refactor(pypi): split out code for env marker evaluation for reuse (#2068)

This is just a small PR to reduce the scope of #2059.

This just moves some code from one python file to a separate one.

Work towards #260, #1105, #1868.

Author: aignas

python/private/pypi/whl_installer/BUILD.bazel

@@ -5,6 +5,7 @@ py_library(
     srcs = [
         "arguments.py",
         "namespace_pkgs.py",
+        "platform.py",
         "wheel.py",
         "wheel_installer.py",
     ],

python/private/pypi/whl_installer/arguments.py

@@ -17,7 +17,7 @@
 import pathlib
 from typing import Any, Dict, Set
 
-from python.private.pypi.whl_installer import wheel
+from python.private.pypi.whl_installer.platform import Platform
 
 
 def parser(**kwargs: Any) -> argparse.ArgumentParser:
@@ -44,7 +44,7 @@ def parser(**kwargs: Any) -> argparse.ArgumentParser:
     parser.add_argument(
         "--platform",
         action="extend",
-        type=wheel.Platform.from_string,
+        type=Platform.from_string,
         help="Platforms to target dependencies. Can be used multiple times.",
     )
     parser.add_argument(

python/private/pypi/whl_installer/platform.py

@@ -0,0 +1,302 @@
+# Copyright 2024 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Utility class to inspect an extracted wheel directory"""
+
+import platform
+import sys
+from dataclasses import dataclass
+from enum import Enum
+from typing import Any, Dict, Iterator, List, Optional, Union
+
+
+class OS(Enum):
+    linux = 1
+    osx = 2
+    windows = 3
+    darwin = osx
+    win32 = windows
+
+    @classmethod
+    def interpreter(cls) -> "OS":
+        "Return the interpreter operating system."
+        return cls[sys.platform.lower()]
+
+    def __str__(self) -> str:
+        return self.name.lower()
+
+
+class Arch(Enum):
+    x86_64 = 1
+    x86_32 = 2
+    aarch64 = 3
+    ppc = 4
+    s390x = 5
+    arm = 6
+    amd64 = x86_64
+    arm64 = aarch64
+    i386 = x86_32
+    i686 = x86_32
+    x86 = x86_32
+    ppc64le = ppc
+
+    @classmethod
+    def interpreter(cls) -> "Arch":
+        "Return the currently running interpreter architecture."
+        # FIXME @aignas 2023-12-13: Hermetic toolchain on Windows 3.11.6
+        # is returning an empty string here, so lets default to x86_64
+        return cls[platform.machine().lower() or "x86_64"]
+
+    def __str__(self) -> str:
+        return self.name.lower()
+
+
+def _as_int(value: Optional[Union[OS, Arch]]) -> int:
+    """Convert one of the enums above to an int for easier sorting algorithms.
+
+    Args:
+        value: The value of an enum or None.
+
+    Returns:
+        -1 if we get None, otherwise, the numeric value of the given enum.
+    """
+    if value is None:
+        return -1
+
+    return int(value.value)
+
+
+def host_interpreter_minor_version() -> int:
+    return sys.version_info.minor
+
+
+@dataclass(frozen=True)
+class Platform:
+    os: Optional[OS] = None
+    arch: Optional[Arch] = None
+    minor_version: Optional[int] = None
+
+    @classmethod
+    def all(
+        cls,
+        want_os: Optional[OS] = None,
+        minor_version: Optional[int] = None,
+    ) -> List["Platform"]:
+        return sorted(
+            [
+                cls(os=os, arch=arch, minor_version=minor_version)
+                for os in OS
+                for arch in Arch
+                if not want_os or want_os == os
+            ]
+        )
+
+    @classmethod
+    def host(cls) -> List["Platform"]:
+        """Use the Python interpreter to detect the platform.
+
+        We extract `os` from sys.platform and `arch` from platform.machine
+
+        Returns:
+            A list of parsed values which makes the signature the same as
+            `Platform.all` and `Platform.from_string`.
+        """
+        return [
+            Platform(
+                os=OS.interpreter(),
+                arch=Arch.interpreter(),
+                minor_version=host_interpreter_minor_version(),
+            )
+        ]
+
+    def all_specializations(self) -> Iterator["Platform"]:
+        """Return the platform itself and all its unambiguous specializations.
+
+        For more info about specializations see
+        https://bazel.build/docs/configurable-attributes
+        """
+        yield self
+        if self.arch is None:
+            for arch in Arch:
+                yield Platform(os=self.os, arch=arch, minor_version=self.minor_version)
+        if self.os is None:
+            for os in OS:
+                yield Platform(os=os, arch=self.arch, minor_version=self.minor_version)
+        if self.arch is None and self.os is None:
+            for os in OS:
+                for arch in Arch:
+                    yield Platform(os=os, arch=arch, minor_version=self.minor_version)
+
+    def __lt__(self, other: Any) -> bool:
+        """Add a comparison method, so that `sorted` returns the most specialized platforms first."""
+        if not isinstance(other, Platform) or other is None:
+            raise ValueError(f"cannot compare {other} with Platform")
+
+        self_arch, self_os = _as_int(self.arch), _as_int(self.os)
+        other_arch, other_os = _as_int(other.arch), _as_int(other.os)
+
+        if self_os == other_os:
+            return self_arch < other_arch
+        else:
+            return self_os < other_os
+
+    def __str__(self) -> str:
+        if self.minor_version is None:
+            if self.os is None and self.arch is None:
+                return "//conditions:default"
+
+            if self.arch is None:
+                return f"@platforms//os:{self.os}"
+            else:
+                return f"{self.os}_{self.arch}"
+
+        if self.arch is None and self.os is None:
+            return f"@//python/config_settings:is_python_3.{self.minor_version}"
+
+        if self.arch is None:
+            return f"cp3{self.minor_version}_{self.os}_anyarch"
+
+        if self.os is None:
+            return f"cp3{self.minor_version}_anyos_{self.arch}"
+
+        return f"cp3{self.minor_version}_{self.os}_{self.arch}"
+
+    @classmethod
+    def from_string(cls, platform: Union[str, List[str]]) -> List["Platform"]:
+        """Parse a string and return a list of platforms"""
+        platform = [platform] if isinstance(platform, str) else list(platform)
+        ret = set()
+        for p in platform:
+            if p == "host":
+                ret.update(cls.host())
+                continue
+
+            abi, _, tail = p.partition("_")
+            if not abi.startswith("cp"):
+                # The first item is not an abi
+                tail = p
+                abi = ""
+            os, _, arch = tail.partition("_")
+            arch = arch or "*"
+
+            minor_version = int(abi[len("cp3") :]) if abi else None
+
+            if arch != "*":
+                ret.add(
+                    cls(
+                        os=OS[os] if os != "*" else None,
+                        arch=Arch[arch],
+                        minor_version=minor_version,
+                    )
+                )
+
+            else:
+                ret.update(
+                    cls.all(
+                        want_os=OS[os] if os != "*" else None,
+                        minor_version=minor_version,
+                    )
+                )
+
+        return sorted(ret)
+
+    # NOTE @aignas 2023-12-05: below is the minimum number of accessors that are defined in
+    # https://peps.python.org/pep-0496/ to make rules_python generate dependencies.
+    #
+    # WARNING: It may not work in cases where the python implementation is different between
+    # different platforms.
+
+    # derived from OS
+    @property
+    def os_name(self) -> str:
+        if self.os == OS.linux or self.os == OS.osx:
+            return "posix"
+        elif self.os == OS.windows:
+            return "nt"
+        else:
+            return ""
+
+    @property
+    def sys_platform(self) -> str:
+        if self.os == OS.linux:
+            return "linux"
+        elif self.os == OS.osx:
+            return "darwin"
+        elif self.os == OS.windows:
+            return "win32"
+        else:
+            return ""
+
+    @property
+    def platform_system(self) -> str:
+        if self.os == OS.linux:
+            return "Linux"
+        elif self.os == OS.osx:
+            return "Darwin"
+        elif self.os == OS.windows:
+            return "Windows"
+        else:
+            return ""
+
+    # derived from OS and Arch
+    @property
+    def platform_machine(self) -> str:
+        """Guess the target 'platform_machine' marker.
+
+        NOTE @aignas 2023-12-05: this may not work on really new systems, like
+        Windows if they define the platform markers in a different way.
+        """
+        if self.arch == Arch.x86_64:
+            return "x86_64"
+        elif self.arch == Arch.x86_32 and self.os != OS.osx:
+            return "i386"
+        elif self.arch == Arch.x86_32:
+            return ""
+        elif self.arch == Arch.aarch64 and self.os == OS.linux:
+            return "aarch64"
+        elif self.arch == Arch.aarch64:
+            # Assuming that OSX and Windows use this one since the precedent is set here:
+            # https://github.com/cgohlke/win_arm64-wheels
+            return "arm64"
+        elif self.os != OS.linux:
+            return ""
+        elif self.arch == Arch.ppc64le:
+            return "ppc64le"
+        elif self.arch == Arch.s390x:
+            return "s390x"
+        else:
+            return ""
+
+    def env_markers(self, extra: str) -> Dict[str, str]:
+        # If it is None, use the host version
+        minor_version = self.minor_version or host_interpreter_minor_version()
+
+        return {
+            "extra": extra,
+            "os_name": self.os_name,
+            "sys_platform": self.sys_platform,
+            "platform_machine": self.platform_machine,
+            "platform_system": self.platform_system,
+            "platform_release": "",  # unset
+            "platform_version": "",  # unset
+            "python_version": f"3.{minor_version}",
+            # FIXME @aignas 2024-01-14: is putting zero last a good idea? Maybe we should
+            # use `20` or something else to avoid having weird issues where the full version is used for
+            # matching and the author decides to only support 3.y.5 upwards.
+            "implementation_version": f"3.{minor_version}.0",
+            "python_full_version": f"3.{minor_version}.0",
+            # we assume that the following are the same as the interpreter used to setup the deps:
+            # "implementation_name": "cpython"
+            # "platform_python_implementation: "CPython",
+        }