project.boost: factor out everything else

I finally snapped. This starts to resemble sensible structure though.

9 files changed, 420 insertions, 373 deletions

diff --git a/.ci/Makefile b/.ci/Makefile
index 13fa74f..bfc2917 100644
--- a/.ci/Makefile
+++ b/.ci/Makefile
@@ -186,11 +186,11 @@ echo/boost/%/finished: FORCE
 
 .PHONY: boost/58/download
 boost/58/download: echo/boost/58/build
-	"$(python)" -m project.boost.build download 1.58.0
+	"$(python)" -m project.boost.download 1.58.0
 
 .PHONY: boost/58/build
 boost/58/build:
-	"$(python)" -m project.boost.build build --configuration Debug --platform x86 --link static -- ./boost_1_58_0 --with-filesystem --with-program_options $(b2_flags)
+	"$(python)" -m project.boost.build --configuration Debug --platform x86 --link static -- ./boost_1_58_0 --with-filesystem --with-program_options $(b2_flags)
 
 .PHONY: boost/58/ls
 boost/58/ls: echo/boost/58/ls
@@ -223,11 +223,11 @@ boost/58: boost/58/download boost/58/build boost/58/ls boost/58/exe echo/boost/5
 
 .PHONY: boost/72/download
 boost/72/download: echo/boost/72/build
-	"$(python)" -m project.boost.build download --cache . 1.72.0
+	"$(python)" -m project.boost.download --cache . 1.72.0
 
 .PHONY: boost/72/build
 boost/72/build:
-	"$(python)" -m project.boost.build build --platform x86 x64 --link shared -- ./boost_1_72_0 --with-filesystem --with-program_options $(b2_flags)
+	"$(python)" -m project.boost.build --platform x86 x64 --link shared -- ./boost_1_72_0 --with-filesystem --with-program_options $(b2_flags)
 
 .PHONY: boost/72/ls
 boost/72/ls: echo/boost/72/ls
diff --git a/.pylintrc b/.pylintrc
index 81d8b4e..bccfc70 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -1,5 +1,3 @@
 [MESSAGES CONTROL]
 
 disable=invalid-name,missing-docstring
-
-ignored-modules=build
diff --git a/project/boost/archive.py b/project/boost/archive.py
new file mode 100644
index 0000000..55d05f2
--- /dev/null
+++ b/project/boost/archive.py
@@ -0,0 +1,87 @@
+# Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cmake-common" project.
+# For details, see https://github.com/egor-tensin/cmake-common.
+# Distributed under the MIT License.
+
+import abc
+from contextlib import contextmanager
+import logging
+import os.path
+import shutil
+import tempfile
+
+from project.boost.directory import BoostDir
+
+
+class Archive:
+    def __init__(self, version, path):
+        self.version = version
+        self.path = path
+
+    @property
+    def dir_name(self):
+        return self.version.dir_name
+
+    def unpack(self, dest_dir):
+        path = os.path.join(dest_dir, self.dir_name)
+        if os.path.exists(path):
+            raise RuntimeError(f'Boost directory already exists: {path}')
+        logging.info('Unpacking Boost to: %s', path)
+        shutil.unpack_archive(self.path, dest_dir)
+        return BoostDir(path)
+
+
+class ArchiveStorage(abc.ABC):
+    @abc.abstractmethod
+    def get_archive(self, version):
+        pass
+
+    @contextmanager
+    @abc.abstractmethod
+    def write_archive(self, version, contents):
+        pass
+
+
+class PermanentStorage(ArchiveStorage):
+    def __init__(self, cache_dir):
+        self._dir = cache_dir
+
+    def _archive_path(self, version):
+        return os.path.join(self._dir, version.archive_name)
+
+    def get_archive(self, version):
+        path = self._archive_path(version)
+        if os.path.exists(path):
+            return path
+        return None
+
+    @contextmanager
+    def write_archive(self, version, contents):
+        path = self._archive_path(version)
+        logging.info('Writing Boost archive: %s', path)
+        if os.path.exists(path):
+            raise RuntimeError(f'cannot download Boost, file already exists: {path}')
+        with open(path, mode='w+b') as dest:
+            dest.write(contents)
+        yield path
+
+
+class TemporaryStorage(ArchiveStorage):
+    def __init__(self, temp_dir):
+        self._dir = temp_dir
+
+    def get_archive(self, version):
+        return None
+
+    @contextmanager
+    def write_archive(self, version, contents):
+        with tempfile.NamedTemporaryFile(prefix=f'boost_{version}_', suffix=version.archive_ext,
+                                         dir=self._dir, delete=False) as dest:
+            path = dest.name
+            logging.info('Writing Boost archive: %s', path)
+            dest.write(contents)
+        try:
+            yield path
+        finally:
+            logging.info('Removing temporary Boost archive: %s', path)
+            os.remove(path)
diff --git a/project/boost/build.py b/project/boost/build.py
index e9f2ffc..541e2ba 100644
--- a/project/boost/build.py
+++ b/project/boost/build.py
@@ -1,240 +1,59 @@
-#!/usr/bin/env python3
-
 # Copyright (c) 2019 Egor Tensin <Egor.Tensin@gmail.com>
 # This file is part of the "cmake-common" project.
 # For details, see https://github.com/egor-tensin/cmake-common.
 # Distributed under the MIT License.
 
