https://github.com/python/cpython/commit/a76d9573e45dc11cb0909154fa3e68591dfab85f
commit: a76d9573e45dc11cb0909154fa3e68591dfab85f
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2026-05-05T11:25:22+03:00
summary:
gh-139489: Add xml.is_valid_name() (GH-139768)
It allows to check whether a string can be used as an element or attribute
name in XML.
files:
A Lib/test/test_xml.py
A Lib/xml/utils.py
A Misc/NEWS.d/next/Library/2025-10-08-15-36-00.gh-issue-139489.W46tvn.rst
M Doc/library/xml.rst
M Doc/whatsnew/3.15.rst
M Lib/xml/__init__.py
diff --git a/Doc/library/xml.rst b/Doc/library/xml.rst
index a47d31465b19f1..f9ffaa9a94aacc 100644
--- a/Doc/library/xml.rst
+++ b/Doc/library/xml.rst
@@ -41,6 +41,21 @@ The XML handling submodules are:
* :mod:`xml.sax`: SAX2 base classes and convenience functions
* :mod:`xml.parsers.expat`: the Expat parser binding
+This module also defines utility functions.
+
+.. function:: is_valid_name(name)
+
+ Return ``True`` if the string is a valid element or attribute name,
+ ``False`` otherwise.
+
+ Almost all characters are permitted in names, except control characters and
+ those which either are or reasonably could be used as delimiters.
+ Characters like ":", "-", ".", "_", and "·" are permitted, but "<", "/",
+ "!", "?", and "=" are forbidden.
+ The name cannot start with a digit or a character like "-", ".", and "·".
+
+ ..versionadded:: next
+
.. _xml-security:
.. _xml-vulnerabilities:
diff --git a/Doc/whatsnew/3.15.rst b/Doc/whatsnew/3.15.rst
index 4f83916e3b77c2..828bc1d1d64d0a 100644
--- a/Doc/whatsnew/3.15.rst
+++ b/Doc/whatsnew/3.15.rst
@@ -1653,6 +1653,14 @@ wave
(Contributed by Lionel Koenig and Michiel W. Beijen in :gh:`60729`.)
+xml
+---
+
+* Add the :func:`xml.is_valid_name` function, which allows to check
+ whether a string can be used as an element or attribute name in XML.
+ (Contributed by Serhiy Storchaka in :gh:`139489`.)
+
+
xml.parsers.expat
-----------------
diff --git a/Lib/test/test_xml.py b/Lib/test/test_xml.py
new file mode 100644
index 00000000000000..fd3633e43982d7
--- /dev/null
+++ b/Lib/test/test_xml.py
@@ -0,0 +1,27 @@
+import xml
+import unittest
+
+
+class TestUtils(unittest.TestCase):
+
+ def test_is_valid_name(self):
+ is_valid_name = xml.is_valid_name
+ self.assertFalse(is_valid_name(''))
+ self.assertTrue(is_valid_name('name'))
+ self.assertTrue(is_valid_name('NAME'))
+ self.assertTrue(is_valid_name('name0:-._·'))
+ self.assertTrue(is_valid_name('_'))
+ self.assertTrue(is_valid_name(':'))
+ self.assertTrue(is_valid_name('Ñàḿĕ'))
+ self.assertTrue(is_valid_name('\U000EFFFF'))
+ self.assertFalse(is_valid_name('0'))
+ self.assertFalse(is_valid_name('-'))
+ self.assertFalse(is_valid_name('.'))
+ self.assertFalse(is_valid_name('·'))
+ self.assertFalse(is_valid_name('na me'))
+ for c in '<>/!?=\x00\x01\x7f\ud800\udfff\ufffe\uffff\U000F0000':
+ self.assertFalse(is_valid_name('name' + c))
+
+
+if __name__ == '__main__':
+ unittest.main()
diff --git a/Lib/xml/__init__.py b/Lib/xml/__init__.py
index bf6d8ddfd04c93..002d6d3e0e8267 100644
--- a/Lib/xml/__init__.py
+++ b/Lib/xml/__init__.py
@@ -16,5 +16,6 @@
"""
+from .utils import *
-__all__ = ["dom", "parsers", "sax", "etree"]
+__all__ = ["dom", "parsers", "sax", "etree", "is_valid_name"]
diff --git a/Lib/xml/utils.py b/Lib/xml/utils.py
new file mode 100644
index 00000000000000..c9a0b260675bed
--- /dev/null
+++ b/Lib/xml/utils.py
@@ -0,0 +1,25 @@
+lazy import re as _re
+
+
+def is_valid_name(name):
+ """Test whether a string is a valid element or attribute name."""
+ # https://www.w3.org/TR/xml/#NT-Name
+ return _re.fullmatch(
+ # NameStartChar
+ '['
+ ':A-Z_a-z'
+ '\xC0-\xD6\xD8-\xF6\xF8-\u02FF\u0370-\u037D\u037F-\u1FFF'
+ '\u200C\u200D'
+ '\u2070-\u218F\u2C00-\u2FEF\u3001-\uD7FF'
+ '\uF900-\uFDCF\uFDF0-\uFFFD\U00010000-\U000EFFFF'
+ ']'
+ # NameChar
+ '['
+ r'\-.0-9:A-Z_a-z'
+ '\xB7'
+ '\xC0-\xD6\xD8-\xF6\xF8-\u037D\u037F-\u1FFF'
+ '\u200C\u200D\u203F\u2040'
+ '\u2070-\u218F\u2C00-\u2FEF\u3001-\uD7FF'
+ '\uF900-\uFDCF\uFDF0-\uFFFD\U00010000-\U000EFFFF'
+ ']*+',
+ name) is not None
diff --git
a/Misc/NEWS.d/next/Library/2025-10-08-15-36-00.gh-issue-139489.W46tvn.rst
b/Misc/NEWS.d/next/Library/2025-10-08-15-36-00.gh-issue-139489.W46tvn.rst
new file mode 100644
index 00000000000000..05edefda053a08
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-10-08-15-36-00.gh-issue-139489.W46tvn.rst
@@ -0,0 +1,2 @@
+Add the :func:`xml.is_valid_name` function, which allows to check
+whether a string can be used as an element or attribute name in XML.
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