ElemValueOf


1   /*
2    * Copyright 1999-2004 The Apache Software Foundation.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  /*
17   * $Id: ElemValueOf.java,v 1.24 2004/02/16 20:32:33 minchau Exp $
18   */
19  package org.apache.xalan.templates;
20  
21  import javax.xml.transform.TransformerException  ;
22  
23  import org.apache.xalan.res.XSLTErrorResources;
24  import org.apache.xalan.transformer.TransformerImpl;
25  import org.apache.xml.dtm.DTM;
26  import org.apache.xml.serializer.SerializationHandler;
27  import org.apache.xpath.Expression;
28  import org.apache.xpath.XPath;
29  import org.apache.xpath.XPathContext;
30  import org.apache.xpath.objects.XObject;
31  import org.xml.sax.SAXException  ;
32  
33  /**
34   * Implement xsl:value-of.
35   * <pre>
36   * <!ELEMENT xsl:value-of EMPTY>
37   * <!ATTLIST xsl:value-of
38   *   select %expr; #REQUIRED
39   *   disable-output-escaping (yes|no) "no"
40   * >
41   * </pre>
42   * @see <a HREF="http://www.w3.org/TR/xslt#value-of">value-of in XSLT Specification</a>
43   * @xsl.usage advanced
44   */
45  public class ElemValueOf extends ElemTemplateElement
46  {
47  
48    /**
49     * The select expression to be executed.
50     * @serial
51     */
52    private XPath m_selectExpression = null;
53  
54    /**
55     * True if the pattern is a simple ".".
56     * @serial
57     */
58    private boolean m_isDot = false;
59  
60    /**
61     * Set the "select" attribute.
62     * The required select attribute is an expression; this expression
63     * is evaluated and the resulting object is converted to a
64     * string as if by a call to the string function.
65     *
66     * @param v The value to set for the "select" attribute.
67     */
68    public void setSelect(XPath v)
69    {
70  
71      if (null != v)
72      {
73        String   s = v.getPatternString();
74  
75        m_isDot = (null != s) && s.equals(".");
76      }
77  
78      m_selectExpression = v;
79    }
80  
81    /**
82     * Get the "select" attribute.
83     * The required select attribute is an expression; this expression
84     * is evaluated and the resulting object is converted to a
85     * string as if by a call to the string function.
86     *
87     * @return The value of the "select" attribute.
88     */
89    public XPath getSelect()
90    {
91      return m_selectExpression;
92    }
93  
94    /**
95     * Tells if this element should disable escaping.
96     * @serial
97     */
98    private boolean m_disableOutputEscaping = false;
99  
100   /**
101    * Set the "disable-output-escaping" attribute.
102    * Normally, the xml output method escapes & and < (and
103    * possibly other characters) when outputting text nodes.
104    * This ensures that the output is well-formed XML. However,
105    * it is sometimes convenient to be able to produce output
106    * that is almost, but not quite well-formed XML; for
107    * example, the output may include ill-formed sections
108    * which are intended to be transformed into well-formed
109    * XML by a subsequent non-XML aware process. For this reason,
110    * XSLT provides a mechanism for disabling output escaping.
111    * An xsl:value-of or xsl:text element may have a
112    * disable-output-escaping attribute; the allowed values
113    * are yes or no; the default is no; if the value is yes,
114    * then a text node generated by instantiating the xsl:value-of
115    * or xsl:text element should be output without any escaping.
116    * @see <a HREF="http://www.w3.org/TR/xslt#disable-output-escaping">disable-output-escaping in XSLT Specification</a>
117    *
118    * @param v The value to set for the "disable-output-escaping" attribute.
119    */
120   public void setDisableOutputEscaping(boolean v)
121   {
122     m_disableOutputEscaping = v;
123   }
124 
125   /**
126    * Get the "disable-output-escaping" attribute.
127    * Normally, the xml output method escapes & and < (and
128    * possibly other characters) when outputting text nodes.
129    * This ensures that the output is well-formed XML. However,
130    * it is sometimes convenient to be able to produce output
131    * that is almost, but not quite well-formed XML; for
132    * example, the output may include ill-formed sections
133    * which are intended to be transformed into well-formed
134    * XML by a subsequent non-XML aware process. For this reason,
135    * XSLT provides a mechanism for disabling output escaping.
136    * An xsl:value-of or xsl:text element may have a
137    * disable-output-escaping attribute; the allowed values
138    * are yes or no; the default is no; if the value is yes,
139    * then a text node generated by instantiating the xsl:value-of
140    * or xsl:text element should be output without any escaping.
141    * @see <a HREF="http://www.w3.org/TR/xslt#disable-output-escaping">disable-output-escaping in XSLT Specification</a>
142    *
143    * @return The value of the "disable-output-escaping" attribute.
144    */
145   public boolean getDisableOutputEscaping()
146   {
147     return m_disableOutputEscaping;
148   }
149 
150   /**
151    * Get an integer representation of the element type.
152    *
153    * @return An integer representation of the element, defined in the
154    *     Constants class.
155    * @see org.apache.xalan.templates.Constants
156    */
157   public int getXSLToken()
158   {
159     return Constants.ELEMNAME_VALUEOF;
160   }
161 
162   /**
163    * This function is called after everything else has been
164    * recomposed, and allows the template to set remaining
165    * values that may be based on some other property that
166    * depends on recomposition.