-'''Download & build Boost.
-
-This script downloads and builds the Boost libraries.  It's main purpose is to:
-1) provide a cross-platform way to download & unpack the Boost distribution
-archive,
-2) set the correct --stagedir parameter value to avoid name clashes.
+R'''Build Boost.
 
-Please pick a command below.  You can execute `%(prog)s COMMAND --help` to view
-its usage message.
+This script builds the Boost libraries.  It's main utility is setting the
+correct --stagedir parameter value to avoid name clashes.
 
-A simple usage example:
+Usage examples:
 
-    $ %(prog)s download 1.71.0
-    ...
 
-    $ %(prog)s build -- boost_1_71_0/ --with-filesystem --with-program_options
+    $ %(prog)s -- boost_1_71_0/ --with-filesystem --with-program_options
     ...
 '''
 
-import abc
 import argparse
-from collections import namedtuple
 from contextlib import contextmanager
-from enum import Enum
-from functools import total_ordering
 import logging
 import os.path
-import platform
-import re
-import shutil
-import subprocess
 import sys
 import tempfile
-import urllib.request
 
-from project.boost.version import Version
+from project.boost.directory import BoostDir
 from project.configuration import Configuration
 from project.linkage import Linkage
 from project.platform import Platform
-
-
-@contextmanager
-def _chdir(path):
-    cwd = os.getcwd()
-    os.chdir(path)
-    try:
-        yield
-    finally:
-        os.chdir(cwd)
-
-
-def _setup_logging():
-    logging.basicConfig(
-        format='%(asctime)s | %(levelname)s | %(message)s',
-        level=logging.INFO)
-
-
-def _on_windows():
-    return platform.system() == 'Windows'
-
-
-def _on_linux():
-    return not _on_windows()
-
-
-def _run_executable(cmd_line):
-    logging.info('Running executable: %s', cmd_line)
-    return subprocess.run(cmd_line, check=True)
-
-
-class BoostArchive:
-    def __init__(self, version, path):
-        self.version = version
-        self.path = path
-
-    @property
-    def dir_name(self):
-        return self.version.dir_name
-
-    def unpack(self, dest_dir):
-        path = os.path.join(dest_dir, self.dir_name)
-        if os.path.exists(path):
-            raise RuntimeError(f'Boost directory already exists: {path}')
-        logging.info('Unpacking Boost to: %s', path)
-        shutil.unpack_archive(self.path, dest_dir)
-        return BoostDir(path)
-
-
-class ArchiveStorage(abc.ABC):
-    @contextmanager
-    def download(self, version):
-        path = self.get_archive(version)
-        if path is not None:
-            logging.info('Using existing Boost archive: %s', path)
-            yield BoostArchive(version, path)
-            return
-
-        urls = version.get_download_urls()
-
-        for url in urls:
-            logging.info('Trying URL: %s', url)
-            try:
-                with urllib.request.urlopen(url, timeout=20) as request:
-                    with self.write_archive(version, request.read()) as path:
-                        yield BoostArchive(version, path)
-                        return
-            except urllib.request.URLError as e:
-                logging.error("Couldn't download from this mirror, an error occured:")
-                logging.exception(e)
-
-        raise RuntimeError("Couldn't download Boost from any of the mirrors")
-
-    @abc.abstractmethod
-    def get_archive(self, version):
-        pass
-
-    @contextmanager
-    @abc.abstractmethod
-    def write_archive(self, version, contents):
-        pass
-
-
-class CacheStorage(ArchiveStorage):
-    def __init__(self, cache_dir):
-        self._dir = cache_dir
-
-    def _archive_path(self, version):
-        return os.path.join(self._dir, version.archive_name)
