added the possibility of returning nodesets from XPath extension functions

* python/types.c python/tests/Makefile.am python/tests/xpathret.py:
  added the possibility of returning nodesets from XPath extension
  functions written in Python
Daniel

python/tests/xpathret.py

@@ -0,0 +1,57 @@
+#!/usr/bin/python -u
+import sys
+import libxml2
+
+#memory debug specific
+libxml2.debugMemory(1)
+
+#
+# A document hosting the nodes returned from the extension function
+#
+mydoc = libxml2.newDoc("1.0")
+
+def foo(ctx, str):
+    global mydoc
+
+    #
+    # test returning a node set works as expected
+    #
+    parent = mydoc.newDocNode(None, 'p', None)
+    mydoc.addChild(parent)
+    node = mydoc.newDocText(str)
+    parent.addChild(node)
+    return [parent]
+
+doc = libxml2.parseFile("tst.xml")
+ctxt = doc.xpathNewContext()
+libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
+res = ctxt.xpathEval("foo('hello')")
+if type(res) != type([]):
+    print "Failed to return a nodeset"
+    sys.exit(1)
+if len(res) != 1:
+    print "Unexpected nodeset size"
+    sys.exit(1)
+node = res[0]
+if node.name != 'p':
+    print "Unexpected nodeset element result"
+    sys.exit(1)
+node = node.children
+if node.type != 'text':
+    print "Unexpected nodeset element children type"
+    sys.exit(1)
+if node.content != 'hello':
+    print "Unexpected nodeset element children content"
+    sys.exit(1)
+
+doc.freeDoc()
+mydoc.freeDoc()
+ctxt.xpathFreeContext()
+
+#memory debug specific
+libxml2.cleanupParser()
+if libxml2.debugMemory(1) == 0:
+    print "OK"
+else:
+    print "Memory leak %d bytes" % (libxml2.debugMemory(1))
+    libxml2.dumpMemory()