[Python-checkins] gh-99029: Fix handling of `PureWindowsPath('C:\<blah>').relative_to('C:')` (GH-99031)
brettcannon
webhook-mailer at python.org
Fri Nov 25 14:16:02 EST 2022
https://github.com/python/cpython/commit/ae234fbc5ce045066448f2f0cda2f1c3c7ddebea
commit: ae234fbc5ce045066448f2f0cda2f1c3c7ddebea
branch: main
author: Barney Gale <barney.gale at gmail.com>
committer: brettcannon <brett at python.org>
date: 2022-11-25T11:15:57-08:00
summary:
gh-99029: Fix handling of `PureWindowsPath('C:\<blah>').relative_to('C:')` (GH-99031)
`relative_to()` now treats naked drive paths as relative. This brings its
behaviour in line with other parts of pathlib, and with `ntpath.relpath()`,
and so allows us to factor out the pathlib-specific implementation.
files:
A Misc/NEWS.d/next/Library/2022-11-02-23-47-07.gh-issue-99029.7uCiIB.rst
M Lib/pathlib.py
M Lib/test/test_pathlib.py
diff --git a/Lib/pathlib.py b/Lib/pathlib.py
index bc57ae60e725..f31eb3010368 100644
--- a/Lib/pathlib.py
+++ b/Lib/pathlib.py
@@ -632,57 +632,27 @@ def relative_to(self, *other, walk_up=False):
The *walk_up* parameter controls whether `..` may be used to resolve
the path.
"""
- # For the purpose of this method, drive and root are considered
- # separate parts, i.e.:
- # Path('c:/').relative_to('c:') gives Path('/')
- # Path('c:/').relative_to('/') raise ValueError
if not other:
raise TypeError("need at least one argument")
- parts = self._parts
- drv = self._drv
- root = self._root
- if root:
- abs_parts = [drv, root] + parts[1:]
- else:
- abs_parts = parts
- other_drv, other_root, other_parts = self._parse_args(other)
- if other_root:
- other_abs_parts = [other_drv, other_root] + other_parts[1:]
- else:
- other_abs_parts = other_parts
- num_parts = len(other_abs_parts)
- casefold = self._flavour.casefold_parts
- num_common_parts = 0
- for part, other_part in zip(casefold(abs_parts), casefold(other_abs_parts)):
- if part != other_part:
+ path_cls = type(self)
+ other = path_cls(*other)
+ for step, path in enumerate([other] + list(other.parents)):
+ if self.is_relative_to(path):
break
- num_common_parts += 1
- if walk_up:
- failure = root != other_root
- if drv or other_drv:
- failure = casefold([drv]) != casefold([other_drv]) or (failure and num_parts > 1)
- error_message = "{!r} is not on the same drive as {!r}"
- up_parts = (num_parts-num_common_parts)*['..']
else:
- failure = (root or drv) if num_parts == 0 else num_common_parts != num_parts
- error_message = "{!r} is not in the subpath of {!r}"
- up_parts = []
- error_message += " OR one path is relative and the other is absolute."
- if failure:
- formatted = self._format_parsed_parts(other_drv, other_root, other_parts)
- raise ValueError(error_message.format(str(self), str(formatted)))
- path_parts = up_parts + abs_parts[num_common_parts:]
- new_root = root if num_common_parts == 1 else ''
- return self._from_parsed_parts('', new_root, path_parts)
+ raise ValueError(f"{str(self)!r} and {str(other)!r} have different anchors")
+ if step and not walk_up:
+ raise ValueError(f"{str(self)!r} is not in the subpath of {str(other)!r}")
+ parts = ('..',) * step + self.parts[len(path.parts):]
+ return path_cls(*parts)
def is_relative_to(self, *other):
"""Return True if the path is relative to another path or False.