-
-    def get_archive(self, version):
-        path = self._archive_path(version)
-        if os.path.exists(path):
-            return path
-        return None
-
-    @contextmanager
-    def write_archive(self, version, contents):
-        path = self._archive_path(version)
-        logging.info('Writing Boost archive: %s', path)
-        if os.path.exists(path):
-            raise RuntimeError(f'cannot download Boost, file already exists: {path}')
-        with open(path, mode='w+b') as dest:
-            dest.write(contents)
-        yield path
-
-
-class TempStorage(ArchiveStorage):
-    def __init__(self, temp_dir):
-        self._dir = temp_dir
-
-    def get_archive(self, version):
-        return None
-
-    @contextmanager
-    def write_archive(self, version, contents):
-        with tempfile.NamedTemporaryFile(prefix=f'boost_{version}_', suffix=version.archive_ext, dir=self._dir, delete=False) as dest:
-            path = dest.name
-            logging.info('Writing Boost archive: %s', path)
-            dest.write(contents)
-        try:
-            yield path
-        finally:
-            logging.info('Removing temporary Boost archive: %s', path)
-            os.remove(path)
-
-
-class BoostDir:
-    def __init__(self, path):
-        if not os.path.isdir(path):
-            raise RuntimeError(f"Boost directory doesn't exist: {path}")
-        self.path = path
-
-    def _go(self):
-        return _chdir(self.path)
-
-    def build(self, params):
-        with self._go():
-            self._bootstrap_if_required()
-            self._b2(params)
-
-    def _bootstrap_if_required(self):
-        if os.path.isfile(self._b2_path()):
-            logging.info('Not going to bootstrap, b2 is already there')
-            return
-        self.bootstrap()
-
-    def bootstrap(self):
-        with self._go():
-            _run_executable(self._bootstrap_path())
-
-    def _b2(self, params):
-        for b2_params in params.enum_b2_args():
-            _run_executable([self._b2_path()] + b2_params)
-
-    @staticmethod
-    def _bootstrap_path():
-        return os.path.join('.', BoostDir._bootstrap_name())
-
-    @staticmethod
-    def _bootstrap_name():
-        ext = '.sh'
-        if _on_windows():
-            ext = '.bat'
-        return f'bootstrap{ext}'
-
-    @staticmethod
-    def _b2_path():
-        return os.path.join('.', BoostDir._b2_name())
-
-    @staticmethod
-    def _b2_name():
-        ext = ''
-        if _on_windows():
-            ext = '.exe'
-        return f'b2{ext}'
+import project.utils
 
 
 class BuildParameters:
-    def __init__(self, args):
-        self.platforms = args.platforms or Platform.all()
-        self.configurations = args.configurations or Configuration.all()
-        self.link = args.link or Linkage.all()
-        self.runtime_link = args.runtime_link
-
+    def __init__(self, boost_dir, build_dir=None, platforms=None, configurations=None, link=None,
+                 runtime_link=None, b2_args=None):
+
+        boost_dir = project.utils.normalize_path(boost_dir)
+        if build_dir is not None:
+            build_dir = project.utils.normalize_path(build_dir)
+        platforms = platforms or Platform.all()
+        configurations = configurations or Configuration.all()
+        link = link or Linkage.all()
+        runtime_link = runtime_link or Linkage.STATIC
+        b2_args = b2_args or []
+
+        self.boost_dir = boost_dir
         self.stage_dir = 'stage'
+        self.build_dir = build_dir
+        self.platforms = platforms
+        self.configurations = configurations
+        self.link = link
+        self.runtime_link = runtime_link
+        self.b2_args = b2_args
 
