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jaracojaraco
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bpo-42129: Add support for resources in namespaces (GH-24670)
* Unify behavior in ResourceReaderDefaultsTests and align with the behavior found in importlib_resources. * Equip NamespaceLoader with a NamespaceReader. * Apply changes from importlib_resources 5.0.4
1 parent fbf75b9 commit 6714825

21 files changed

Lines changed: 1319 additions & 920 deletions

‎Lib/importlib/_adapters.py‎

Lines changed: 82 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,82 @@
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from contextlib import suppress
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from . import abc
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class SpecLoaderAdapter:
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"""
8+
Adapt a package spec to adapt the underlying loader.
9+
"""
10+
11+
def __init__(self, spec, adapter=lambda spec: spec.loader):
12+
self.spec = spec
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self.loader = adapter(spec)
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def __getattr__(self, name):
16+
return getattr(self.spec, name)
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class TraversableResourcesLoader:
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"""
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Adapt a loader to provide TraversableResources.
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"""
23+
24+
def __init__(self, spec):
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self.spec = spec
26+
27+
def get_resource_reader(self, name):
28+
return DegenerateFiles(self.spec)._native()
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30+
31+
class DegenerateFiles:
32+
"""
33+
Adapter for an existing or non-existant resource reader
34+
to provide a degenerate .files().
35+
"""
36+
37+
class Path(abc.Traversable):
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def iterdir(self):
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return iter(())
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41+
def is_dir(self):
42+
return False
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is_file = exists = is_dir # type: ignore
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46+
def joinpath(self, other):
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return DegenerateFiles.Path()
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49+
def name(self):
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return ''
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52+
def open(self):
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raise ValueError()
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55+
def __init__(self, spec):
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self.spec = spec
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58+
@property
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def _reader(self):
60+
with suppress(AttributeError):
61+
return self.spec.loader.get_resource_reader(self.spec.name)
62+
63+
def _native(self):
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"""
65+
Return the native reader if it supports files().
66+
"""
67+
reader = self._reader
68+
return reader if hasattr(reader, 'files') else self
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70+
def __getattr__(self, attr):
71+
return getattr(self._reader, attr)
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def files(self):
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return DegenerateFiles.Path()
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def wrap_spec(package):
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"""
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Construct a package spec with traversable compatibility
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on the spec/loader/reader.
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"""
82+
return SpecLoaderAdapter(package.__spec__, TraversableResourcesLoader)

‎Lib/importlib/_bootstrap_external.py‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1259,6 +1259,10 @@ def load_module(self, fullname):
12591259
# Warning implemented in _load_module_shim().
12601260
return _bootstrap._load_module_shim(self, fullname)
12611261

1262+
def get_resource_reader(self, module):
1263+
from importlib.readers import NamespaceReader
1264+
return NamespaceReader(self._path)
1265+
12621266

12631267
# Finders #####################################################################
12641268

‎Lib/importlib/_common.py‎

Lines changed: 7 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,8 @@
99
from typing import Union, Any, Optional
1010
from .abc import ResourceReader
1111

12+
from ._adapters import wrap_spec
13+
1214
Package = Union[types.ModuleType, str]
1315

1416

@@ -43,18 +45,15 @@ def get_resource_reader(package):
4345
# zipimport.zipimporter does not support weak references, resulting in a
4446
# TypeError. That seems terrible.
4547
spec = package.__spec__
46-
reader = getattr(spec.loader, 'get_resource_reader', None)
48+
reader = getattr(spec.loader, 'get_resource_reader', None) # type: ignore
4749
if reader is None:
4850
return None
49-
return reader(spec.name)
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return reader(spec.name) # type: ignore
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5153

5254
def resolve(cand):
5355
# type: (Package) -> types.ModuleType
54-
return (
55-
cand if isinstance(cand, types.ModuleType)
56-
else importlib.import_module(cand)
57-
)
56+
return cand if isinstance(cand, types.ModuleType) else importlib.import_module(cand)
5857

