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Issue #10395: Added os.path.commonpath(). Implemented in posixpath and ntpath. 

Based on patch by Rafik Draoui.
This commit is contained in:
Serhiy Storchaka 2015-03-31 15:31:53 +03:00
parent dd83bd2f9c
commit 3822093143
7 changed files with 255 additions and 5 deletions
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19
Doc/library/os.path.rst
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@ -66,11 +66,24 @@ the :mod:`glob` module.)
empty string (``''``).
.. function:: commonpath(paths)
Return the longest common sub-path of each pathname in the sequence
*paths*. Raise ValueError if *paths* contains both absolute and relative
pathnames, or if *paths* is empty. Unlike :func:`commonprefix`, this
returns a valid path.
Availability: Unix, Windows
.. versionadded:: 3.5
.. function:: commonprefix(list)
Return the longest path prefix (taken character-by-character) that is a prefix
of all paths in *list*. If *list* is empty, return the empty string (``''``).
Note that this may return invalid paths because it works a character at a time.
Return the longest path prefix (taken character-by-character) that is a
prefix of all paths in *list*. If *list* is empty, return the empty string
(``''``). Note that this may return invalid paths because it works a
character at a time. To obtain a valid path, see :func:`commonpath`.
.. function:: dirname(path)

7
Doc/whatsnew/3.5.rst
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@ -370,6 +370,13 @@ os
* :class:`os.stat_result` now has a :attr:`~os.stat_result.st_file_attributes`
attribute on Windows. (Contributed by Ben Hoyt in :issue:`21719`.)
os.path
-------
* New :func:`~os.path.commonpath` function that extracts common path prefix.
Unlike the :func:`~os.path.commonprefix` function, it always returns a valid
patch. (Contributed by Rafik Draoui and Serhiy Storchaka in :issue:`10395`.)
pickle
------

63
Lib/ntpath.py
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@ -17,7 +17,7 @@ __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
"ismount", "expanduser","expandvars","normpath","abspath",
"splitunc","curdir","pardir","sep","pathsep","defpath","altsep",
"extsep","devnull","realpath","supports_unicode_filenames","relpath",
"samefile", "sameopenfile", "samestat",]
"samefile", "sameopenfile", "samestat", "commonpath"]
# strings representing various path-related bits and pieces
# These are primarily for export; internally, they are hardcoded.
@ -589,6 +589,67 @@ def relpath(path, start=None):
raise
# Return the longest common sub-path of the sequence of paths given as input.
# The function is case-insensitive and 'separator-insensitive', i.e. if the
# only difference between two paths is the use of '\' versus '/' as separator,
# they are deemed to be equal.
#
# However, the returned path will have the standard '\' separator (even if the
# given paths had the alternative '/' separator) and will have the case of the
# first path given in the sequence. Additionally, any trailing separator is
# stripped from the returned path.
def commonpath(paths):
"""Given a sequence of path names, returns the longest common sub-path."""
if not paths:
raise ValueError('commonpath() arg is an empty sequence')
if isinstance(paths[0], bytes):
sep = b'\\'
altsep = b'/'
curdir = b'.'
else:
sep = '\\'
altsep = '/'
curdir = '.'
try:
drivesplits = [splitdrive(p.replace(altsep, sep).lower()) for p in paths]
split_paths = [p.split(sep) for d, p in drivesplits]
try:
isabs, = set(p[:1] == sep for d, p in drivesplits)
except ValueError:
raise ValueError("Can't mix absolute and relative paths") from None
# Check that all drive letters or UNC paths match. The check is made only
# now otherwise type errors for mixing strings and bytes would not be
# caught.
if len(set(d for d, p in drivesplits)) != 1:
raise ValueError("Paths don't have the same drive")
drive, path = splitdrive(paths[0].replace(altsep, sep))
common = path.split(sep)
common = [c for c in common if c and c != curdir]
split_paths = [[c for c in s if c and c != curdir] for s in split_paths]
s1 = min(split_paths)
s2 = max(split_paths)
for i, c in enumerate(s1):
if c != s2[i]:
common = common[:i]
break
else:
common = common[:len(s1)]
prefix = drive + sep if isabs else drive
return prefix + sep.join(common)
except (TypeError, AttributeError):
genericpath._check_arg_types('commonpath', *paths)
raise
# determine if two files are in fact the same file
try:
# GetFinalPathNameByHandle is available starting with Windows 6.0.