-        self.build_dir = args.build_dir
-        self.boost_dir = args.boost_dir
-
-        self.b2_args = args.b2_args
+    @staticmethod
+    def from_args(args):
+        return BuildParameters(**vars(args))
 
     def enum_b2_args(self):
         with self._create_build_dir() as build_dir:
@@ -250,7 +69,7 @@ class BuildParameters:
                 if link is Linkage.SHARED:
                     logging.warning("Cannot link the runtime statically to a dynamic library, going to link dynamically")
                     runtime_link = Linkage.SHARED
-                elif _on_linux():
+                elif project.utils.on_linux():
                     logging.warning("Cannot link to the GNU C Library (which is assumed) statically, going to link dynamically")
                     runtime_link = Linkage.SHARED
             yield link, runtime_link
@@ -316,8 +135,9 @@ class BuildParameters:
         return f'variant={configuration.to_boost_variant()}'
 
 
-def _parse_dir(s):
-    return os.path.abspath(os.path.normpath(s))
+def build(params):
+    boost_dir = BoostDir(params.boost_dir)
+    boost_dir.build(params)
 
 
 def _parse_args(argv=None):
@@ -329,93 +149,45 @@ def _parse_args(argv=None):
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter)
 
-    subparsers = parser.add_subparsers(dest='command')
-
-    download = subparsers.add_parser('download', help='download & bootstrap Boost')
-
-    download.add_argument('--cache', metavar='DIR', dest='cache_dir',
-                          type=_parse_dir,
-                          help='download directory (temporary file unless specified)')
-    download.add_argument('--unpack', metavar='DIR', dest='unpack_dir',
-                          type=_parse_dir, default='.',
-                          help='directory to unpack the archive to')
-    download.add_argument('boost_version', metavar='VERSION',
-                          type=Version.from_string,
-                          help='Boost version (in the MAJOR.MINOR.PATCH format)')
-
-    build = subparsers.add_parser('build', help='build the libraries')
-
     # These are used to put the built libraries into proper stage/
     # subdirectories (to avoid name clashes).
-    build.add_argument('--platform', metavar='PLATFORM',
-                       nargs='*', dest='platforms', default=[],
-                       type=Platform.parse,
-                       help=f'target platform ({"/".join(map(str, Platform))})')
-    build.add_argument('--configuration', metavar='CONFIGURATION',
-                       nargs='*', dest='configurations', default=[],
-                       type=Configuration.parse,
-                       help=f'target configuration ({"/".join(map(str, Configuration))})')
+    parser.add_argument('--platform', metavar='PLATFORM',
+                        nargs='*', dest='platforms', default=[],
+                        type=Platform.parse,
+                        help=f'target platform ({"/".join(map(str, Platform))})')
+    parser.add_argument('--configuration', metavar='CONFIGURATION',
+                        nargs='*', dest='configurations', default=[],
+                        type=Configuration.parse,
+                        help=f'target configuration ({"/".join(map(str, Configuration))})')
     # This is needed because the default behaviour on Linux and Windows is
     # different: static & dynamic libs are built on Linux, but only static libs
     # are built on Windows by default.
-    build.add_argument('--link', metavar='LINKAGE',
-                       nargs='*', default=[],
-                       type=Linkage.parse,
-                       help=f'how the libraries are linked ({"/".join(map(str, Linkage))})')
+    parser.add_argument('--link', metavar='LINKAGE',
+                        nargs='*', default=[],
+                        type=Linkage.parse,
+                        help=f'how the libraries are linked ({"/".join(map(str, Linkage))})')
     # This is used to omit runtime-link=static I'd have to otherwise use a lot,
     # plus the script validates the link= and runtime-link= combinations.
-    build.add_argument('--runtime-link', metavar='LINKAGE',
-                       type=Linkage.parse, default=Linkage.STATIC,
-                       help=f'how the libraries link to the runtime ({"/".join(map(str, Linkage))})')
-
-    build.add_argument('--build', metavar='DIR', dest='build_dir',
-                       type=_parse_dir,
-                       help='Boost build directory (temporary directory unless specified)')
-    build.add_argument('boost_dir', metavar='DIR',
-                       type=_parse_dir,
-                       help='root Boost directory')
-
-    build.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
-                       help='additional b2 arguments, to be passed verbatim')
-
-    args = parser.parse_args(argv)
-    if args.command is None:
-        parser.error("please specify a command")
-    return args
-
-
-def build(args):
-    build_params = BuildParameters(args)
-    boost_dir = BoostDir(args.boost_dir)
-    boost_dir.build(build_params)
-
+    parser.add_argument('--runtime-link', metavar='LINKAGE',
+                        type=Linkage.parse, default=Linkage.STATIC,
+                        help=f'how the libraries link to the runtime ({"/".join(map(str, Linkage))})')
 
