252 lines
7.6 KiB
Python
252 lines
7.6 KiB
Python
"""
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Build a c-extension module on-the-fly in tests.
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See build_and_import_extensions for usage hints
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"""
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import os
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import pathlib
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import sys
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import sysconfig
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__all__ = ['build_and_import_extension', 'compile_extension_module']
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def build_and_import_extension(
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modname, functions, *, prologue="", build_dir=None,
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include_dirs=[], more_init=""):
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"""
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Build and imports a c-extension module `modname` from a list of function
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fragments `functions`.
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Parameters
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----------
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functions : list of fragments
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Each fragment is a sequence of func_name, calling convention, snippet.
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prologue : string
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Code to precede the rest, usually extra ``#include`` or ``#define``
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macros.
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build_dir : pathlib.Path
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Where to build the module, usually a temporary directory
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include_dirs : list
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Extra directories to find include files when compiling
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more_init : string
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Code to appear in the module PyMODINIT_FUNC
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Returns
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-------
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out: module
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The module will have been loaded and is ready for use
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Examples
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--------
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>>> functions = [("test_bytes", "METH_O", \"\"\"
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if ( !PyBytesCheck(args)) {
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Py_RETURN_FALSE;
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}
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Py_RETURN_TRUE;
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\"\"\")]
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>>> mod = build_and_import_extension("testme", functions)
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>>> assert not mod.test_bytes(u'abc')
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>>> assert mod.test_bytes(b'abc')
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"""
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from distutils.errors import CompileError
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body = prologue + _make_methods(functions, modname)
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init = """PyObject *mod = PyModule_Create(&moduledef);
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"""
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if not build_dir:
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build_dir = pathlib.Path('.')
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if more_init:
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init += """#define INITERROR return NULL
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"""
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init += more_init
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init += "\nreturn mod;"
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source_string = _make_source(modname, init, body)
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try:
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mod_so = compile_extension_module(
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modname, build_dir, include_dirs, source_string)
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except CompileError as e:
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# shorten the exception chain
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raise RuntimeError(f"could not compile in {build_dir}:") from e
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import importlib.util
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spec = importlib.util.spec_from_file_location(modname, mod_so)
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foo = importlib.util.module_from_spec(spec)
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spec.loader.exec_module(foo)
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return foo
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def compile_extension_module(
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name, builddir, include_dirs,
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source_string, libraries=[], library_dirs=[]):
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"""
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Build an extension module and return the filename of the resulting
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native code file.
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Parameters
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----------
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name : string
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name of the module, possibly including dots if it is a module inside a
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package.
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builddir : pathlib.Path
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Where to build the module, usually a temporary directory
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include_dirs : list
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Extra directories to find include files when compiling
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libraries : list
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Libraries to link into the extension module
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library_dirs: list
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Where to find the libraries, ``-L`` passed to the linker
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"""
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modname = name.split('.')[-1]
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dirname = builddir / name
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dirname.mkdir(exist_ok=True)
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cfile = _convert_str_to_file(source_string, dirname)
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include_dirs = include_dirs + [sysconfig.get_config_var('INCLUDEPY')]
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return _c_compile(
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cfile, outputfilename=dirname / modname,
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include_dirs=include_dirs, libraries=[], library_dirs=[],
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)
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def _convert_str_to_file(source, dirname):
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"""Helper function to create a file ``source.c`` in `dirname` that contains
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the string in `source`. Returns the file name
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"""
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filename = dirname / 'source.c'
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with filename.open('w') as f:
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f.write(str(source))
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return filename
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def _make_methods(functions, modname):
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""" Turns the name, signature, code in functions into complete functions
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and lists them in a methods_table. Then turns the methods_table into a
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``PyMethodDef`` structure and returns the resulting code fragment ready
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for compilation
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"""
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methods_table = []
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codes = []
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for funcname, flags, code in functions:
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cfuncname = "%s_%s" % (modname, funcname)
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if 'METH_KEYWORDS' in flags:
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signature = '(PyObject *self, PyObject *args, PyObject *kwargs)'
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else:
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signature = '(PyObject *self, PyObject *args)'
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methods_table.append(
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"{\"%s\", (PyCFunction)%s, %s}," % (funcname, cfuncname, flags))
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func_code = """
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static PyObject* {cfuncname}{signature}
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{{
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{code}
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}}
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""".format(cfuncname=cfuncname, signature=signature, code=code)
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codes.append(func_code)
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body = "\n".join(codes) + """
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static PyMethodDef methods[] = {
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%(methods)s
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{ NULL }
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};
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static struct PyModuleDef moduledef = {
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PyModuleDef_HEAD_INIT,
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"%(modname)s", /* m_name */
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NULL, /* m_doc */
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-1, /* m_size */
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methods, /* m_methods */
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};
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""" % dict(methods='\n'.join(methods_table), modname=modname)
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return body
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def _make_source(name, init, body):
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""" Combines the code fragments into source code ready to be compiled
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"""
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code = """
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#include <Python.h>
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%(body)s
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PyMODINIT_FUNC
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PyInit_%(name)s(void) {
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%(init)s
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}
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""" % dict(
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name=name, init=init, body=body,
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)
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return code
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def _c_compile(cfile, outputfilename, include_dirs=[], libraries=[],
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library_dirs=[]):
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if sys.platform == 'win32':
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compile_extra = ["/we4013"]
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link_extra = ["/LIBPATH:" + os.path.join(sys.base_prefix, 'libs')]
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elif sys.platform.startswith('linux'):
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compile_extra = [
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"-O0", "-g", "-Werror=implicit-function-declaration", "-fPIC"]
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link_extra = None
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else:
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compile_extra = link_extra = None
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pass
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if sys.platform == 'win32':
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link_extra = link_extra + ['/DEBUG'] # generate .pdb file
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if sys.platform == 'darwin':
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# support Fink & Darwinports
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for s in ('/sw/', '/opt/local/'):
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if (s + 'include' not in include_dirs
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and os.path.exists(s + 'include')):
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include_dirs.append(s + 'include')
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if s + 'lib' not in library_dirs and os.path.exists(s + 'lib'):
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library_dirs.append(s + 'lib')
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outputfilename = outputfilename.with_suffix(get_so_suffix())
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saved_environ = os.environ.copy()
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try:
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build(
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cfile, outputfilename,
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compile_extra, link_extra,
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include_dirs, libraries, library_dirs)
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finally:
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# workaround for a distutils bugs where some env vars can
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# become longer and longer every time it is used
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for key, value in saved_environ.items():
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if os.environ.get(key) != value:
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os.environ[key] = value
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return outputfilename
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def build(cfile, outputfilename, compile_extra, link_extra,
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include_dirs, libraries, library_dirs):
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"cd into the directory where the cfile is, use distutils to build"
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from numpy.distutils.ccompiler import new_compiler
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compiler = new_compiler(force=1, verbose=2)
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compiler.customize('')
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objects = []
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old = os.getcwd()
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os.chdir(cfile.parent)
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try:
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res = compiler.compile(
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[str(cfile.name)],
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include_dirs=include_dirs,
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extra_preargs=compile_extra
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)
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objects += [str(cfile.parent / r) for r in res]
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finally:
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os.chdir(old)
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compiler.link_shared_object(
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objects, str(outputfilename),
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libraries=libraries,
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extra_preargs=link_extra,
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library_dirs=library_dirs)
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def get_so_suffix():
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ret = sysconfig.get_config_var('EXT_SUFFIX')
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assert ret
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return ret
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