XSLT: Convert Standard U.S. Date into xsd:date Format

When working with XML in the United States (U.S.), one will often find dates which have been formatted in the traditional U.S. Short Format even though XML Schema (XSD) enforces a more locale-neutral format.  This means often converting data from:

<SomeUsDate>1/10/2001</SomeUsDate>

Into:

<SomeXsdDate>2001-01-10</SomeXsdDate>

If one is using XSLT 2.0, this can simply be done by including and calling the function within the FunctX library here. 

In XSLT 1.0, a very limited set of string manipulation functionality exists. Even so, it is possible (although convoluted) to convert a typical U.S.-formatted date into an XML-Schema enforced date. A possible solution is listed below:

<xsl:template name="aoc:txfDateFormat">
         <xsl:param name="UsDate"/>

         <xsl:choose>

             <!-- Test to see if date contains a date with slashes in it. -->
             <xsl:when test="contains($UsDate, '/')">
                 <xsl:choose>

                     <!-- 2 Digit Month, 2 Digit Day -->
                     <xsl:when
                         test="string-length(substring-before($UsDate, '/'))=2 and (string-length(substring-before(substring-after($UsDate, '/'), '/'))=2)">
                         <nc:Date>
                             <xsl:value-of
                                 select="concat(substring-after(substring-after($UsDate, '/'), '/'),'-',substring-before($UsDate, '/'), '-', substring-before(substring-after($UsDate, '/'), '/'))"
                             />
                         </nc:Date>
                     </xsl:when>

                     <!-- 1 Digit Month, 2 Digit Day -->
                     <xsl:when
                         test="string-length(substring-before($UsDate, '/'))=1 and (string-length(substring-before(substring-after($UsDate, '/'), '/'))=2)">
                         <nc:Date>
                             <xsl:value-of
                                 select="concat(substring-after(substring-after($UsDate, '/'), '/'),'-0',substring-before($UsDate, '/'), '-', substring-before(substring-after($UsDate, '/'), '/'))"
                             />
                         </nc:Date>
                     </xsl:when>

                     <!-- 2 Digit Month, 1 Digit Day -->
                     <xsl:when
                         test="string-length(substring-before($UsDate, '/'))=2 and (string-length(substring-before(substring-after($UsDate, '/'), '/'))=1)">
                         <nc:Date>
                             <xsl:value-of
                                 select="concat(substring-after(substring-after($UsDate, '/'), '/'),'-',substring-before($UsDate, '/'), '-0', substring-before(substring-after($UsDate, '/'), '/'))"
                             />
                         </nc:Date>
                     </xsl:when>

                     <!-- 1 Digit Month, 1 Digit Day -->
                     <xsl:when
                         test="string-length(substring-before($UsDate, '/'))=1 and (string-length(substring-before(substring-after($UsDate, '/'), '/'))=1)">
                         <nc:Date>
                             <xsl:value-of
                                 select="concat(substring-after(substring-after($UsDate, '/'), '/'),'-0',substring-before($UsDate, '/'), '-0', substring-before(substring-after($UsDate, '/'), '/'))"
                             />
                         </nc:Date>
                     </xsl:when>
                 </xsl:choose>
             </xsl:when>

             <!-- Omit element if not. -->
             <xsl:otherwise/>
         </xsl:choose>
   </xsl:template>