-def download(args):
-    storage = TempStorage(args.unpack_dir)
-    if args.cache_dir is not None:
-        storage = CacheStorage(args.cache_dir)
-    with storage.download(args.boost_version) as archive:
-        boost_dir = archive.unpack(args.unpack_dir)
-        boost_dir.bootstrap()
+    parser.add_argument('--build', metavar='DIR', dest='build_dir',
+                        type=project.utils.normalize_path,
+                        help='Boost build directory (temporary directory unless specified)')
+    parser.add_argument('boost_dir', metavar='DIR',
+                        type=project.utils.normalize_path,
+                        help='root Boost directory')
 
+    parser.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
+                        help='additional b2 arguments, to be passed verbatim')
 
-def main(argv=None):
-    args = _parse_args(argv)
-    if args.command == 'download':
-        download(args)
-    elif args.command == 'build':
-        build(args)
-    else:
-        raise NotImplementedError(f'unsupported command: {args.command}')
+    return parser.parse_args(argv)
 
 
 def _main(argv=None):
-    _setup_logging()
-    try:
-        main(argv)
-    except Exception as e:
-        logging.exception(e)
-        raise
+    with project.utils.setup_logging():
+        build(BuildParameters.from_args(_parse_args(argv)))
 
 
 if __name__ == '__main__':
diff --git a/project/boost/directory.py b/project/boost/directory.py
new file mode 100644
index 0000000..e50041f
--- /dev/null
+++ b/project/boost/directory.py
@@ -0,0 +1,60 @@
+# Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cmake-common" project.
+# For details, see https://github.com/egor-tensin/cmake-common.
+# Distributed under the MIT License.
+
+import logging
+import os.path
+
+from project.utils import cd, run, on_windows
+
+
+class BoostDir:
+    def __init__(self, path):
+        if not os.path.isdir(path):
+            raise RuntimeError(f"Boost directory doesn't exist: {path}")
+        self.path = path
+
+    def _go(self):
+        return cd(self.path)
+
+    def build(self, params):
+        with self._go():
+            self._bootstrap_if_required()
+            self._b2(params)
+
+    def _bootstrap_if_required(self):
+        if os.path.isfile(self._b2_path()):
+            logging.info('Not going to bootstrap, b2 is already there')
+            return
+        self.bootstrap()
+
+    def bootstrap(self):
+        with self._go():
+            run(self._bootstrap_path())
+
+    def _b2(self, params):
+        for b2_params in params.enum_b2_args():
+            run([self._b2_path()] + b2_params)
+
+    @staticmethod
+    def _bootstrap_path():
+        return os.path.join('.', BoostDir._bootstrap_name())
+
+    @staticmethod
+    def _bootstrap_name():
+        ext = '.sh'
+        if on_windows():
+            ext = '.bat'
+        return f'bootstrap{ext}'
+
+    @staticmethod
+    def _b2_path():
+        return os.path.join('.', BoostDir._b2_name())
+
+    @staticmethod
+    def _b2_name():
+        ext = ''
+        if on_windows():
+            ext = '.exe'
+        return f'b2{ext}'
diff --git a/project/boost/download.py b/project/boost/download.py
new file mode 100644
index 0000000..954ec1f
--- /dev/null
+++ b/project/boost/download.py
@@ -0,0 +1,112 @@
+# Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cmake-common" project.
+# For details, see https://github.com/egor-tensin/cmake-common.
+# Distributed under the MIT License.
+
+R'''Download & bootstrap Boost.
+
+This script downloads and bootstraps a Boost distribution.  It's main utility
+is that it's supposed to be cross-platform.
+
+Usage examples:
+
+    $ %(prog)s 1.71.0
+    ...
+
+    $ %(prog)s --unpack ~/workspace/third-party/ 1.65.0
+    ...
+'''
+
+import argparse
+from contextlib import contextmanager
+import logging
+import sys
+import urllib.request
+
+from project.boost.archive import Archive, PermanentStorage, TemporaryStorage
+from project.boost.version import Version
+import project.utils
+
+
