1 files changed, 172 insertions, 0 deletions
diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
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+++ b/setuptools/build_meta.py
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+"""A PEP 517 interface to setuptools
+
+Previously, when a user or a command line tool (let's call it a "frontend")
+needed to make a request of setuptools to take a certain action, for
+example, generating a list of installation requirements, the frontend would
+would call "setup.py egg_info" or "setup.py bdist_wheel" on the command line.
+
+PEP 517 defines a different method of interfacing with setuptools. Rather
+than calling "setup.py" directly, the frontend should:
+
+  1. Set the current directory to the directory with a setup.py file
+  2. Import this module into a safe python interpreter (one in which
+     setuptools can potentially set global variables or crash hard).
+  3. Call one of the functions defined in PEP 517.
+
+What each function does is defined in PEP 517. However, here is a "casual"
+definition of the functions (this definition should not be relied on for
+bug reports or API stability):
+
+  - `build_wheel`: build a wheel in the folder and return the basename
+  - `get_requires_for_build_wheel`: get the `setup_requires` to build
+  - `prepare_metadata_for_build_wheel`: get the `install_requires`
+  - `build_sdist`: build an sdist in the folder and return the basename
+  - `get_requires_for_build_sdist`: get the `setup_requires` to build
+
+Again, this is not a formal definition! Just a "taste" of the module.
+"""
+
+import os
+import sys
+import tokenize
+import shutil
+import contextlib
+
+import setuptools
+import distutils
+
+
+class SetupRequirementsError(BaseException):
+    def __init__(self, specifiers):
+        self.specifiers = specifiers
+
+
+class Distribution(setuptools.dist.Distribution):
+    def fetch_build_eggs(self, specifiers):
+        raise SetupRequirementsError(specifiers)
+
+    @classmethod
+    @contextlib.contextmanager
+    def patch(cls):
+        """
+        Replace
+        distutils.dist.Distribution with this class
+        for the duration of this context.
+        """
+        orig = distutils.core.Distribution
+        distutils.core.Distribution = cls
+        try:
+            yield
+        finally:
+            distutils.core.Distribution = orig
+
+
+def _run_setup(setup_script='setup.py'):
+    # Note that we can reuse our build directory between calls
+    # Correctness comes first, then optimization later
+    __file__ = setup_script
+    __name__ = '__main__'
+    f = getattr(tokenize, 'open', open)(__file__)
+    code = f.read().replace('\\r\\n', '\\n')
+    f.close()
+    exec(compile(code, __file__, 'exec'), locals())
+
+
+def _fix_config(config_settings):
+    config_settings = config_settings or {}
+    config_settings.setdefault('--global-option', [])
+    return config_settings
+
+
+def _get_build_requires(config_settings):
+    config_settings = _fix_config(config_settings)
+    requirements = ['setuptools', 'wheel']
+
+    sys.argv = sys.argv[:1] + ['egg_info'] + \
+        config_settings["--global-option"]
+    try:
+        with Distribution.patch():
+            _run_setup()
+    except SetupRequirementsError as e:
+        requirements += e.specifiers
+
+    return requirements
+
+
+def _get_immediate_subdirectories(a_dir):
+    return [name for name in os.listdir(a_dir)
+            if os.path.isdir(os.path.join(a_dir, name))]
+
+
+def get_requires_for_build_wheel(config_settings=None):
+    config_settings = _fix_config(config_settings)
+    return _get_build_requires(config_settings)
+
+
+def get_requires_for_build_sdist(config_settings=None):
+    config_settings = _fix_config(config_settings)
+    return _get_build_requires(config_settings)
+
+
+def prepare_metadata_for_build_wheel(metadata_directory, config_settings=None):
+    sys.argv = sys.argv[:1] + ['dist_info', '--egg-base', metadata_directory]
+    _run_setup()
+    
+    dist_info_directory = metadata_directory
+    while True:    
+        dist_infos = [f for f in os.listdir(dist_info_directory)
+                      if f.endswith('.dist-info')]
+
+        if len(dist_infos) == 0 and \
+                len(_get_immediate_subdirectories(dist_info_directory)) == 1:
+            dist_info_directory = os.path.join(
+                dist_info_directory, os.listdir(dist_info_directory)[0])
+            continue
+
+        assert len(dist_infos) == 1
+        break
+
+    # PEP 517 requires that the .dist-info directory be placed in the
+    # metadata_directory. To comply, we MUST copy the directory to the root
+    if dist_info_directory != metadata_directory:
+        shutil.move(
+            os.path.join(dist_info_directory, dist_infos[0]),
+            metadata_directory)
+        shutil.rmtree(dist_info_directory, ignore_errors=True)
+
+    return dist_infos[0]
+
+
+def build_wheel(wheel_directory, config_settings=None,
+                metadata_directory=None):
+    config_settings = _fix_config(config_settings)
+    wheel_directory = os.path.abspath(wheel_directory)
+    sys.argv = sys.argv[:1] + ['bdist_wheel'] + \
+        config_settings["--global-option"]
+    _run_setup()
+    if wheel_directory != 'dist':
+        shutil.rmtree(wheel_directory)
+        shutil.copytree('dist', wheel_directory)
+
+    wheels = [f for f in os.listdir(wheel_directory)
+              if f.endswith('.whl')]
+
+    assert len(wheels) == 1
+    return wheels[0]
+
+
+def build_sdist(sdist_directory, config_settings=None):
+    config_settings = _fix_config(config_settings)
+    sdist_directory = os.path.abspath(sdist_directory)
+    sys.argv = sys.argv[:1] + ['sdist'] + \
+        config_settings["--global-option"]
+    _run_setup()
+    if sdist_directory != 'dist':
+        shutil.rmtree(sdist_directory)
+        shutil.copytree('dist', sdist_directory)
+
+    sdists = [f for f in os.listdir(sdist_directory)
+              if f.endswith('.tar.gz')]
+
+    assert len(sdists) == 1
+    return sdists[0]