/*
 * call-seq:
 *   parse_stylesheet_doc(document)
 *
 * Parse a stylesheet from +document+.
 */
static VALUE parse_stylesheet_doc(VALUE klass, VALUE xmldocobj)
{
    xmlDocPtr xml, xml_cpy;
    VALUE errstr, exception;
    xsltStylesheetPtr ss ;
    Data_Get_Struct(xmldocobj, xmlDoc, xml);
    exsltRegisterAll();

    errstr = rb_str_new(0, 0);
    xsltSetGenericErrorFunc((void *)errstr, xslt_generic_error_handler);

    xml_cpy = xmlCopyDoc(xml, 1); /* 1 => recursive */
    ss = xsltParseStylesheetDoc(xml_cpy);

    xsltSetGenericErrorFunc(NULL, NULL);

    if (!ss) {
        xmlFreeDoc(xml_cpy);
        exception = rb_exc_new3(rb_eRuntimeError, errstr);
        rb_exc_raise(exception);
    }

    return Nokogiri_wrap_xslt_stylesheet(ss);
}