+def _download_try_url(url):
+    logging.info('Trying URL: %s', url)
+    try:
+        with urllib.request.urlopen(url, timeout=20) as request:
+            return request.read()
+    except urllib.request.URLError as e:
+        logging.error("Couldn't download from this mirror, an error occured:")
+        logging.exception(e)
+
+
+@contextmanager
+def _download_try_all_urls(version, storage):
+    urls = version.get_download_urls()
+    for url in urls:
+        reply = _download_try_url(url)
+        if reply is None:
+            continue
+        with storage.write_archive(version, reply) as path:
+            yield path
+            return
+    raise RuntimeError("Couldn't download Boost from any of the mirrors")
+
+
+@contextmanager
+def _download_if_necessary(version, storage):
+    path = storage.get_archive(version)
+    if path is not None:
+        logging.info('Using existing Boost archive: %s', path)
+        yield path
+        return
+    with _download_try_all_urls(version, storage) as path:
+        yield path
+
+
+class DownloadParameters:
+    def __init__(self, version, unpack_dir='.', cache_dir=None):
+        self.version = version
+        self.unpack_dir = project.utils.normalize_path(unpack_dir)
+        self.storage = TemporaryStorage(unpack_dir)
+        if cache_dir is not None:
+            cache_dir = project.utils.normalize_path(cache_dir)
+            self.storage = PermanentStorage(cache_dir)
+
+    @staticmethod
+    def from_args(args):
+        return DownloadParameters(**vars(args))
+
+
+def download(params):
+    with _download_if_necessary(params.version, params.storage) as path:
+        archive = Archive(params.version, path)
+        boost_dir = archive.unpack(params.unpack_dir)
+        boost_dir.bootstrap()
+
+
+def _parse_args(argv=None):
+    if argv is None:
+        argv = sys.argv[1:]
+    logging.info('Command line arguments: %s', argv)
+
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        formatter_class=argparse.RawDescriptionHelpFormatter)
+
+    parser.add_argument('--unpack', metavar='DIR', dest='unpack_dir',
+                        type=project.utils.normalize_path, default='.',
+                        help='directory to unpack the archive to')
+    parser.add_argument('--cache', metavar='DIR', dest='cache_dir',
+                        type=project.utils.normalize_path,
+                        help='download directory (temporary file unless specified)')
+    parser.add_argument('version', metavar='VERSION', type=Version.from_string,
+                        help='Boost version (in the MAJOR.MINOR.PATCH format)')
+    return parser.parse_args(argv)
+
+
+def _main(argv=None):
+    with project.utils.setup_logging():
+        download(DownloadParameters.from_args(_parse_args(argv)))
+
+
+if __name__ == '__main__':
+    _main()
diff --git a/project/ci/appveyor/boost.py b/project/ci/appveyor/boost.py
index aa2d77a..0a15b7b 100644
--- a/project/ci/appveyor/boost.py
+++ b/project/ci/appveyor/boost.py
@@ -1,11 +1,9 @@
-#!/usr/bin/env python3
-
 # Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
 # This file is part of the "cmake-common" project.
 # For details, see https://github.com/egor-tensin/cmake-common.
 # Distributed under the MIT License.
 
-'''Download & build Boost on AppVeyor.
+R'''Download & build Boost on AppVeyor.
 
 This is similar to build.py, but auto-fills some parameters for build.py from
 the AppVeyor-defined environment variables.  This script is rarely usefull,
@@ -22,7 +20,12 @@ import os.path
 import sys
 
 from project.boost.version import Version
-from project.boost.build import main as build_main
+from project.boost.download import DownloadParameters, download
+from project.boost.build import BuildParameters, build
+from project.configuration import Configuration
+from project.linkage import Linkage
+from project.platform import Platform
+import project.utils
 
 
 def _env(name):
@@ -37,7 +40,7 @@ def _check_appveyor():
 
 
 def _get_build_dir():
-    return 'C:\\projects'
+    return R'C:\projects'
 