45
Lib/posixpath.py
View File

@ -22,7 +22,8 @@ __all__ = ["normcase","isabs","join","splitdrive","split","splitext",
"ismount", "expanduser","expandvars","normpath","abspath",
"samefile","sameopenfile","samestat",
"curdir","pardir","sep","pathsep","defpath","altsep","extsep",
"devnull","realpath","supports_unicode_filenames","relpath"]
"devnull","realpath","supports_unicode_filenames","relpath",
"commonpath"]
# Strings representing various path-related bits and pieces.
# These are primarily for export; internally, they are hardcoded.
@ -455,3 +456,45 @@ def relpath(path, start=None):
except (TypeError, AttributeError, BytesWarning, DeprecationWarning):
genericpath._check_arg_types('relpath', path, start)
raise
# Return the longest common sub-path of the sequence of paths given as input.
# The paths are not normalized before comparing them (this is the
# responsibility of the caller). Any trailing separator is stripped from the
# returned path.
def commonpath(paths):
"""Given a sequence of path names, returns the longest common sub-path."""
if not paths:
raise ValueError('commonpath() arg is an empty sequence')
if isinstance(paths[0], bytes):
sep = b'/'
curdir = b'.'
else:
sep = '/'
curdir = '.'
try:
split_paths = [path.split(sep) for path in paths]
try:
isabs, = set(p[:1] == sep for p in paths)
except ValueError:
raise ValueError("Can't mix absolute and relative paths") from None
split_paths = [[c for c in s if c and c != curdir] for s in split_paths]
s1 = min(split_paths)
s2 = max(split_paths)
common = s1
for i, c in enumerate(s1):
if c != s2[i]:
common = s1[:i]
break
prefix = sep if isabs else sep[:0]
return prefix + sep.join(common)
except (TypeError, AttributeError):
genericpath._check_arg_types('commonpath', *paths)
raise

69
Lib/test/test_ntpath.py
View File

@ -330,6 +330,75 @@ class TestNtpath(unittest.TestCase):
tester('ntpath.relpath("/a/b", "/a/b")', '.')
tester('ntpath.relpath("c:/foo", "C:/FOO")', '.')
def test_commonpath(self):
def check(paths, expected):
tester(('ntpath.commonpath(%r)' % paths).replace('\\\\', '\\'),
expected)
def check_error(exc, paths):
self.assertRaises(exc, ntpath.commonpath, paths)
self.assertRaises(exc, ntpath.commonpath,
[os.fsencode(p) for p in paths])
self.assertRaises(ValueError, ntpath.commonpath, [])
check_error(ValueError, ['C:\\Program Files', 'Program Files'])
check_error(ValueError, ['C:\\Program Files', 'C:Program Files'])
check_error(ValueError, ['\\Program Files', 'Program Files'])
check_error(ValueError, ['Program Files', 'C:\\Program Files'])
check(['C:\\Program Files'], 'C:\\Program Files')
check(['C:\\Program Files', 'C:\\Program Files'], 'C:\\Program Files')
check(['C:\\Program Files\\', 'C:\\Program Files'],
'C:\\Program Files')
check(['C:\\Program Files\\', 'C:\\Program Files\\'],
'C:\\Program Files')
check(['C:\\\\Program Files', 'C:\\Program Files\\\\'],
'C:\\Program Files')
check(['C:\\.\\Program Files', 'C:\\Program Files\\.'],
'C:\\Program Files')
check(['C:\\', 'C:\\bin'], 'C:\\')
check(['C:\\Program Files', 'C:\\bin'], 'C:\\')
check(['C:\\Program Files', 'C:\\Program Files\\Bar'],
'C:\\Program Files')
check(['C:\\Program Files\\Foo', 'C:\\Program Files\\Bar'],
'C:\\Program Files')
check(['C:\\Program Files', 'C:\\Projects'], 'C:\\')
check(['C:\\Program Files\\', 'C:\\Projects'], 'C:\\')
check(['C:\\Program Files\\Foo', 'C:/Program Files/Bar'],
'C:\\Program Files')
check(['C:\\Program Files\\Foo', 'c:/program files/bar'],
'C:\\Program Files')
check(['c:/program files/bar', 'C:\\Program Files\\Foo'],
'c:\\program files')
check_error(ValueError, ['C:\\Program Files', 'D:\\Program Files'])
check(['spam'], 'spam')
check(['spam', 'spam'], 'spam')
check(['spam', 'alot'], '')
check(['and\\jam', 'and\\spam'], 'and')
check(['and\\\\jam', 'and\\spam\\\\'], 'and')
check(['and\\.\\jam', '.\\and\\spam'], 'and')
check(['and\\jam', 'and\\spam', 'alot'], '')
check(['and\\jam', 'and\\spam', 'and'], 'and')
check(['C:and\\jam', 'C:and\\spam'], 'C:and')
check([''], '')
check(['', 'spam\\alot'], '')
check_error(ValueError, ['', '\\spam\\alot'])
self.assertRaises(TypeError, ntpath.commonpath,
[b'C:\\Program Files', 'C:\\Program Files\\Foo'])
self.assertRaises(TypeError, ntpath.commonpath,
[b'C:\\Program Files', 'Program Files\\Foo'])
self.assertRaises(TypeError, ntpath.commonpath,
[b'Program Files', 'C:\\Program Files\\Foo'])
self.assertRaises(TypeError, ntpath.commonpath,
['C:\\Program Files', b'C:\\Program Files\\Foo'])
self.assertRaises(TypeError, ntpath.commonpath,
['C:\\Program Files', b'Program Files\\Foo'])
self.assertRaises(TypeError, ntpath.commonpath,
['Program Files', b'C:\\Program Files\\Foo'])
def test_sameopenfile(self):
with TemporaryFile() as tf1, TemporaryFile() as tf2:
# Make sure the same file is really the same

