upath: implement poc for flavour base vendoring

.pre-commit-config.yaml

@@ -1,6 +1,6 @@
 default_language_version:
   python: python3
-exclude: ^upath/tests/pathlib/test_pathlib.*\.py|^upath/tests/pathlib/_test_support\.py
+exclude: ^upath/tests/pathlib/test_pathlib.*\.py|^upath/tests/pathlib/_test_support\.py|^upath/_flavour_sources\.py
 repos:
   - repo: https://github.com/psf/black
     rev: 24.1.1

README.md

@@ -346,7 +346,7 @@ If you distribute your implementation in your own Python package, you can inform
 
 ```
 # pyproject.toml
-[project.entry-points."unversal_pathlib.implementations"]
+[project.entry-points."universal_pathlib.implementations"]
 myproto = "my_module.submodule:MyPath"
 ```
 

dev/generate_flavours.py

@@ -0,0 +1,350 @@
+"""Generates the _flavour_sources.py file"""
+
+from __future__ import annotations
+
+import inspect
+import re
+import sys
+import warnings
+from io import StringIO
+from typing import Any
+from unittest.mock import Mock
+
+from fsspec.registry import available_protocols
+from fsspec.registry import get_filesystem_class
+from fsspec.spec import AbstractFileSystem
+from fsspec.utils import get_package_version_without_import
+
+HEADER = '''\
+""" upath._flavour_sources
+
+<experimental!>
+
+Warning
+-------
+  Do not modify this file manually!
+  It is generated by `dev/generate_flavours.py`
+
+To be able to parse the different filesystem uri schemes, we need
+the string parsing functionality each of the filesystem implementations.
+In an attempt to support parsing uris without having to import the
+specific filesystems, we extract the necessary subset of the
+AbstractFileSystem classes and generate a new "flavour" class for
+each of the known filesystems. This will allow us to provide a
+`PurePath` equivalent `PureUPath` for each protocol in the future
+without a direct dependency on the underlying filesystem package.
+
+"""
+'''
+
+IMPORTS = """\
+from __future__ import annotations
+
+import logging
+import re
+from typing import Any
+from typing import cast
+from urllib.parse import parse_qs
+from urllib.parse import urlsplit
+
+from fsspec.implementations.local import make_path_posix
+from fsspec.utils import infer_storage_options
+from fsspec.utils import stringify_path
+
+"""
+
+INIT_CODE = '''\
+__all__ = [
+    "AbstractFileSystemFlavour",
+    "FileSystemFlavourBase",
+    "flavour_registry",
+]
+
+logger = logging.getLogger(__name__)
+flavour_registry: dict[str, type[FileSystemFlavourBase]] = {}
+
+
+class FileSystemFlavourBase:
+    """base class for the fsspec flavours"""
+
+    def __init_subclass__(cls: Any, **kwargs):
+        if isinstance(cls.protocol, str):
+            protocols = (cls.protocol,)
+        else:
+            protocols = tuple(cls.protocol)
+        for protocol in protocols:
+            if protocol in flavour_registry:
+                raise ValueError(f"protocol {protocol!r} already registered")
+            flavour_registry[protocol] = cls
+'''
+
+BASE_CLASS_NAME_SUFFIX = "Flavour"
+BASE_CLASS_NAME = f"{AbstractFileSystem.__name__}{BASE_CLASS_NAME_SUFFIX}"
+
+SKIP_PROTOCOLS = [
+    "dir",
+    "blockcache",
+    "cached",
+    "simplecache",
+    "filecache",
+]
+
+FIX_PROTOCOLS = {
+    "MemFS": ("memfs",),
+    "AsyncLocalFileSystem": (),
+}
+
+FIX_METHODS = {
+    "GCSFileSystem": ["_strip_protocol", "_get_kwargs_from_urls", "_split_path"],
+}
+
+
+def _fix_azure_blob_file_system(x: str) -> str:
+    return re.sub(
+        r"host = ops.get\(\"host\", None\)",
+        'host: str | None = ops.get("host", None)',
+        x,
+    )
+
+
+def _fix_memfs_file_system(x: str) -> str:
