[libxslt] Add the saxon:systemId extension

[Daniel Veillard <veillard src gnome org>]

commit 92bc8136311ed86d85f764cbfc82da77d90c0e29
Author: Mike Hommey <mh glandium org>
Date:   Wed Sep 12 11:07:56 2012 +0800

    Add the saxon:systemId extension
    
    For https://bugzilla.gnome.org/show_bug.cgi?id=519926
    
    Both Xalan and Saxon have a systemId function (in their respective
    namespaces) to provide the URI of the file that is being transformed.
    It would be nice to have that function in libxslt1.1 as well, because
    then DocBook could use it[0].
    
    [0] See line 250 et seq in
    /usr/share/xml/docbook/stylesheet/nwalsh/common/stripns.xsl

 libexslt/saxon.c |   29 +++++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)
---
diff --git a/libexslt/saxon.c b/libexslt/saxon.c
index fcb1547..60880c8 100644
--- a/libexslt/saxon.c
+++ b/libexslt/saxon.c
@@ -180,6 +180,32 @@ exsltSaxonEvaluateFunction (xmlXPathParserContextPtr ctxt, int nargs) {
 }
 
 /**
+ * exsltSaxonSystemIdFunction:
+ * @ctxt:  an XPath parser context
+ * @nargs: number of arguments
+ *
+ * Implements the SAXON systemId() function
+ *     string saxon:systemId ()
+ * This function returns the system ID of the document being styled.
+ */
+static void
+exsltSaxonSystemIdFunction(xmlXPathParserContextPtr ctxt, int nargs)
+{
+    if (ctxt == NULL)
+        return;
+    if (nargs != 0) {
+        xmlXPathSetArityError(ctxt);
+        return;
+    }
+
+    if ((ctxt->context) && (ctxt->context->doc) &&
+        (ctxt->context->doc->URL))
+	valuePush(ctxt, xmlXPathNewString(ctxt->context->doc->URL));
+    else
+	valuePush(ctxt, xmlXPathNewString(BAD_CAST ""));
+}
+
+/**
  * exsltSaxonLineNumberFunction:
  * @ctxt:  an XPath parser context
  * @nargs: number of arguments
@@ -264,4 +290,7 @@ exsltSaxonRegister (void) {
     xsltRegisterExtModuleFunction ((const xmlChar *) "line-number",
 				   SAXON_NAMESPACE,
 				   exsltSaxonLineNumberFunction);
+    xsltRegisterExtModuleFunction ((const xmlChar *) "systemId",
+				   SAXON_NAMESPACE,
+				   exsltSaxonSystemIdFunction);
 }