167    *
168    * NEEDSDOC @param sroot
169    *
170    * @throws TransformerException
171    */
172   public void compose(StylesheetRoot sroot) throws TransformerException  
173   {
174 
175     super.compose(sroot);
176 
177     java.util.Vector   vnames = sroot.getComposeState().getVariableNames();
178 
179     if (null != m_selectExpression)
180       m_selectExpression.fixupVariables(
181         vnames, sroot.getComposeState().getGlobalsSize());
182   }
183 
184   /**
185    * Return the node name.
186    *
187    * @return The node name
188    */
189   public String   getNodeName()
190   {
191     return Constants.ELEMNAME_VALUEOF_STRING;
192   }
193 
194   /**
195    * Execute the string expression and copy the text to the
196    * result tree.
197    * The required select attribute is an expression; this expression
198    * is evaluated and the resulting object is converted to a string
199    * as if by a call to the string function. The string specifies
200    * the string-value of the created text node. If the string is
201    * empty, no text node will be created. The created text node will
202    * be merged with any adjacent text nodes.
203    * @see <a HREF="http://www.w3.org/TR/xslt#value-of">value-of in XSLT Specification</a>
204    *
205    * @param transformer non-null reference to the the current transform-time state.
206    * @param sourceNode non-null reference to the <a HREF="http://www.w3.org/TR/xslt#dt-current-node">current source node</a>.
207    * @param mode reference, which may be null, to the <a HREF="http://www.w3.org/TR/xslt#modes">current mode</a>.
208    *
209    * @throws TransformerException
210    */
211   public void execute(TransformerImpl transformer) throws TransformerException  
212   {
213 
214     XPathContext xctxt = transformer.getXPathContext();
215     SerializationHandler rth = transformer.getResultTreeHandler();
216 
217     if (TransformerImpl.S_DEBUG)
218       transformer.getTraceManager().fireTraceEvent(this);
219 
220     try
221     {
222       // Optimize for "."
223       if (false && m_isDot && !TransformerImpl.S_DEBUG)
224       {
225         int child = xctxt.getCurrentNode();
226         DTM dtm = xctxt.getDTM(child);
227 
228         xctxt.pushCurrentNode(child);
229 
230         if (m_disableOutputEscaping)
231           rth.processingInstruction(
232             javax.xml.transform.Result.PI_DISABLE_OUTPUT_ESCAPING, "");
233 
234         try
235         {
236           dtm.dispatchCharactersEvents(child, rth, false);
237         }
238         finally
239         {
240           if (m_disableOutputEscaping)
241             rth.processingInstruction(
242               javax.xml.transform.Result.PI_ENABLE_OUTPUT_ESCAPING, "");
243 
244           xctxt.popCurrentNode();
245         }
246       }
247       else
248       {
249         xctxt.pushNamespaceContext(this);
250 
251         int current = xctxt.getCurrentNode();
252 
253         xctxt.pushCurrentNodeAndExpression(current, current);
254 
255         if (m_disableOutputEscaping)
256           rth.processingInstruction(
257             javax.xml.transform.Result.PI_DISABLE_OUTPUT_ESCAPING, "");
258 
259         try
260         {
261           Expression expr = m_selectExpression.getExpression();
262 
263           if (TransformerImpl.S_DEBUG)
264           {
265             XObject obj = expr.execute(xctxt);
266 
267             transformer.getTraceManager().fireSelectedEvent(current, this,
268                     "select", m_selectExpression, obj);
269             obj.dispatchCharactersEvents(rth);
270           }
271           else
272           {
273             expr.executeCharsToContentHandler(xctxt, rth);
274           }
275         }
276         finally
277         {
278           if (m_disableOutputEscaping)
279             rth.processingInstruction(
280               javax.xml.transform.Result.PI_ENABLE_OUTPUT_ESCAPING, "");
281 
282           xctxt.popNamespaceContext();
283           xctxt.popCurrentNodeAndExpression();
284         }
285       }
286     }
287     catch (SAXException   se)
288     {
289       throw new TransformerException  (se);
290     }
291     catch (RuntimeException   re) {
292         TransformerException   te = new TransformerException  (re);
293         te.setLocator(this);
294         throw te;
295     }
296     finally
297     {
298       if (TransformerImpl.S_DEBUG)
299         transformer.getTraceManager().fireTraceEndEvent(this); 
300     }
301   }
302 
303   /**
304    * Add a child to the child list.
305    *
306    * @param newChild Child to add to children list
307    *
308    * @return Child just added to children list
309    *
310    * @throws DOMException
311    */
312   public ElemTemplateElement appendChild(ElemTemplateElement newChild)
313   {
314 
315     error(XSLTErrorResources.ER_CANNOT_ADD,
316           new Object  []{ newChild.getNodeName(),
317                         this.getNodeName() });  //"Can not add " +((ElemTemplateElement)newChild).m_elemName +
318 
319     //" to " + this.m_elemName);
320     return null;
321   }
322   
323   /**
324    * Call the children visitors.
325    * @param visitor The visitor whose appropriate method will be called.
326    */
327   protected void callChildVisitors(XSLTVisitor visitor, boolean callAttrs)
328   {
329     if(callAttrs)
330         m_selectExpression.getExpression().callVisitors(m_selectExpression, visitor);
331     super.callChildVisitors(visitor, callAttrs);
332   }
333 
334 }
335
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