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bpo-28238: Implement "{*}tag" and "{ns}*" wildcard tag selection support for ElementPath, and extend the surrounding tests and docs. (GH-12997)

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Stefan Behnel 2019-05-03 20:58:16 +02:00 committed by GitHub
parent cf48e55f7f
commit 47541689cc
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6 changed files with 171 additions and 15 deletions
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17
Doc/library/xml.etree.elementtree.rst
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@ -399,6 +399,12 @@ module. We'll be using the ``countrydata`` XML document from the
# All 'neighbor' nodes that are the second child of their parent
root.findall(".//neighbor[2]")
For XML with namespaces, use the usual qualified ``{namespace}tag`` notation::
# All dublin-core "title" tags in the document
root.findall(".//{http://purl.org/dc/elements/1.1/}title")
Supported XPath syntax
^^^^^^^^^^^^^^^^^^^^^^
@ -411,9 +417,16 @@ Supported XPath syntax
| | For example, ``spam`` selects all child elements |
| | named ``spam``, and ``spam/egg`` selects all |
| | grandchildren named ``egg`` in all children named |
| | ``spam``. |
| | ``spam``. ``{namespace}*`` selects all tags in the |
| | given namespace, ``{*}spam`` selects tags named |
| | ``spam`` in any (or no) namespace, and ``{}*`` |
| | only selects tags that are not in a namespace. |
| | |
| | .. versionchanged:: 3.8 |
| | Support for star-wildcards was added. |
+-----------------------+------------------------------------------------------+
| ``*`` | Selects all child elements. For example, ``*/egg`` |
| ``*`` | Selects all child elements, including comments and |
| | processing instructions. For example, ``*/egg`` |
| | selects all grandchildren named ``egg``. |
+-----------------------+------------------------------------------------------+
| ``.`` | Selects the current node. This is mostly useful |

5
Doc/whatsnew/3.8.rst
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@ -532,6 +532,11 @@ xml
external entities by default.
(Contributed by Christian Heimes in :issue:`17239`.)
* The ``.find*()`` methods in the :mod:`xml.etree.ElementTree` module
support wildcard searches like ``{*}tag`` which ignores the namespace
and ``{namespace}*`` which returns all tags in the given namespace.
(Contributed by Stefan Behnel in :issue:`28238`.)
* The :mod:`xml.etree.ElementTree` module provides a new function
:func:`–xml.etree.ElementTree.canonicalize()` that implements C14N 2.0.
(Contributed by Stefan Behnel in :issue:`13611`.)

56
Lib/test/test_xml_etree.py
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@ -1137,16 +1137,21 @@ class ElementTreeTest(unittest.TestCase):
def test_xpath_tokenizer(self):
# Test the XPath tokenizer.
from xml.etree import ElementPath
def check(p, expected):
def check(p, expected, namespaces=None):
self.assertEqual([op or tag
for op, tag in ElementPath.xpath_tokenizer(p)],
for op, tag in ElementPath.xpath_tokenizer(p, namespaces)],
expected)
# tests from the xml specification
check("*", ['*'])
check("{ns}*", ['{ns}*'])
check("{}*", ['{}*'])
check("{*}tag", ['{*}tag'])
check("{*}*", ['{*}*'])
check("text()", ['text', '()'])
check("@name", ['@', 'name'])
check("@*", ['@', '*'])
check("@{ns}attr", ['@', '{ns}attr'])
check("para[1]", ['para', '[', '1', ']'])
check("para[last()]", ['para', '[', 'last', '()', ']'])
check("*/para", ['*', '/', 'para'])
@ -1158,6 +1163,7 @@ class ElementTreeTest(unittest.TestCase):
check("//olist/item", ['//', 'olist', '/', 'item'])
check(".", ['.'])
check(".//para", ['.', '//', 'para'])
check(".//{*}tag", ['.', '//', '{*}tag'])
check("..", ['..'])
check("../@lang", ['..', '/', '@', 'lang'])
check("chapter[title]", ['chapter', '[', 'title', ']'])
@ -1168,6 +1174,8 @@ class ElementTreeTest(unittest.TestCase):
check("{http://spam}egg", ['{http://spam}egg'])
check("./spam.egg", ['.', '/', 'spam.egg'])
check(".//{http://spam}egg", ['.', '//', '{http://spam}egg'])
check("./xsd:type", ['.', '/', '{http://www.w3.org/2001/XMLSchema}type'],
{'xsd': 'http://www.w3.org/2001/XMLSchema'})
def test_processinginstruction(self):
# Test ProcessingInstruction directly
@ -2669,6 +2677,50 @@ class ElementFindTest(unittest.TestCase):
self.assertEqual(len(root.findall(".//xx:b", namespaces=nsmap)), 2)
self.assertEqual(len(root.findall(".//b", namespaces=nsmap)), 1)
def test_findall_wildcard(self):
root = ET.XML('''
<a xmlns:x="X" xmlns:y="Y">
<x:b><c/></x:b>
<b/>
<c><x:b/><b/></c><y:b/>
</a>''')
root.append(ET.Comment('test'))
self.assertEqual(summarize_list(root.findall("{*}b")),
['{X}b', 'b', '{Y}b'])
self.assertEqual(summarize_list(root.findall("{*}c")),
['c'])
self.assertEqual(summarize_list(root.findall("{X}*")),
['{X}b'])
self.assertEqual(summarize_list(root.findall("{Y}*")),
['{Y}b'])
self.assertEqual(summarize_list(root.findall("{}*")),
['b', 'c'])
self.assertEqual(summarize_list(root.findall("{}b")), # only for consistency
['b'])
self.assertEqual(summarize_list(root.findall("{}b")),
summarize_list(root.findall("b")))
self.assertEqual(summarize_list(root.findall("{*}*")),
['{X}b', 'b', 'c', '{Y}b'])
# This is an unfortunate difference, but that's how find('*') works.
self.assertEqual(summarize_list(root.findall("{*}*") + [root[-1]]),
summarize_list(root.findall("*")))
self.assertEqual(summarize_list(root.findall(".//{*}b")),
['{X}b', 'b', '{X}b', 'b', '{Y}b'])
self.assertEqual(summarize_list(root.findall(".//{*}c")),
['c', 'c'])
self.assertEqual(summarize_list(root.findall(".//{X}*")),
['{X}b', '{X}b'])
self.assertEqual(summarize_list(root.findall(".//{Y}*")),
['{Y}b'])
self.assertEqual(summarize_list(root.findall(".//{}*")),
['c', 'b', 'c', 'b'])
self.assertEqual(summarize_list(root.findall(".//{}b")), # only for consistency
['b', 'b'])
self.assertEqual(summarize_list(root.findall(".//{}b")),
summarize_list(root.findall(".//b")))
def test_bad_find(self):
e = ET.XML(SAMPLE_XML)
with self.assertRaisesRegex(SyntaxError, 'cannot use absolute path'):

