Find all namespace declarations in an XML document - xPath 1.0 vs xPath 2.0

Question

As part of a Java 6 application, I want to find all namespace declarations in an XML document, including any duplicates.

Edit: Per Martin\'s request, h

Answer 1

To find all namespace declarations, I applied this xPath statement to the XML document using xPath 1.0:

//namespace::* It finds 4 namespace declarations, which is what I expect (and desire):

/root[1]/@xmlns:att - attribute.com
/root[1]/@xmlns:ele - element.com 
/root[1]/@xmlns:txt - textnode.com 
/root[1]/@xmlns:xml - http://www.w3.org/XML/1998/namespace

You are using a non-compliant (buggy) XPath 1.0 implementation.

I get different and correct results with all XSLT 1.0 processors I have. This transformation (just evaluating the XPath expression and printing one line for each selected namespace node):

when applied on the provided XML document:

    a
    e
    txt:f

produces a correct result:

xml: http://www.w3.org/XML/1998/namespace
ele: element.com
att: attribute.com
txt: textnode.com
xml: http://www.w3.org/XML/1998/namespace
ele: element.com
att: attribute.com
txt: textnode.com
xml: http://www.w3.org/XML/1998/namespace
ele: element.com
att: attribute.com
txt: textnode.com
xml: http://www.w3.org/XML/1998/namespace
ele: element.com
att: attribute.com
txt: textnode.com

with all of these XSLT 1.0 and XSLT 2.0 processors:

MSXML3, MSXML4, MSXML6, .NET XslCompiledTransform, .NET XslTransform, Altova (XML SPY), Saxon 6.5.4, Saxon 9.1.07, XQSharp.

Here is a short C# program that confirms the number of nodes selected in .NET is 16:

namespace TestNamespaces
{
    using System;
    using System.IO;
    using System.Xml.XPath;

    class Test
    {
        static void Main(string[] args)
        {
            string xml =
@"
    a
    e
    txt:f
";
            XPathDocument doc = new XPathDocument(new StringReader(xml));

            double count = 
              (double) doc.CreateNavigator().Evaluate("count(//namespace::*)");

            Console.WriteLine(count);
        }
    }
}

The result is:

16.

UPDATE:

This is an XPath 2.0 expression that finds just the "distinct" namespace nodes and produces a line of name - value pairs for each of them:

for $i in distinct-values(
             for $ns in //namespace::*
               return
                  index-of(
                           (for $x in //namespace::*
                             return
                                concat(name($x), ' ', string($x))

                            ),
                            concat(name($ns), ' ', string($ns))
                          )
                          [1]
                                                  )
  return
    for $x in (//namespace::*)[$i]
     return
        concat(name($x), ' :', string($x), '
')