+    return re.sub(
+        "_MemFS",
+        "MemoryFileSystemFlavour",
+        x,
+    )
+
+
+def _fix_xrootd_file_system(x: str) -> str:
+    x = re.sub(
+        r"client.URL",
+        "urlsplit",
+        x,
+    )
+    return re.sub(
+        "url.hostid",
+        "url.netloc",
+        x,
+    )
+
+
+FIX_SOURCE = {
+    "AzureBlobFileSystem": _fix_azure_blob_file_system,
+    "MemFS": _fix_memfs_file_system,
+    "XRootDFileSystem": _fix_xrootd_file_system,
+}
+
+
+def before_imports() -> None:
+    """allow to patch the generated state before importing anything"""
+    # patch libarchive
+    sys.modules["libarchive"] = Mock()
+    sys.modules["libarchive.ffi"] = Mock()
+    # patch xrootd
+    sys.modules["XRootD"] = Mock()
+    sys.modules["XRootD.client"] = Mock()
+    sys.modules["XRootD.client.flags"] = Mock()
+    sys.modules["XRootD.client.responses"] = Mock()
+
+
+def get_protos(cls: type, remove: str, add: str) -> tuple[str, ...]:
+    try:
+        return FIX_PROTOCOLS[cls.__name__]
+    except KeyError:
+        pass
+    if isinstance(cls.protocol, str):
+        p = [cls.protocol, add]
+    else:
+        p = [*cls.protocol, add]
+    return tuple([x for x in p if x != remove])
+
+
+def get_fsspec_filesystems_and_protocol_errors() -> (
+    tuple[dict[type[AbstractFileSystem], tuple[str, ...]], dict[str, str]]
+):
+    before_imports()
+
+    classes: dict[type[AbstractFileSystem], tuple[str]] = {}
+    errors: dict[str, str] = {}
+
+    for protocol in available_protocols():
+        if protocol in SKIP_PROTOCOLS:
+            continue
+        try:
+            cls = get_filesystem_class(protocol)
+        except ImportError as err:
+            errors[protocol] = str(err)
+        else:
+            protos = get_protos(cls, remove="abstract", add=protocol)
+            cprotos = classes.get(cls, [])
+            classes[cls] = tuple(dict.fromkeys([*cprotos, *protos]))
+    return classes, errors
+
+
+def _get_plain_method(cls, name):
+    for c in cls.__mro__:
+        try:
+            return c.__dict__[name]
+        except KeyError:
+            pass
+    else:
+        raise AttributeError(f"{cls.__name__}.{name} not found")
+
+
+def get_subclass_methods(cls: type) -> list[str]:  # noqa: C901
+    try:
+        return FIX_METHODS[cls.__name__]
+    except KeyError:
+        pass
+    errors = []
+
+    # storage options
+    so = None
+    base_get_kwargs_from_urls = _get_plain_method(
+        AbstractFileSystem, "_get_kwargs_from_urls"
+    )
+    try:
+        cls_get_kwargs_from_urls = _get_plain_method(cls, "_get_kwargs_from_urls")
+    except AttributeError:
+        errors.append("missing `_get_kwargs_from_urls()`")
+    else:
+        so = cls_get_kwargs_from_urls is base_get_kwargs_from_urls
+        if not isinstance(cls_get_kwargs_from_urls, staticmethod):
+            warnings.warn(
+                f"{cls.__name__}: {cls_get_kwargs_from_urls!r} not a staticmethod",
+                RuntimeWarning,
+                stacklevel=2,
+            )
+
+    # strip protocol
+    sp = None
+    base_strip_protocol = _get_plain_method(AbstractFileSystem, "_strip_protocol")
+    try:
+        cls_strip_protocol = _get_plain_method(cls, "_strip_protocol")
+    except AttributeError:
+        errors.append("missing `_strip_protocol()`")
+    else:
+        if isinstance(cls_strip_protocol, staticmethod):
+            warnings.warn(
+                f"{cls.__name__}: {cls_strip_protocol.__name__!r} is not a classmethod",
+                UserWarning,
+                stacklevel=2,
+            )
+            sp = False