"""
- try:
- self.relative_to(*other)
- return True
- except ValueError:
- return False
+ if not other:
+ raise TypeError("need at least one argument")
+ other = type(self)(*other)
+ return other == self or other in self.parents
@property
def parts(self):
diff --git a/Lib/test/test_pathlib.py b/Lib/test/test_pathlib.py
index 94401e5429cd..1d01d3cbd91d 100644
--- a/Lib/test/test_pathlib.py
+++ b/Lib/test/test_pathlib.py
@@ -1183,10 +1183,6 @@ def test_relative_to(self):
self.assertRaises(ValueError, p.relative_to, P('/Foo'), walk_up=True)
self.assertRaises(ValueError, p.relative_to, P('C:/Foo'), walk_up=True)
p = P('C:/Foo/Bar')
- self.assertEqual(p.relative_to(P('c:')), P('/Foo/Bar'))
- self.assertEqual(p.relative_to('c:'), P('/Foo/Bar'))
- self.assertEqual(str(p.relative_to(P('c:'))), '\\Foo\\Bar')
- self.assertEqual(str(p.relative_to('c:')), '\\Foo\\Bar')
self.assertEqual(p.relative_to(P('c:/')), P('Foo/Bar'))
self.assertEqual(p.relative_to('c:/'), P('Foo/Bar'))
self.assertEqual(p.relative_to(P('c:/foO')), P('Bar'))
@@ -1194,10 +1190,6 @@ def test_relative_to(self):
self.assertEqual(p.relative_to('c:/foO/'), P('Bar'))
self.assertEqual(p.relative_to(P('c:/foO/baR')), P())
self.assertEqual(p.relative_to('c:/foO/baR'), P())
- self.assertEqual(p.relative_to(P('c:'), walk_up=True), P('/Foo/Bar'))
- self.assertEqual(p.relative_to('c:', walk_up=True), P('/Foo/Bar'))
- self.assertEqual(str(p.relative_to(P('c:'), walk_up=True)), '\\Foo\\Bar')
- self.assertEqual(str(p.relative_to('c:', walk_up=True)), '\\Foo\\Bar')
self.assertEqual(p.relative_to(P('c:/'), walk_up=True), P('Foo/Bar'))
self.assertEqual(p.relative_to('c:/', walk_up=True), P('Foo/Bar'))
self.assertEqual(p.relative_to(P('c:/foO'), walk_up=True), P('Bar'))
@@ -1209,6 +1201,8 @@ def test_relative_to(self):
self.assertEqual(p.relative_to('C:/Foo/Bar/Baz', walk_up=True), P('..'))
self.assertEqual(p.relative_to('C:/Foo/Baz', walk_up=True), P('../Bar'))
# Unrelated paths.
+ self.assertRaises(ValueError, p.relative_to, 'c:')
+ self.assertRaises(ValueError, p.relative_to, P('c:'))
self.assertRaises(ValueError, p.relative_to, P('C:/Baz'))
self.assertRaises(ValueError, p.relative_to, P('C:/Foo/Bar/Baz'))
self.assertRaises(ValueError, p.relative_to, P('C:/Foo/Baz'))
@@ -1218,6 +1212,8 @@ def test_relative_to(self):
self.assertRaises(ValueError, p.relative_to, P('/'))
self.assertRaises(ValueError, p.relative_to, P('/Foo'))
self.assertRaises(ValueError, p.relative_to, P('//C/Foo'))
+ self.assertRaises(ValueError, p.relative_to, 'c:', walk_up=True)
+ self.assertRaises(ValueError, p.relative_to, P('c:'), walk_up=True)
self.assertRaises(ValueError, p.relative_to, P('C:Foo'), walk_up=True)
self.assertRaises(ValueError, p.relative_to, P('d:'), walk_up=True)
self.assertRaises(ValueError, p.relative_to, P('d:/'), walk_up=True)
@@ -1275,13 +1271,13 @@ def test_is_relative_to(self):
self.assertFalse(p.is_relative_to(P('C:Foo/Bar/Baz')))
self.assertFalse(p.is_relative_to(P('C:Foo/Baz')))
p = P('C:/Foo/Bar')
- self.assertTrue(p.is_relative_to('c:'))
self.assertTrue(p.is_relative_to(P('c:/')))
self.assertTrue(p.is_relative_to(P('c:/foO')))
self.assertTrue(p.is_relative_to('c:/foO/'))
self.assertTrue(p.is_relative_to(P('c:/foO/baR')))
self.assertTrue(p.is_relative_to('c:/foO/baR'))
# Unrelated paths.
+ self.assertFalse(p.is_relative_to('c:'))
self.assertFalse(p.is_relative_to(P('C:/Baz')))
self.assertFalse(p.is_relative_to(P('C:/Foo/Bar/Baz')))
self.assertFalse(p.is_relative_to(P('C:/Foo/Baz')))
diff --git a/Misc/NEWS.d/next/Library/2022-11-02-23-47-07.gh-issue-99029.7uCiIB.rst b/Misc/NEWS.d/next/Library/2022-11-02-23-47-07.gh-issue-99029.7uCiIB.rst
new file mode 100644
index 000000000000..0bfba5e1e326
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-11-02-23-47-07.gh-issue-99029.7uCiIB.rst
@@ -0,0 +1,2 @@
+:meth:`pathlib.PurePath.relative_to()` now treats naked Windows drive paths
+as relative. This brings its behaviour in line with other parts of pathlib.
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