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projecten1/lib/python3.6/site-packages/pip/_internal/build_env.py

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+"""Build Environment used for isolation during sdist building
+"""
+
+import os
+from distutils.sysconfig import get_python_lib
+from sysconfig import get_paths
+
+from pip._internal.utils.temp_dir import TempDirectory
+
+
+class BuildEnvironment(object):
+    """Creates and manages an isolated environment to install build deps
+    """
+
+    def __init__(self, no_clean):
+        self._temp_dir = TempDirectory(kind="build-env")
+        self._no_clean = no_clean
+
+    @property
+    def path(self):
+        return self._temp_dir.path
+
+    def __enter__(self):
+        self._temp_dir.create()
+
+        self.save_path = os.environ.get('PATH', None)
+        self.save_pythonpath = os.environ.get('PYTHONPATH', None)
+        self.save_nousersite = os.environ.get('PYTHONNOUSERSITE', None)
+
+        install_scheme = 'nt' if (os.name == 'nt') else 'posix_prefix'
+        install_dirs = get_paths(install_scheme, vars={
+            'base': self.path,
+            'platbase': self.path,
+        })
+
+        scripts = install_dirs['scripts']
+        if self.save_path:
+            os.environ['PATH'] = scripts + os.pathsep + self.save_path
+        else:
+            os.environ['PATH'] = scripts + os.pathsep + os.defpath
+
+        # Note: prefer distutils' sysconfig to get the
+        # library paths so PyPy is correctly supported.
+        purelib = get_python_lib(plat_specific=0, prefix=self.path)
+        platlib = get_python_lib(plat_specific=1, prefix=self.path)
+        if purelib == platlib:
+            lib_dirs = purelib
+        else:
+            lib_dirs = purelib + os.pathsep + platlib
+        if self.save_pythonpath:
+            os.environ['PYTHONPATH'] = lib_dirs + os.pathsep + \
+                self.save_pythonpath
+        else:
+            os.environ['PYTHONPATH'] = lib_dirs
+
+        os.environ['PYTHONNOUSERSITE'] = '1'
+
+        return self.path
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if not self._no_clean:
+            self._temp_dir.cleanup()
+
+        def restore_var(varname, old_value):
+            if old_value is None:
+                os.environ.pop(varname, None)
+            else:
+                os.environ[varname] = old_value
+
+        restore_var('PATH', self.save_path)
+        restore_var('PYTHONPATH', self.save_pythonpath)
+        restore_var('PYTHONNOUSERSITE', self.save_nousersite)
+
+    def cleanup(self):
+        self._temp_dir.cleanup()
+
+
+class NoOpBuildEnvironment(BuildEnvironment):
+    """A no-op drop-in replacement for BuildEnvironment
+    """
+
+    def __init__(self, no_clean):
+        pass
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        pass
+
+    def cleanup(self):
+        pass