 
 def _get_boost_dir():
@@ -45,21 +48,15 @@ def _get_boost_dir():
 
 
 def _get_boost_version():
-    return _env('appveyor_boost_version')
+    return Version.from_string(_env('appveyor_boost_version'))
 
 
 def _get_configuration():
-    return _env('CONFIGURATION')
+    return Configuration.parse(_env('CONFIGURATION'))
 
 
 def _get_platform():
-    return _env('PLATFORM')
-
-
-def _setup_logging():
-    logging.basicConfig(
-        format='%(asctime)s | %(levelname)s | %(message)s',
-        level=logging.INFO)
+    return Platform.parse(_env('PLATFORM'))
 
 
 def _parse_args(argv=None):
@@ -70,9 +67,9 @@ def _parse_args(argv=None):
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter)
-    parser.add_argument('--link', metavar='LINKAGE', nargs='*',
+    parser.add_argument('--link', metavar='LINKAGE', nargs='*', type=Linkage.parse,
                         help='how the libraries are linked (i.e. static/shared)')
-    parser.add_argument('--runtime-link', metavar='LINKAGE',
+    parser.add_argument('--runtime-link', metavar='LINKAGE', type=Linkage.parse,
                         help='how the libraries link to the runtime')
     parser.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
                         help='additional b2 arguments, to be passed verbatim')
@@ -83,39 +80,26 @@ def build_appveyor(argv=None):
     args = _parse_args(argv)
     _check_appveyor()
 
-    version = Version.from_string(_get_boost_version())
-    appveyor_argv = [
-        'download',
-        '--unpack', _get_build_dir(),
-        '--', str(version)
-    ]
-    build_main(appveyor_argv)
+    version = _get_boost_version()
+    build_dir = _get_build_dir()
+    download(DownloadParameters(version, unpack_dir=build_dir))
 
-    unpacked_boost_dir = version.dir_path(_get_build_dir())
+    unpacked_boost_dir = version.dir_path(build_dir)
     boost_dir = _get_boost_dir()
     os.rename(unpacked_boost_dir, boost_dir)
 
-    appveyor_argv = [
-        'build',
-        '--configuration', _get_configuration(),
-        '--platform', _get_platform(),
-    ]
-    if args.link is not None:
-        appveyor_argv.append('--link')
-        appveyor_argv += args.link
-    if args.runtime_link is not None:
-        appveyor_argv += ['--runtime-link', args.runtime_link]
-    appveyor_argv += ['--', boost_dir]
-    build_main(appveyor_argv + args.b2_args)
+    params = BuildParameters(boost_dir,
+                             platforms=(_get_platform(),),
+                             configurations=(_get_configuration(),),
+                             link=args.link,
+                             runtime_link=args.runtime_link,
+                             b2_args=args.b2_args)
+    build(params)
 
 
 def main(argv=None):
-    _setup_logging()
-    try:
+    with project.utils.setup_logging():
         build_appveyor(argv)
-    except Exception as e:
-        logging.exception(e)
-        raise
 
 
 if __name__ == '__main__':
diff --git a/project/ci/travis/boost.py b/project/ci/travis/boost.py
index 6d3e911..b8e843f 100644
--- a/project/ci/travis/boost.py
+++ b/project/ci/travis/boost.py
@@ -1,11 +1,9 @@
-#!/usr/bin/env python3
-
 # Copyright (c) 2019 Egor Tensin <Egor.Tensin@gmail.com>
 # This file is part of the "cmake-common" project.
 # For details, see https://github.com/egor-tensin/cmake-common.
 # Distributed under the MIT License.
 
-'''Download & build Boost on Travis.
+R'''Download & build Boost on Travis.
 