54
Lib/test/test_posixpath.py
View File

@ -522,6 +522,60 @@ class PosixPathTest(unittest.TestCase):
finally:
os.getcwdb = real_getcwdb
def test_commonpath(self):
def check(paths, expected):
self.assertEqual(posixpath.commonpath(paths), expected)
self.assertEqual(posixpath.commonpath([os.fsencode(p) for p in paths]),
os.fsencode(expected))
def check_error(exc, paths):
self.assertRaises(exc, posixpath.commonpath, paths)
self.assertRaises(exc, posixpath.commonpath,
[os.fsencode(p) for p in paths])
self.assertRaises(ValueError, posixpath.commonpath, [])
check_error(ValueError, ['/usr', 'usr'])
check_error(ValueError, ['usr', '/usr'])
check(['/usr/local'], '/usr/local')
check(['/usr/local', '/usr/local'], '/usr/local')
check(['/usr/local/', '/usr/local'], '/usr/local')
check(['/usr/local/', '/usr/local/'], '/usr/local')
check(['/usr//local', '//usr/local'], '/usr/local')
check(['/usr/./local', '/./usr/local'], '/usr/local')
check(['/', '/dev'], '/')
check(['/usr', '/dev'], '/')
check(['/usr/lib/', '/usr/lib/python3'], '/usr/lib')
check(['/usr/lib/', '/usr/lib64/'], '/usr')
check(['/usr/lib', '/usr/lib64'], '/usr')
check(['/usr/lib/', '/usr/lib64'], '/usr')
check(['spam'], 'spam')
check(['spam', 'spam'], 'spam')
check(['spam', 'alot'], '')
check(['and/jam', 'and/spam'], 'and')
check(['and//jam', 'and/spam//'], 'and')
check(['and/./jam', './and/spam'], 'and')
check(['and/jam', 'and/spam', 'alot'], '')
check(['and/jam', 'and/spam', 'and'], 'and')
check([''], '')
check(['', 'spam/alot'], '')
check_error(ValueError, ['', '/spam/alot'])
self.assertRaises(TypeError, posixpath.commonpath,
[b'/usr/lib/', '/usr/lib/python3'])
self.assertRaises(TypeError, posixpath.commonpath,
[b'/usr/lib/', 'usr/lib/python3'])
self.assertRaises(TypeError, posixpath.commonpath,
[b'usr/lib/', '/usr/lib/python3'])
self.assertRaises(TypeError, posixpath.commonpath,
['/usr/lib/', b'/usr/lib/python3'])
self.assertRaises(TypeError, posixpath.commonpath,
['/usr/lib/', b'usr/lib/python3'])
self.assertRaises(TypeError, posixpath.commonpath,
['usr/lib/', b'/usr/lib/python3'])
class PosixCommonTest(test_genericpath.CommonTest, unittest.TestCase):
pathmodule = posixpath

3
Misc/NEWS
View File

@ -13,6 +13,9 @@ Core and Builtins
Library
-------
- Issue #10395: Added os.path.commonpath(). Implemented in posixpath and ntpath.
Based on patch by Rafik Draoui.
- Issue #23611: Serializing more "lookupable" objects (such as unbound methods
or nested classes) now are supported with pickle protocols < 4.