contrib/python-zstandard/setup_zstd.py

windows: add a method to convert Unix style command lines to Windows style

This started as a copy/paste of `os.path.expandvars()`, but limited to a given
dictionary of variables, converting `foo = foo + bar` to `foo += bar`, and
adding 'b' string prefixes.  Then code was added to make sure that a value being
substituted in wouldn't itself be expanded by cmd.exe.  But that left
inconsistent results between `$var1` and `%var1%` when its value was '%foo%'-
since neither were touched, `$var1` wouldn't expand but `%var1%` would.  So
instead, this just converts the Unix style to Windows style (if the variable
exists, because Windows will leave `%missing%` as-is), and lets cmd.exe do its
thing.

I then dropped the %% -> % conversion (because Windows doesn't do this), and
added the ability to escape the '$' with '\'.  The escape character is dropped,
for consistency with shell handling.

After everything seemed stable and working, running the whole test suite flagged
a problem near the end of test-bookmarks.t:1069.  The problem is cmd.exe won't
pass empty variables to its child, so defined but empty variables are now
skipped.  I can't think of anything better, and it seems like a pre-existing
violation of the documentation, which calls out that HG_OLDNODE is empty on
bookmark creation.

Future additions could potentially be replacing strong quotes with double quotes
(cmd.exe doesn't know what to do with the former), escaping a double quote, and
some tilde expansion via os.path.expanduser().  I've got some doubts about
replacing the strong quotes in case sh.exe is run, but it seems like the right
thing to do the vast majority of the time.  The original form of this was
discussed about a year ago[1].

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-July/100735.html

# Copyright (c) 2016-present, Gregory Szorc
# All rights reserved.
#
# This software may be modified and distributed under the terms
# of the BSD license. See the LICENSE file for details.

import distutils.ccompiler
import os
import sys

from distutils.extension import Extension


zstd_sources = ['zstd/%s' % p for p in (
    'common/entropy_common.c',
    'common/error_private.c',
    'common/fse_decompress.c',
    'common/pool.c',
    'common/threading.c',
    'common/xxhash.c',
    'common/zstd_common.c',
    'compress/fse_compress.c',
    'compress/huf_compress.c',
    'compress/zstd_compress.c',
    'compress/zstd_double_fast.c',
    'compress/zstd_fast.c',
    'compress/zstd_lazy.c',
    'compress/zstd_ldm.c',
    'compress/zstd_opt.c',
    'compress/zstdmt_compress.c',
    'decompress/huf_decompress.c',
    'decompress/zstd_decompress.c',
    'dictBuilder/cover.c',
    'dictBuilder/divsufsort.c',
    'dictBuilder/zdict.c',
)]

zstd_sources_legacy = ['zstd/%s' % p for p in (
    'deprecated/zbuff_common.c',
    'deprecated/zbuff_compress.c',
    'deprecated/zbuff_decompress.c',
    'legacy/zstd_v01.c',
    'legacy/zstd_v02.c',
    'legacy/zstd_v03.c',
    'legacy/zstd_v04.c',
    'legacy/zstd_v05.c',
    'legacy/zstd_v06.c',
    'legacy/zstd_v07.c'
)]

zstd_includes = [
    'zstd',
    'zstd/common',
    'zstd/compress',
    'zstd/decompress',
    'zstd/dictBuilder',
]

zstd_includes_legacy = [
    'zstd/deprecated',
    'zstd/legacy',
]

ext_includes = [
    'c-ext',
    'zstd/common',
]

ext_sources = [
    'zstd/common/pool.c',
    'zstd/common/threading.c',
    'zstd.c',
    'c-ext/bufferutil.c',
    'c-ext/compressiondict.c',
    'c-ext/compressobj.c',
    'c-ext/compressor.c',
    'c-ext/compressoriterator.c',
    'c-ext/compressionparams.c',
    'c-ext/compressionreader.c',
    'c-ext/compressionwriter.c',
    'c-ext/constants.c',
    'c-ext/decompressobj.c',
    'c-ext/decompressor.c',
    'c-ext/decompressoriterator.c',
    'c-ext/decompressionreader.c',
    'c-ext/decompressionwriter.c',
    'c-ext/frameparams.c',
]

zstd_depends = [
    'c-ext/python-zstandard.h',
]


def get_c_extension(support_legacy=False, system_zstd=False, name='zstd',
                    warnings_as_errors=False):
    """Obtain a distutils.extension.Extension for the C extension."""
    root = os.path.abspath(os.path.dirname(__file__))

    sources = set([os.path.join(root, p) for p in ext_sources])
    if not system_zstd:
        sources.update([os.path.join(root, p) for p in zstd_sources])
        if support_legacy:
            sources.update([os.path.join(root, p) for p in zstd_sources_legacy])
    sources = list(sources)

    include_dirs = set([os.path.join(root, d) for d in ext_includes])
    if not system_zstd:
        include_dirs.update([os.path.join(root, d) for d in zstd_includes])
        if support_legacy:
            include_dirs.update([os.path.join(root, d) for d in zstd_includes_legacy])
    include_dirs = list(include_dirs)

    depends = [os.path.join(root, p) for p in zstd_depends]

    compiler = distutils.ccompiler.new_compiler()

    # Needed for MSVC.
    if hasattr(compiler, 'initialize'):
        compiler.initialize()

    if compiler.compiler_type == 'unix':
        compiler_type = 'unix'
    elif compiler.compiler_type == 'msvc':
        compiler_type = 'msvc'
    elif compiler.compiler_type == 'mingw32':
        compiler_type = 'mingw32'
    else:
        raise Exception('unhandled compiler type: %s' %
                        compiler.compiler_type)

    extra_args = ['-DZSTD_MULTITHREAD']

    if not system_zstd:
        extra_args.append('-DZSTDLIB_VISIBILITY=')
        extra_args.append('-DZDICTLIB_VISIBILITY=')
        extra_args.append('-DZSTDERRORLIB_VISIBILITY=')

        if compiler_type == 'unix':
            extra_args.append('-fvisibility=hidden')

    if not system_zstd and support_legacy:
        extra_args.append('-DZSTD_LEGACY_SUPPORT=1')

    if warnings_as_errors:
        if compiler_type in ('unix', 'mingw32'):
            extra_args.append('-Werror')
        elif compiler_type == 'msvc':
            extra_args.append('/WX')
        else:
            assert False

    libraries = ['zstd'] if system_zstd else []

    # TODO compile with optimizations.
    return Extension(name, sources,
                     include_dirs=include_dirs,
                     depends=depends,
                     extra_compile_args=extra_args,
                     libraries=libraries)