XSLT Hex to Decimal Conversion

Here’s a trick I came up with to convert some XML values from hex to decimal.

I made clever (awful?) use of substring-after and substring-before and a string-based lookup table.

Very nasty, but with whats available, very neat:

  <!-- output $hexNumber as decimal, recursive so not too many digits please... -->
  <xsl:template name="HexToDecimal">
    <xsl:param name="hexNumber" />
    <xsl:param name="decimalNumber" >0</xsl:param>
    <!– If there is zero hex digits left, output –>
    <xsl:choose>
      <xsl:when test="$hexNumber">
        <xsl:call-template name="HexToDecimal">
          <xsl:with-param name="decimalNumber" select="($decimalNumber*16)+number(substring-before(substring-after(’00/11/22/33/44/55/66/77/88/99/A10/B11/C12/D13/E14/F15/a10/b11/c12/d13/e14/f15/’,substring($hexNumber,1,1)),’/'))" />
          <xsl:with-param name="hexNumber" select="substring($hexNumber,2)" />
        </xsl:call-template>
      </xsl:when>
      <!– otherwise multiply, and add the next digit, and recurse –>
      <xsl:otherwise>
        <xsl:value-of select="$decimalNumber"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>
  <!– If it begins with 0x then parse it for sure, else return it –>
  <xsl:template name="asDecimal">
    <xsl:param name="number" />
    <xsl:choose>
      <xsl:when test="substring($number,1,2)=’0x’">
        <xsl:call-template name="HexToDecimal">
          <xsl:with-param name="hexNumber" select="substring($number,3)"/>
        </xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <xsl:value-of select="$number"/>
      </xsl:otherwise>
    </xsl:choose>
  </xsl:template>

Invoke with
  <xsl:call-template name="HexToDecimal">
    <xsl:with-param name="hexNumber" select="@hexValueAttribute"/>
  </xsl:call-template>

Or some such