setup.py

"""
Optional CPython extension for wcwidth.

This setup.py file is required to allow continuing a build even when the extension cannot be
compiled (no compiler, PyPy, Pyodite, who knows), and the pure-python implementation is used.

WCWIDTH_NO_EXTENSION=1 builds the extension-free wheel.  CIBUILDWHEEL=1, which cibuildwheel
sets, makes a compiled extension mandatory.
"""
from __future__ import annotations

import os
import platform
import re
import sys
import sysconfig

import setuptools
from setuptools import Extension, find_packages, setup
from setuptools.command.build_ext import build_ext as _build_ext

try:
    from setuptools.errors import CCompilerError, CompileError, LinkError
except ImportError:
    # compatibility for setuptools < 59
    from distutils.errors import (  # pylint: disable=deprecated-module
        CCompilerError,
        CompileError,
        LinkError,
    )
from distutils.errors import (  # pylint: disable=deprecated-module
    DistutilsExecError,
    DistutilsPlatformError,
)

_PEP621_SETUPTOOLS = (61, 0)
_setuptools_version = tuple(int(part) for part in
                            re.findall(r'\d+', setuptools.__version__)[:2])


def _version_from_source() -> str:
    """Read __version__ from wcwidth/__init__.py."""
    init = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'wcwidth', '__init__.py')
    with open(init, encoding='utf-8') as fp:
        match = re.search(r"^__version__ = '([^']+)'", fp.read(), re.M)
    if match is None:
        raise SystemExit('cannot determine version from wcwidth/__init__.py')
    return match.group(1)


# setuptools<61 ignores [project] and would build package "UNKNOWN 0.0.0";
if _setuptools_version < _PEP621_SETUPTOOLS:
    _FALLBACK_METADATA = {
        'name': 'wcwidth',
        'version': _version_from_source(),
        'packages': find_packages(include=['wcwidth', 'wcwidth.*']),
        'package_data': {'wcwidth': ['py.typed', '*.pyi']},
        'python_requires': '>=3.9',
    }
else:
    _FALLBACK_METADATA = {}

# C11 needs an explicit standard flag on both MSVC and POSIX compilers.
if sys.platform == "win32":
    _C_STANDARD_FLAG = "/std:c11"
else:
    _C_STANDARD_FLAG = "-std=c11"

_EXT_SOURCES = [
    "wcwidth/_wcwidth_c.c",
    # Keep all files below in parity with LIBWCWIDTH_SOURCES in libwcwidth/CMakeLists.txt.
    "libwcwidth/src/bisearch.c",
    "libwcwidth/src/wcwidth.c",
    "libwcwidth/src/wcswidth.c",
    "libwcwidth/src/wcstwidth.c",
    "libwcwidth/src/width.c",
    "libwcwidth/src/textwrap.c",
    "libwcwidth/src/clip.c",
    "libwcwidth/src/align.c",
    "libwcwidth/src/grapheme.c",
    "libwcwidth/src/escape.c",
    "libwcwidth/src/sgr.c",
    "libwcwidth/src/text_sizing.c",
    "libwcwidth/src/terminal_override.c",
    "libwcwidth/src/utf8.c",
    "libwcwidth/src/wcwidth_assert.c",
    "libwcwidth/src/linebreak.c",
    "libwcwidth/src/tables/table_wide.c",
    "libwcwidth/src/tables/table_zero.c",
    "libwcwidth/src/tables/table_ambiguous.c",
    "libwcwidth/src/tables/table_grapheme.c",
    "libwcwidth/src/tables/table_linebreak.c",
    "libwcwidth/src/tables/table_mc.c",
    "libwcwidth/src/tables/table_vs15.c",
    "libwcwidth/src/tables/table_vs16.c",
    "libwcwidth/src/tables/table_terminal_overrides.c",
    "libwcwidth/src/tables/table_term_programs.c",
    "libwcwidth/src/tables/table_gcb_class.c",
    "libwcwidth/src/tables/bitset_tables.c",
]

# Stable ABI (abi3): one cp310 wheel covers every GIL-enabled interpreter from
# 3.10 up.  A 3.9 interpreter installs the pure Python py3-none-any wheel.
PY_LIMITED_API = "0x030A0000"
ABI3_TAG = "cp310"

# Only a 3.10 or newer build can compile against that API.  A free-threaded
# build also cannot use the stable ABI: Py_LIMITED_API below 3.13 drops the
# Py_mod_gil declaration it requires.
USE_LIMITED_API = (not sysconfig.get_config_var("Py_GIL_DISABLED")
                   and sys.version_info >= (3, 10))

# Asserts are conditionally enabled in CI, not for release/wheels
_ASSERT_MACROS = ([("WCWIDTH_ENABLE_ASSERTS", "1")]
                  if os.environ.get("WCWIDTH_ENABLE_ASSERTS") else [])

# setuptools reads purity from ext_modules, and bdist_wheel tags a pure wheel py3-none-any.
if os.environ.get("WCWIDTH_NO_EXTENSION", ""):
    _EXT_MODULES: list[Extension] = []
else:
    _EXT_MODULES = [
        Extension(
            "wcwidth._wcwidth_c",
            sources=_EXT_SOURCES,
            include_dirs=["libwcwidth/include"],
            define_macros=([("Py_LIMITED_API", PY_LIMITED_API)] if USE_LIMITED_API else [])
            + _ASSERT_MACROS,
            py_limited_api=USE_LIMITED_API,
        ),
    ]

# The abi3 tag applies when an extension is built; a 3.9 build stays version specific.
WHEEL_OPTIONS = ({"bdist_wheel": {"py_limited_api": ABI3_TAG}}
                 if _EXT_MODULES and USE_LIMITED_API else {})

# A failed compile would still publish an abi3 wheel with nothing in it: WHEEL_OPTIONS claims
# that tag from _EXT_MODULES alone.
_RELEASE_BUILD = bool(os.environ.get("CIBUILDWHEEL"))

if _RELEASE_BUILD and os.environ.get("WCWIDTH_ENABLE_ASSERTS"):
    raise SystemExit("WCWIDTH_ENABLE_ASSERTS is not permitted for release wheels")


class optional_build_ext(_build_ext):
    """build_ext that warns and continues when the C extension will not build."""

    def finalize_options(self) -> None:
        super().finalize_options()
        for ext in self.extensions:
            ext.extra_compile_args = (ext.extra_compile_args or []) + [_C_STANDARD_FLAG]

    def run(self) -> None:
        if not self.extensions:
            return
        if platform.python_implementation() != "CPython":
            self.fall_back_to_python(f"it cannot be built on {platform.python_implementation()}")
            return
        try:
            super().run()
        except (CompileError, LinkError, CCompilerError,
                DistutilsExecError, DistutilsPlatformError, OSError) as exc:
            self.fall_back_to_python(f"it could not be built: {exc}")

    def fall_back_to_python(self, why: str) -> None:
        """Fall back to the Python implementation, or fail a release wheel build."""
        if _RELEASE_BUILD:
            raise DistutilsPlatformError(
                "the C extension 'wcwidth._wcwidth_c' is required because CIBUILDWHEEL "
                f"is set, but {why}")
        self.warn(f"Skipping optional C extension 'wcwidth._wcwidth_c' because {why}; "
                  "the Python implementation is used.")


setup(
    cmdclass={"build_ext": optional_build_ext},
    ext_modules=_EXT_MODULES,
    options=WHEEL_OPTIONS,
    **_FALLBACK_METADATA,
)