Introduce XPath function to convert to upper/lower case.

antidox/templates/compound.xsl

@@ -83,7 +83,7 @@
         <xsl:param name="key-word" select="name"/>
         <xsl:if test="not($noindex)">
             <antidox:index>
-                <xsl:attribute name="key"><xsl:value-of select="substring($key-word, 1, 1)"/></xsl:attribute>
+                <xsl:attribute name="key"><xsl:value-of select="antidox:upper-case(substring($key-word, 1, 1))"/></xsl:attribute>
             </antidox:index>
         </xsl:if>
     </xsl:template>

antidox/xtransform.py

@@ -42,6 +42,18 @@ def _f(ctx, nodes_or_text):
 _basic_ns = ET.FunctionNamespace("antidox")
 
 
+@_basic_ns("upper-case")
+@_textfunc
+def _upper_case(text):
+    return text.upper()
+
+
+@_basic_ns("lower-case")
+@_textfunc
+def _lower_case(text):
+    return text.lower()
+
+
 @_basic_ns("string-to-ids")
 @_textfunc
 def _string_to_ids(text):

doc/source/templating.rst

@@ -115,6 +115,16 @@ XPath extension functions
     the "initial" letter correctly for the index.
 
 
+.. xpath-func:: antidox:lower-case(node_or_text)
+
+  Convert text to lower-case (similar to the same name function in XPath 2.0.)
+
+
+.. xpath-func:: antidox:upper-case(node_or_text)
+
+  Convert text to upper-case (similar to the same name function in XPath 2.0.)
+
+
 antidox-specific (pseudo)elements
 ---------------------------------