Virtual Filesystems Are Virtual Office Documents

Listing 4. Exploring Our New XSLT Filesystem

$ bash
$ URL='xsltfs://context/file/tmp/example/
↪example.xml?stylesheet=example.xsl'
$ cd /tmp/example
$ ls
example-rev.xsl  example.xml  example.xsl
$ export LIBFERRIS_XSLTFS_SHEETS_URL=`pwd`
$ ferrisls -l $URL
   0 root
$ ferrisls -l $URL/root
  23 file3
   3 file7

$ fcat $URL
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<root>

 <context name="file3"
 original-url="file:///tmp/example/example.xml/root/file3"
  >filesystems inside XML?</context>

  <context name="file7"
    original-url="file:///tmp/example/example.xml/root/file7"
  >foo</context>

</root>

$ fcat $URL/root/file3
filesystems inside XML?

Listing 5. example-rev.xsl

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet
  
  version="1.0"
  
  exclude-result-prefixes="ferris"
  >
  <xsl:output method="xml"/>

  <xsl:template match="/">
    <explicit-updates>
        <xsl:apply-templates/>
      </explicit-updates>
  </xsl:template>

  <xsl:template match="context[@name='file3']">
    <context url="{@original-url}">
      <xsl:value-of select="."/>
    </context>
  </xsl:template>

  <xsl:template match="context[@name='file7']">
    <attribute url="{@original-url}"
name="myattr"><xsl:value-of select="."/></attribute>
  </xsl:template>

</xsl:stylesheet>

Listing 6. Changing the XML File through our New XSLT Filesystem

$ bash
$ URL='xsltfs://context/file/tmp/example/
↪example.xml?stylesheet=example.xsl&
↪reverse-stylesheet=example-rev.xsl'
# Change the file3 element to have new content
$ echo foo | ferris-redirect -T $URL/root/file3
$ cat example.xml
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<root>
  <file1 size="200"/>
  <file3>foo
</file3>
  <file7 myattr="foo">Something blue</file7>
</root>

# Update everything based on a new XML file
$ cat example-update1.xml
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<root>
   <context name="file3" original-url=
↪"file:///tmp/example/example.xml/root/file3"
>A new file3 text node
   </context>
   <context name="file7" original-url=
↪"file:///tmp/example/example.xml/root/file7"
>A new file7 myattr</context>
</root>

$ cat example-update1.xml | ferris-redirect -T $URL

$ cat example.xml
<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<root>
  <file1 size="200"/>
  <file3>A new file3 text node
   </file3>
  <file7 myattr="A new file7 myattr"
>Something blue</file7>
</root>