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[WIP/RFC] pathlib: revisit error handling #23025

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[WIP/RFC] pathlib: revisit error handling #23025

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2883096
pathlib: _Selector: factor out _skip_entry
blueyed Oct 29, 2020
ff099bc
use "yield from"
blueyed Oct 29, 2020
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91 changes: 43 additions & 48 deletions Lib/pathlib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -502,6 +502,21 @@ def __init__(self, child_parts, flavour):
self.successor = _TerminatingSelector()
self.dironly = False

def _skip_entry(self, entry):
if self.dironly:
try:
return not entry.is_dir()
except PermissionError:
# "entry.is_dir()" can raise PermissionError
# in some cases (see bpo-38894), which is not
# among the errors ignored by _ignore_error().
return True
except OSError as e:
if not _ignore_error(e):
raise
return True
return False

def select_from(self, parent_path):
"""Iterate over all child paths of `parent_path` matched by this
selector. This can contain parent_path itself."""
Expand All @@ -527,13 +542,13 @@ def __init__(self, name, child_parts, flavour):
_Selector.__init__(self, child_parts, flavour)

def _select_from(self, parent_path, is_dir, exists, scandir):
path = parent_path._make_child_relpath(self.name)
try:
path = parent_path._make_child_relpath(self.name)
if (is_dir if self.dironly else exists)(path):
for p in self.successor._select_from(path, is_dir, exists, scandir):
yield p
if not (is_dir if self.dironly else exists)(path):
return
except PermissionError:
return
yield from self.successor._select_from(path, is_dir, exists, scandir)


class _WildcardSelector(_Selector):
Expand All @@ -546,25 +561,15 @@ def _select_from(self, parent_path, is_dir, exists, scandir):
try:
with scandir(parent_path) as scandir_it:
entries = list(scandir_it)
for entry in entries:
if self.dironly:
try:
# "entry.is_dir()" can raise PermissionError
# in some cases (see bpo-38894), which is not
# among the errors ignored by _ignore_error()
if not entry.is_dir():
continue
except OSError as e:
if not _ignore_error(e):
raise
continue
name = entry.name
if self.match(name):
path = parent_path._make_child_relpath(name)
for p in self.successor._select_from(path, is_dir, exists, scandir):
yield p
except PermissionError:
return
for entry in entries:
if self._skip_entry(entry):
continue
name = entry.name
if self.match(name):
path = parent_path._make_child_relpath(name)
yield from self.successor._select_from(path, is_dir, exists, scandir)


class _RecursiveWildcardSelector(_Selector):
Expand All @@ -577,34 +582,26 @@ def _iterate_directories(self, parent_path, is_dir, scandir):
try:
with scandir(parent_path) as scandir_it:
entries = list(scandir_it)
for entry in entries:
entry_is_dir = False
try:
entry_is_dir = entry.is_dir()
except OSError as e:
if not _ignore_error(e):
raise
if entry_is_dir and not entry.is_symlink():
path = parent_path._make_child_relpath(entry.name)
for p in self._iterate_directories(path, is_dir, scandir):
yield p
except PermissionError:
return
for entry in entries:
if self._skip_entry(entry):
continue
if not entry.is_symlink():
path = parent_path._make_child_relpath(entry.name)
yield from self._iterate_directories(path, is_dir, scandir)

def _select_from(self, parent_path, is_dir, exists, scandir):
yielded = set()
try:
yielded = set()
try:
successor_select = self.successor._select_from
for starting_point in self._iterate_directories(parent_path, is_dir, scandir):
for p in successor_select(starting_point, is_dir, exists, scandir):
if p not in yielded:
yield p
yielded.add(p)
finally:
yielded.clear()
except PermissionError:
return
successor_select = self.successor._select_from
for starting_point in self._iterate_directories(parent_path, is_dir, scandir):
for p in successor_select(starting_point, is_dir, exists, scandir):
if p not in yielded:
yield p
yielded.add(p)
finally:
yielded.clear()


#
Expand Down Expand Up @@ -1163,8 +1160,7 @@ def glob(self, pattern):
if drv or root:
raise NotImplementedError("Non-relative patterns are unsupported")
selector = _make_selector(tuple(pattern_parts), self._flavour)
for p in selector.select_from(self):
yield p
yield from selector.select_from(self)

def rglob(self, pattern):
"""Recursively yield all existing files (of any kind, including
Expand All @@ -1176,8 +1172,7 @@ def rglob(self, pattern):
if drv or root:
raise NotImplementedError("Non-relative patterns are unsupported")
selector = _make_selector(("**",) + tuple(pattern_parts), self._flavour)
for p in selector.select_from(self):
yield p
yield from selector.select_from(self)

def absolute(self):
"""Return an absolute version of this path. This function works
Expand Down