+        elif isinstance(cls_strip_protocol, classmethod):
+            sp = cls_strip_protocol.__func__ is base_strip_protocol.__func__
+        else:
+            errors.append(
+                f"{cls.__name__}: {cls_strip_protocol.__name__!r} not a classmethod"
+            )
+
+    # _parent
+    pt = None
+    base_parent = _get_plain_method(AbstractFileSystem, "_parent")
+    try:
+        cls_parent = _get_plain_method(cls, "_parent")
+    except AttributeError:
+        errors.append("missing `_parent()`")
+    else:
+        pt = cls_parent is base_parent
+
+    if errors or sp is None or so is None:
+        raise AttributeError(" AND ".join(errors))
+
+    methods = []
+    if not sp:
+        methods.append("_strip_protocol")
+    if not so:
+        methods.append("_get_kwargs_from_urls")
+    if not pt:
+        methods.append("_parent")
+    return methods
+
+
+def generate_class_source_code(
+    cls: type,
+    methods: list[str],
+    overrides: dict[str, Any],
+    attributes: list[str],
+    cls_suffix: str,
+    base_cls: str | None,
+) -> str:
+    s = ["\n"]
+    if base_cls:
+        s += [f"class {cls.__name__}{cls_suffix}({base_cls}):"]
+    else:
+        s += [f"class {cls.__name__}{cls_suffix}:"]
+    mod_ver = get_package_version_without_import(cls.__module__.partition(".")[0])
+    s.append(f"    __orig_class__ = '{cls.__module__}.{cls.__name__}'")
+    s.append(f"    __orig_version__ = {mod_ver!r}")
+    for attr, value in overrides.items():
+        s.append(f"    {attr} = {value!r}")
+    for attr in attributes:
+        s.append(f"    {attr} = {getattr(cls, attr)!r}")
+    s.append("")
+    for method in methods:
+        s.append(inspect.getsource(getattr(cls, method)))
+    try:
+        fix_func = FIX_SOURCE[cls.__name__]
+    except KeyError:
+        return "\n".join(s)
+    else:
+        return "\n".join(fix_func(line) for line in s)
+
+
+def create_source() -> str:
+    buf = StringIO()
+    buf.write(HEADER)
+
+    classes, errors = get_fsspec_filesystems_and_protocol_errors()
+
+    srcs = [
+        generate_class_source_code(
+            AbstractFileSystem,
+            ["_strip_protocol", "_get_kwargs_from_urls", "_parent"],
+            {},
+            ["protocol", "root_marker"],
+            cls_suffix=BASE_CLASS_NAME_SUFFIX,
+            base_cls="FileSystemFlavourBase",
+        )
+    ]
+
+    for cls in sorted(classes, key=lambda cls: cls.__name__):
+        try:
+            sub_cls_methods = get_subclass_methods(cls)
+        except AttributeError as err:
+            protos = (cls.protocol,) if isinstance(cls.protocol, str) else cls.protocol
+            for proto in protos:
+                errors[proto] = str(err)
+            continue
+        sub_cls = generate_class_source_code(
+            cls,
+            sub_cls_methods,
+            {"protocol": classes[cls]},
+            ["root_marker", "sep"],
+            cls_suffix=BASE_CLASS_NAME_SUFFIX,
+            base_cls=BASE_CLASS_NAME,
+        )
+        srcs.append(sub_cls)
+
+    if SKIP_PROTOCOLS:
+        buf.write("#\n# skipping protocols:\n")
+        for protocol in sorted(SKIP_PROTOCOLS):
+            buf.write(f"#   - {protocol}\n")
+
+    if errors:
+        buf.write("# protocol import errors:\n")
+        for protocol, error_msg in sorted(errors.items()):
+            buf.write(f"#   - {protocol} ({error_msg})\n")
+        buf.write("#\n")
+
+    buf.write(IMPORTS)
+    buf.write(INIT_CODE)
+    for cls_src in srcs:
+        buf.write(cls_src)
+
+    return buf.getvalue().removesuffix("\n")
+
+
+if __name__ == "__main__":
+    print(create_source())