 This is similar to build.py, but auto-fills some parameters for build.py from
 the Travis-defined environment variables.
@@ -20,7 +18,12 @@ import os.path
 import sys
 
 from project.boost.version import Version
-from project.boost.build import main as build_main
+from project.boost.download import DownloadParameters, download
+from project.boost.build import BuildParameters, build
+from project.configuration import Configuration
+from project.linkage import Linkage
+from project.platform import Platform
+import project.utils
 
 
 def _env(name):
@@ -43,21 +46,15 @@ def _get_boost_dir():
 
 
 def _get_boost_version():
-    return _env('travis_boost_version')
+    return Version.from_string(_env('travis_boost_version'))
 
 
 def _get_configuration():
-    return _env('configuration')
+    return Configuration.parse(_env('configuration'))
 
 
 def _get_platform():
-    return _env('platform')
-
-
-def _setup_logging():
-    logging.basicConfig(
-        format='%(asctime)s | %(levelname)s | %(message)s',
-        level=logging.INFO)
+    return Platform.parse(_env('platform'))
 
 
 def _parse_args(argv=None):
@@ -68,9 +65,9 @@ def _parse_args(argv=None):
     parser = argparse.ArgumentParser(
         description=__doc__,
         formatter_class=argparse.RawDescriptionHelpFormatter)
-    parser.add_argument('--link', metavar='LINKAGE', nargs='*',
+    parser.add_argument('--link', metavar='LINKAGE', nargs='*', type=Linkage.parse,
                         help='how the libraries are linked')
-    parser.add_argument('--runtime-link', metavar='LINKAGE',
+    parser.add_argument('--runtime-link', metavar='LINKAGE', type=Linkage.parse,
                         help='how the libraries link to the runtime')
     parser.add_argument('b2_args', nargs='*', metavar='B2_ARG', default=[],
                         help='additional b2 arguments, to be passed verbatim')
@@ -81,39 +78,26 @@ def build_travis(argv=None):
     args = _parse_args(argv)
     _check_travis()
 
-    version = Version.from_string(_get_boost_version())
-    travis_argv = [
-        'download',
-        '--unpack', _get_build_dir(),
-        '--', str(version)
-    ]
-    build_main(travis_argv)
+    version = _get_boost_version()
+    build_dir = _get_build_dir()
+    download(DownloadParameters(version, unpack_dir=build_dir))
 
     unpacked_boost_dir = version.dir_path(_get_build_dir())
     boost_dir = _get_boost_dir()
     os.rename(unpacked_boost_dir, boost_dir)
 
-    travis_argv = [
-        'build',
-        '--configuration', _get_configuration(),
-        '--platform', _get_platform(),
-    ]
-    if args.link is not None:
-        travis_argv.append('--link')
-        travis_argv += args.link
-    if args.runtime_link is not None:
-        travis_argv += ['--runtime-link', args.runtime_link]
-    travis_argv += ['--', boost_dir]
-    build_main(travis_argv + args.b2_args)
+    params = BuildParameters(boost_dir,
+                             platforms=(_get_platform(),),
+                             configurations=(_get_configuration(),),
+                             link=args.link,
+                             runtime_link=args.runtime_link,
+                             b2_args=args.b2_args)
+    build(params)
 
 
 def main(argv=None):
-    _setup_logging()
-    try:
+    with project.utils.setup_logging():
         build_travis(argv)
-    except Exception as e:
-        logging.exception(e)
-        raise
 
 
 if __name__ == '__main__':
diff --git a/project/utils.py b/project/utils.py
new file mode 100644
index 0000000..a766f90
--- /dev/null
+++ b/project/utils.py
@@ -0,0 +1,50 @@
+# Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
+# This file is part of the "cmake-common" project.
+# For details, see https://github.com/egor-tensin/cmake-common.
+# Distributed under the MIT License.
+
+from contextlib import contextmanager
+import logging
+import os.path
+import platform
+import subprocess
+
+
+def normalize_path(s):
+    return os.path.abspath(os.path.normpath(s))
+
+
+@contextmanager
+def setup_logging():
+    logging.basicConfig(
+        format='%(asctime)s | %(levelname)s | %(message)s',
+        datefmt='%Y-%m-%d %H:%M:%S',
+        level=logging.INFO)
+    try:
+        yield
+    except Exception as e:
+        logging.exception(e)
+        raise
+
+
+@contextmanager
+def cd(path):
+    cwd = os.getcwd()
+    os.chdir(path)
+    try:
+        yield
+    finally:
+        os.chdir(cwd)
+
+
+def run(cmd_line):
+    logging.info('Running executable: %s', cmd_line)
+    return subprocess.run(cmd_line, check=True)
+
+
+def on_windows():
+    return platform.system() == 'Windows'
+
+
+def on_linux():
+    return not on_windows()