5958

6059
def get_package(package):
@@ -64,7 +63,7 @@ def get_package(package):
6463
Raise an exception if the resolved module is not a package.
6564
"""
6665
resolved = resolve(package)
67-
if resolved.__spec__.submodule_search_locations is None:
66+
if wrap_spec(resolved).submodule_search_locations is None:
6867
raise TypeError('{!r} is not a package'.format(package))
6968
return resolved
7069

@@ -74,7 +73,7 @@ def from_package(package):
7473
Return a Traversable object for the given package.
7574
7675
"""
77-
spec = package.__spec__
76+
spec = wrap_spec(package)
7877
reader = spec.loader.get_resource_reader(spec.name)
7978
return reader.files()
8079

‎Lib/importlib/abc.py‎

Lines changed: 34 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -14,6 +14,7 @@
1414
from ._abc import Loader
1515
import abc
1616
import warnings
17+
from typing import BinaryIO, Iterable, Text
1718
from typing import Protocol, runtime_checkable
1819

1920

@@ -297,49 +298,45 @@ def set_data(self, path, data):
297298

298299

299300
class ResourceReader(metaclass=abc.ABCMeta):
300-
301-
"""Abstract base class to provide resource-reading support.
302-
303-
Loaders that support resource reading are expected to implement
304-
the ``get_resource_reader(fullname)`` method and have it either return None
305-
or an object compatible with this ABC.
306-
"""
301+
"""Abstract base class for loaders to provide resource reading support."""
307302

308303
@abc.abstractmethod
309-
def open_resource(self, resource):
304+
def open_resource(self, resource: Text) -> BinaryIO:
310305
"""Return an opened, file-like object for binary reading.
311306
312-
The 'resource' argument is expected to represent only a file name
313-
and thus not contain any subdirectory components.
314-
307+
The 'resource' argument is expected to represent only a file name.
315308
If the resource cannot be found, FileNotFoundError is raised.
316309
"""
310+
# This deliberately raises FileNotFoundError instead of
311+
# NotImplementedError so that if this method is accidentally called,
312+
# it'll still do the right thing.
317313
raise FileNotFoundError
318314

319315
@abc.abstractmethod
320-
def resource_path(self, resource):
316+
def resource_path(self, resource: Text) -> Text:
321317
"""Return the file system path to the specified resource.
322318
323-
The 'resource' argument is expected to represent only a file name
324-
and thus not contain any subdirectory components.
325-
319+
The 'resource' argument is expected to represent only a file name.
326320
If the resource does not exist on the file system, raise
327321
FileNotFoundError.
328322
"""
323+
# This deliberately raises FileNotFoundError instead of
324+
# NotImplementedError so that if this method is accidentally called,
325+
# it'll still do the right thing.
329326
raise FileNotFoundError
330327

331328
@abc.abstractmethod
332-
def is_resource(self, name):
333-
"""Return True if the named 'name' is consider a resource."""
329+
def is_resource(self, path: Text) -> bool:
330+
"""Return True if the named 'path' is a resource.
331+
332+
Files are resources, directories are not.
333+
"""
334334
raise FileNotFoundError
335335

336336
@abc.abstractmethod
337-
def contents(self):
338-
"""Return an iterable of strings over the contents of the package."""
339-
return []
340-
341-
342-
_register(ResourceReader, machinery.SourceFileLoader)
337+
def contents(self) -> Iterable[str]:
338+
"""Return an iterable of entries in `package`."""
339+
raise FileNotFoundError
343340

344341

345342
@runtime_checkable
@@ -355,26 +352,28 @@ def iterdir(self):
355352
Yield Traversable objects in self
356353
"""
357354

358-
@abc.abstractmethod
359355
def read_bytes(self):
360356
"""
361357
Read contents of self as bytes
362358
"""
359+
with self.open('rb') as strm:
360+
return strm.read()
363361

364-
@abc.abstractmethod
365362
def read_text(self, encoding=None):
366363
"""
367-
Read contents of self as bytes
364+
Read contents of self as text
368365
"""
366+
with self.open(encoding=encoding) as strm:
367+
return strm.read()
369368

370369
@abc.abstractmethod
371-
def is_dir(self):
370+
def is_dir(self) -> bool:
372371
"""
373372
Return True if self is a dir
374373
"""
375374

