[xslt] "|" operator

[Phil Shafer <phil juniper net>]

This may be a dumb question, but I'm stumped.....

What's the difference between 'select=". | one"'
and 'select="(.) | one"'?  The latter does what
I thought the former should have done.

Here's is a script that does five selects and calls a
template that for-each'es thru the selected nodes and
prints their name():


<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
                version="1.0">

  <xsl:template match="top">
    <out>
      <test1>
        <xsl:variable name="test1" select=". | one"/>
        <xsl:call-template name="out">
          <xsl:with-param name="test" select="$test1"/>
        </xsl:call-template>
      </test1>

      <test2>
        <xsl:variable name="test2" select="(.) | one"/>
        <xsl:call-template name="out">
          <xsl:with-param name="test" select="$test2"/>
        </xsl:call-template>
      </test2>

      <test3>
        <xsl:variable name="top" select="."/>
        <xsl:variable name="test2" select="$top | one"/>
        <xsl:call-template name="out">
          <xsl:with-param name="test" select="$test2"/>
        </xsl:call-template>
      </test3>

      <test4>
        <xsl:variable name="test1" select=". or one"/>
        <xsl:call-template name="out">
          <xsl:with-param name="test" select="$test1"/>
        </xsl:call-template>
      </test4>

      <test5>
        <xsl:variable name="test1" select="(.) or one"/>
        <xsl:call-template name="out">
          <xsl:with-param name="test" select="$test1"/>
        </xsl:call-template>
      </test5>
    </out>
  </xsl:template>

  <xsl:template name="out">
    <xsl:param name="test"/>

    <xsl:for-each select="$test">
      <found>
        <name><xsl:value-of select="name(.)"/></name>
      </found>
    </xsl:for-each>
  </xsl:template>

</xsl:stylesheet>



Here is my test input:



<top>
  <one/>
  <two/>
  <three/>
</top>



The output of xsltproc (formatted) is:


<?xml version="1.0"?>
<out>
  <test1>
    <found>
      <name>top</name>
    </found>
  </test1>
  <test2>
    <found>
      <name>top</name>
    </found>
    <found>
      <name>one</name>
    </found>
  </test2>
  <test3>
    <found>
      <name>top</name>
    </found>
    <found>
      <name>one</name>
    </found>
  </test3>
  <test4/>
  <test5/>
</out>



The problem is that ". | one" selects only <top>, not <one>.

But if I wrap it in parens (test2) or use a variable (test3), it
works correctly.

My first guess was this was an issue with "|" as both the logic and
union operators, but test4 and test5 indicate otherwise (since
nothing was selected).

Any insight appreciated.

Thanks,
 Phil