateAttribute(sh, ti.getXPathContext(),
343                     src.getNode(), avt);
344 
345             if (!s.equals(avt)) {
346                 sendMessageEvent("Resolved '" + avt + "' into '" + s + "'");
347             }
348             return s;
349         } catch (Exception   e) {
350             throw new EjenException(this, null, e);
351         }
352     }
353 }
354
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