Is it possible to flip and rotate text using XSLT?

Question

I would like to take the contents of an XML tag and have it displayed flipped both horizontally (mirror image) and vertically (as a column) when viewed through a stylesheet. Is this possible without using random third party libraries?

<mytag>Random Data</mytag>

Answer 1

As such, XSLT is ill-suited for string processing. With XSLT 2.0, things get better since more string functions are available, and sequence-based operations are possible.

In XSLT 1.0 (which is still the most portable version to write code for), character-by-character string processing can only be achieved through recursion. For the fun of it, this:

<xsl:output method="text" />

<xsl:variable name="CRLF" select="'&#13;&#10;'" />

<xsl:template match="/mytag">
  <!-- flip string -->
  <xsl:call-template name="reverse-string">
    <xsl:with-param name="s" select="string(.)" />
  </xsl:call-template>
  <xsl:value-of select="$CRLF" />

  <!-- vertical string -->
  <xsl:call-template name="vertical-string">
    <xsl:with-param name="s" select="string(.)" />
  </xsl:call-template>
</xsl:template>

<xsl:template name="reverse-string">
  <xsl:param name="s" select="''" />

  <xsl:variable name="l" select="string-length($s)" />

  <xsl:value-of select="substring($s, $l, 1)" />

  <xsl:if test="$l &gt; 0">
    <xsl:call-template name="reverse-string">
      <xsl:with-param name="s" select="substring($s, 1, $l - 1)" />
    </xsl:call-template>
  </xsl:if>
</xsl:template>

<xsl:template name="vertical-string">
  <xsl:param name="s" select="''" />

  <xsl:variable name="l" select="string-length($s)" />

  <xsl:value-of select="concat(substring($s, 1, 1), $CRLF)" />

  <xsl:if test="$l &gt; 0">
    <xsl:call-template name="vertical-string">
      <xsl:with-param name="s" select="substring($s, 2, $l)" />
    </xsl:call-template>
  </xsl:if>
</xsl:template>

Produces:

ataD modnaR
R
a
n
d
o
m

D
a
t
a

EDIT: To be clear: I do not endorse actual use of the above code sample in any way. Presentational issues should by all means be solved in the presentation layer. The above will work, but char-by-char recursion is among the most inefficient ways to do string processing, and unless you have no other choice, avoid string processing in XSLT.