70
Lib/xml/etree/ElementPath.py
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@ -99,8 +99,65 @@ def get_parent_map(context):
parent_map[e] = p
return parent_map
def _is_wildcard_tag(tag):
return tag[:3] == '{*}' or tag[-2:] == '}*'
def _prepare_tag(tag):
_isinstance, _str = isinstance, str
if tag == '{*}*':
# Same as '*', but no comments or processing instructions.
# It can be a surprise that '*' includes those, but there is no
# justification for '{*}*' doing the same.
def select(context, result):
for elem in result:
if _isinstance(elem.tag, _str):
yield elem
elif tag == '{}*':
# Any tag that is not in a namespace.
def select(context, result):
for elem in result:
el_tag = elem.tag
if _isinstance(el_tag, _str) and el_tag[0] != '{':
yield elem
elif tag[:3] == '{*}':
# The tag in any (or no) namespace.
suffix = tag[2:] # '}name'
no_ns = slice(-len(suffix), None)
tag = tag[3:]
def select(context, result):
for elem in result:
el_tag = elem.tag
if el_tag == tag or _isinstance(el_tag, _str) and el_tag[no_ns] == suffix:
yield elem
elif tag[-2:] == '}*':
# Any tag in the given namespace.
ns = tag[:-1]
ns_only = slice(None, len(ns))
def select(context, result):
for elem in result:
el_tag = elem.tag
if _isinstance(el_tag, _str) and el_tag[ns_only] == ns:
yield elem
else:
raise RuntimeError(f"internal parser error, got {tag}")
return select
def prepare_child(next, token):
tag = token[1]
if _is_wildcard_tag(tag):
select_tag = _prepare_tag(tag)
def select(context, result):
def select_child(result):
for elem in result:
yield from elem
return select_tag(context, select_child(result))
else:
if tag[:2] == '{}':
tag = tag[2:] # '{}tag' == 'tag'
def select(context, result):
for elem in result:
for e in elem:
@ -130,6 +187,19 @@ def prepare_descendant(next, token):
tag = token[1]
else:
raise SyntaxError("invalid descendant")
if _is_wildcard_tag(tag):
select_tag = _prepare_tag(tag)
def select(context, result):
def select_child(result):
for elem in result:
for e in elem.iter():
if e is not elem:
yield e
return select_tag(context, select_child(result))
else:
if tag[:2] == '{}':
tag = tag[2:] # '{}tag' == 'tag'
def select(context, result):
for elem in result:
for e in elem.iter(tag):

3
Misc/NEWS.d/next/Library/2019-04-28-15-01-29.bpo-28238.gdk38f.rst Normal file
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@ -0,0 +1,3 @@
The ``.find*()`` methods of xml.etree.ElementTree can now search for
wildcards like ``{*}tag`` and ``{ns}*`` that match a tag in any namespace
or all tags in a namespace. Patch by Stefan Behnel.

15
Modules/_elementtree.c
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@ -1149,6 +1149,13 @@ checkpath(PyObject* tag)
const Py_ssize_t len = PyUnicode_GET_LENGTH(tag);
void *data = PyUnicode_DATA(tag);
unsigned int kind = PyUnicode_KIND(tag);
if (len >= 3 && PyUnicode_READ(kind, data, 0) == '{' && (
PyUnicode_READ(kind, data, 1) == '}' || (
PyUnicode_READ(kind, data, 1) == '*' &&
PyUnicode_READ(kind, data, 2) == '}'))) {
/* wildcard: '{}tag' or '{*}tag' */
return 1;
}
for (i = 0; i < len; i++) {
Py_UCS4 ch = PyUnicode_READ(kind, data, i);
if (ch == '{')
@ -1162,7 +1169,13 @@ checkpath(PyObject* tag)
}
if (PyBytes_Check(tag)) {
char *p = PyBytes_AS_STRING(tag);
for (i = 0; i < PyBytes_GET_SIZE(tag); i++) {
const Py_ssize_t len = PyBytes_GET_SIZE(tag);
if (len >= 3 && p[0] == '{' && (
p[1] == '}' || p[1] == '*' && p[2] == '}')) {
/* wildcard: '{}tag' or '{*}tag' */
return 1;
}
for (i = 0; i < len; i++) {
if (p[i] == '{')
check = 0;
else if (p[i] == '}')