[Bug 1496] New - TransformerImpl.setParameter should only remember user parameters, not dynamic parameters

[bu...@apache.org]

http://nagoya.apache.org/bugzilla/show_bug.cgi?id=1496

*** shadow/1496	Wed Apr 25 06:00:38 2001
--- shadow/1496.tmp.623	Wed Apr 25 06:00:38 2001
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*** 0 ****
--- 1,77 ----
+ +============================================================================+
+ | TransformerImpl.setParameter should only remember user parameters, not dyn |
+ +----------------------------------------------------------------------------+
+ |        Bug #: 1496                        Product: XalanJ2                 |
+ |       Status: NEW                         Version: 2.0.1                   |
+ |   Resolution:                            Platform: All                     |
+ |     Severity: Normal                   OS/Version: Other                   |
+ |     Priority: Medium                    Component: org.apache.xalan.transf |
+ +----------------------------------------------------------------------------+
+ |  Assigned To: xalan-dev@xml.apache.org                                     |
+ |  Reported By: Alex.Blewitt@ioshq.com                                       |
+ |      CC list: Cc:                                                          |
+ +----------------------------------------------------------------------------+
+ |          URL:                                                              |
+ +============================================================================+
+ |                              DESCRIPTION                                   |
+ I have an XSL file that declares a variable, which is computed based on an 
+ element of the document it is processing. If I use the same Transformer to 
+ process another document, the parameter is not re-evaluated with the new value.
+ 
+ <xsl:stylesheet>
+   <xsl:param name="title" select="/Title/node()">
+ 
+   <xsl:template match="/">
+     <HTML><HEAD><TITLE><xsl:value-of select="$title"/></TITLE></HEAD><xsl:apply-
+ templates/></HTML>
+   </xsl:template>
+ </xsl:stylesheet>
+ 
+ If I create a Transformer, and then run it on:
+ 
+ doc1.xml:
+ <Title>Doc1</Title>
+ 
+ doc2.xml:
+ <Title>Doc2</Title>
+ 
+ then the outputs are:
+ 
+ out1.html:
+ <HTML><HEAD><TITLE>Doc1</TITLE></HEAD></HTML>
+ 
+ out2.html:
+ <HTML><HEAD><TITLE>Doc2</TITLE></HEAD></HTML>
+ 
+ It appears that the routine evaluating the parameter is using 'setParameter' to 
+ store the value, which is then cached (and hence, not re-evaluated) for the 
+ second document.
+ 
+ IMHO it is useful to store *user* set parameters via the transformer, but I do 
+ not believe that the same parameters should be used to store the *computed* 
+ parameters in such a way.
+ 
+ The effect can be fixed by calling 'clearParameters()' on the Transformer 
+ object between each call; however, storing user parameters is still a bonus.
+ 
+ The following will fix the problem by clearing the parameter list between calls:
+ 
+ public class NewTransformer extends TransformerImpl {
+   private Map userParams = new HashMap();
+   public void setParameter(String param, String value) {
+     userParams.put(param,value);
+   }
+   public void transform(Source source) {
+     super.clearParameters();
+     Iterator i = userParams.iterator();
+     while(i.hasNext()) { 
+       Object name = i.next();
+       Object value = userParams.get(name);
+       super.setParameter(name,value);
+     }
+     super.transform(source);
+   }
+ }
+ 
+ This can be used to give the impression to the user that his parameters are 
+ being cached, but allow the parameters to be evaluated each time.