gh-54873: Add support for namespaces prefixes to xml.sax.expatreader

Doc/whatsnew/3.15.rst

@@ -1383,6 +1383,13 @@ xml.parsers.expat
   .. _billion laughs: https://en.wikipedia.org/wiki/Billion_laughs_attack
 
 
+xml.sax.expatreader
+-------------------
+
+* Add support for `namespace prefixes <https://www.w3.org/TR/xml-names/#dt-prefix>`_.
+  (Contributed by Yassir Karroum in :gh:`118317`.)
+
+
 zlib
 ----
 

Lib/test/test_sax.py

@@ -1,5 +1,4 @@
 # regression test for SAX 2.0
-
 from xml.sax import make_parser, ContentHandler, \
                     SAXException, SAXReaderNotAvailable, SAXParseException
 import unittest
@@ -13,7 +12,7 @@
                              XMLFilterBase, prepare_input_source
 from xml.sax.expatreader import create_parser
 from xml.sax.handler import (feature_namespaces, feature_external_ges,
-                             LexicalHandler)
+                             LexicalHandler, feature_namespace_prefixes)
 from xml.sax.xmlreader import InputSource, AttributesImpl, AttributesNSImpl
 from xml import sax
 from io import BytesIO, StringIO
@@ -1307,6 +1306,55 @@ def test_expat_locator_withinfo_nonascii(self):
         self.assertEqual(parser.getSystemId(), fname)
         self.assertEqual(parser.getPublicId(), None)
 
+    def test_qualified_names(self):
+
+        class Handler(ContentHandler):
+            def startElementNS(self, name, qname, attrs):
+                self.qname = qname
+
+        for xml_s, expected_qname in (
+            ("<Q:E xmlns:Q='http://example.org/testuri'/>", "Q:E"),
+            ("<E xmlns='http://example.org/testuri'/>", "E"),
+            ("<E />", "E"),
+        ):
+            parser = create_parser()
+            parser.setFeature(feature_namespaces, 1)
+            parser.setFeature(feature_namespace_prefixes, 1)
+
+            h = Handler()
+
+            parser.setContentHandler(h)
+            parser.parse(StringIO(xml_s))
+            self.assertEqual(h.qname, expected_qname)
+
+    def test_qualified_names_when_feature_not_set(self):
+
+        class Handler(ContentHandler):
+            def startElementNS(self, name, qname, attrs):
+                self.qname = qname
+
+        for xml_s in (
+                "<Q:E xmlns:Q='http://example.org/testuri'/>",
+                "<E xmlns='http://example.org/testuri'/>",
+                "<E />",
+        ):
+            parser = create_parser()
+            parser.setFeature(feature_namespaces, 1)
+
+            h = Handler()
+
+            parser.setContentHandler(h)
+            parser.parse(StringIO(xml_s))
+
+            self.assertIsNone(h.qname)
+
+    def test_namespace_prefixed_enabled_when_namespace_is_not(self):
+
+        parser = create_parser()
+        with self.assertRaises(SAXException):
+            parser.setFeature(feature_namespace_prefixes, 1)
+
+
 
 # ===========================================================================
 #

Lib/xml/sax/expatreader.py

@@ -89,6 +89,7 @@ def __init__(self, namespaceHandling=0, bufsize=2**16-20):
         self._entity_stack = []
         self._external_ges = 0
         self._interning = None
+        self._namespace_prefixes = 0
 
     # XMLReader methods
 
@@ -124,8 +125,9 @@ def getFeature(self, name):
             return self._namespaces
         elif name == feature_string_interning:
             return self._interning is not None
-        elif name in (feature_validation, feature_external_pes,
-                      feature_namespace_prefixes):
+        elif name == feature_namespace_prefixes:
+            return self._namespace_prefixes
+        elif name in (feature_validation, feature_external_pes):
             return 0
         elif name == feature_external_ges:
             return self._external_ges
@@ -154,9 +156,9 @@ def setFeature(self, name, state):
                 raise SAXNotSupportedException(
                     "expat does not read external parameter entities")
         elif name == feature_namespace_prefixes:
-            if state:
-                raise SAXNotSupportedException(
-                    "expat does not report namespace prefixes")
+            if state and not self._namespaces:
+                raise SAXException(f"{feature_namespace_prefixes} requires {feature_namespaces} to be enabled")
+            self._namespace_prefixes = state
         else:
             raise SAXNotRecognizedException(
                 "Feature '%s' not recognized" % name)
@@ -345,11 +347,14 @@ def start_element_ns(self, name, attrs):
         pair = name.split()
         if len(pair) == 1:
             # no namespace
+            elem_qname = name
             pair = (None, name)
         elif len(pair) == 3:
+            elem_qname = "%s:%s" % (pair[2], pair[1])
             pair = pair[0], pair[1]
         else:
             # default namespace
+            elem_qname = pair[1]
             pair = tuple(pair)
 
         newattrs = {}
@@ -372,7 +377,10 @@ def start_element_ns(self, name, attrs):
             newattrs[apair] = value
             qnames[apair] = qname
 
-        self._cont_handler.startElementNS(pair, None,
+        if not self._namespace_prefixes:
+            elem_qname = None
+
+        self._cont_handler.startElementNS(pair, elem_qname,
                                           AttributesNSImpl(newattrs, qnames))
 
     def end_element_ns(self, name):

Misc/NEWS.d/next/Library/2024-04-26-14-21-04.gh-issue-54873.vf2bfp.rst

@@ -0,0 +1,2 @@
+Backported namespaces prefixes support for xml.sax.expatreader from PyXML
+(0.8.4)