BUG: Position() and Last() XPath Functions Are Ignored When You Use Them as XSLT Function Arguments (324033)

MORE INFORMATION

Steps to Reproduce the Behavior

1. In Microsoft Visual Studio .NET, create a new Visual Basic .NET Console Application project.
2. Use the following code to create and add an XML document named Repro.xml to the project:

   <Data>
   	<value>1</value>
   	<value>2</value>
   	<value>3</value>
   	<value>78</value>
   	<value>5</value>
   	<value>88</value>
   	<value>7</value>
   </Data>
   					

3. Use the following code to create and add an XSLT style sheet named Repro.xsl to the project. Study the inline comments to understand the functionality of the code in the style sheet:

   <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   
       <xsl:key name="Values" match="value" use="."/>
   
       <xsl:template match="Data">
   	<Data>
   	        
   	<!-- 
   
   	Use the XSLT key() function to identify and output 
   	value elements whose value matches their position in the source XML. 
   
   	The following will not work because the position() function is supplied 
   	directly as an argument of the key() function. 
   
   	--> 
   	<ValuesThatMatchPosition>        
   		<xsl:for-each select="value">
          		    <xsl:if test="key('Values',position())">
   		            <value><xsl:value-of select="."/></value>   		    
   		   </xsl:if>	   
   		</xsl:for-each>	
       	</ValuesThatMatchPosition>
   
   	<!-- 
   
   	The position() function works correctly when used in a predicate in an expression supplied
   	as an XSLT function (the format-number function is used in this sample) argument. 
   
   	The select expression in the following line will retrieve the value of the 3rd value element 
   	in the source XML.
   
   	--> 
   	
   	<Position3Value><xsl:value-of select="format-number(value[position()=3],'0')"/></Position3Value>	
           
   	</Data>
       </xsl:template>       
   
   </xsl:stylesheet> 
   					

4. Paste the following code in the Sub Main() procedure in Module1.vb to execute the XSLT transformation by applying Repro.xsl to Repro.xml:

    Dim transform As New System.Xml.Xsl.XslTransform()
    transform.Load("..\Repro.xsl")
    transform.Transform("..\Repro.xml", "..\output.xml")
    Console.WriteLine("Done")
    Dim response As String = Console.ReadLine
   					

5. Save and run the project. The code in the Sub Main() procedure executes the XSLT transformation and writes the transformation output to a file named Output.xml in the project folder. The message "Done" appears in the console window when the transformation completes. Press any key to close the console window and return to the development environment.
6. In Solution Explorer, click Refresh button to view the Output.xml file in the project folder. When you open the Output.xml file, you will see that it contains the following XML:

   <?xml version="1.0" encoding="utf-8"?>
   <Data>
   	<ValuesThatMatchPosition></ValuesThatMatchPosition>
   	<Position3Value>3</Position3Value>
   </Data>
   					

   The value elements in the source XML whose values match their position are not listed in the output as expected. The <Position3Element> element, however, has the correct value because the expression that is used in the style sheet to retrieve it uses the position function in a predicate (instead of directly as an XSLT function argument).
   
   
7. Close Output.xml, and then open the Repro.xsl style sheet.
8. Replace the <xsl:for-each> block that is used to generate the contents of the <ValuesThatMatchPosition> element with the following code to store the output of the position XPath function in an XSLT variable and supply the variable as the value parameter in the call to the key XSLT function:

   <xsl:for-each select="value">
      <xsl:variable name="pos" select="position()"/>			
      <xsl:if test="key('Values',$pos)">
               <value><xsl:value-of select="."/></value>   		    
      </xsl:if>	   
   </xsl:for-each>
   					

9. Save the changes to the style sheet, and then reexecute the project. When you view the contents of Output.xml, you see the following XML:

   <?xml version="1.0" encoding="utf-8"?>
   <Data>
   	<ValuesThatMatchPosition>
   		<value>1</value>
   		<value>2</value>
   		<value>3</value>
   		<value>5</value>
   		<value>7</value>
   	</ValuesThatMatchPosition>
   	<Position3Value>3</Position3Value>
   </Data>
   					

   The output now lists the value elements in the source XML whose values match their position.