376375
@abc.abstractmethod
377-
def is_file(self):
376+
def is_file(self) -> bool:
378377
"""
379378
Return True if self is a file
380379
"""
@@ -385,11 +384,11 @@ def joinpath(self, child):
385384
Return Traversable child in self
386385
"""
387386

388-
@abc.abstractmethod
389387
def __truediv__(self, child):
390388
"""
391389
Return Traversable child in self
392390
"""
391+
return self.joinpath(child)
393392

394393
@abc.abstractmethod
395394
def open(self, mode='r', *args, **kwargs):
@@ -402,14 +401,18 @@ def open(self, mode='r', *args, **kwargs):
402401
"""
403402

404403
@abc.abstractproperty
405-
def name(self):
406-
# type: () -> str
404+
def name(self) -> str:
407405
"""
408406
The base name of this object without any parent references.
409407
"""
410408

411409

412410
class TraversableResources(ResourceReader):
411+
"""
412+
The required interface for providing traversable
413+
resources.
414+
"""
415+
413416
@abc.abstractmethod
414417
def files(self):
415418
"""Return a Traversable object for the loaded package."""

‎Lib/importlib/readers.py‎

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Original file line numberDiff line numberDiff line change
@@ -1,8 +1,13 @@
1+
import collections
12
import zipfile
23
import pathlib
34
from . import abc
45

56

7+
def remove_duplicates(items):
8+
return iter(collections.OrderedDict.fromkeys(items))
9+
10+
611
class FileReader(abc.TraversableResources):
712
def __init__(self, loader):
813
self.path = pathlib.Path(loader.path).parent
@@ -39,3 +44,80 @@ def is_resource(self, path):
3944

4045
def files(self):
4146
return zipfile.Path(self.archive, self.prefix)
47+
48+
49+
class MultiplexedPath(abc.Traversable):
50+
"""
51+
Given a series of Traversable objects, implement a merged
52+
version of the interface across all objects. Useful for
53+
namespace packages which may be multihomed at a single
54+
name.
55+
"""
56+
57+
def __init__(self, *paths):
58+
self._paths = list(map(pathlib.Path, remove_duplicates(paths)))
59+
if not self._paths:
60+
message = 'MultiplexedPath must contain at least one path'
61+
raise FileNotFoundError(message)
62+
if not all(path.is_dir() for path in self._paths):
63+
raise NotADirectoryError('MultiplexedPath only supports directories')
64+
65+
def iterdir(self):
66+
visited = []
67+
for path in self._paths:
68+
for file in path.iterdir():
69+
if file.name in visited:
70+
continue
71+
visited.append(file.name)
72+
yield file
73+
74+
def read_bytes(self):
75+
raise FileNotFoundError(f'{self} is not a file')
76+
77+
def read_text(self, *args, **kwargs):
78+
raise FileNotFoundError(f'{self} is not a file')
79+
80+
def is_dir(self):
81+
return True
82+
83+
def is_file(self):
84+
return False
85+
86+
def joinpath(self, child):
87+
# first try to find child in current paths
88+
for file in self.iterdir():
89+
if file.name == child:
90+
return file
91+
# if it does not exist, construct it with the first path
92+
return self._paths[0] / child
93+
94+
__truediv__ = joinpath
95+
96+
def open(self, *args, **kwargs):
97+
raise FileNotFoundError('{} is not a file'.format(self))
98+
99+
def name(self):
100+
return self._paths[0].name
101+
102+
def __repr__(self):
103+
return 'MultiplexedPath({})'.format(
104+
', '.join("'{}'".format(path) for path in self._paths)
105+
)
106+
107+
108+
class NamespaceReader(abc.TraversableResources):
109+
def __init__(self, namespace_path):
110+
if 'NamespacePath' not in str(namespace_path):
111+
raise ValueError('Invalid path')
112+
self.path = MultiplexedPath(*list(namespace_path))
113+
114+
def resource_path(self, resource):
115+
"""
116+
Return the file system path to prevent
117+
`resources.path()` from creating a temporary
118+
copy.
119+
"""
120+
return str(self.path.joinpath(resource))
121+
122+
def files(self):
123+
return self.path

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