1 files changed, 99 insertions, 0 deletions
diff --git a/setuptools/_normalization.py b/setuptools/_normalization.py
new file mode 100644
index 00000000..d6343ca5
--- /dev/null
+++ b/setuptools/_normalization.py
@@ -0,0 +1,99 @@
+import os
+import re
+import sys
+import warnings
+from inspect import cleandoc
+from pathlib import Path
+from typing import Union
+
+from setuptools.extern import packaging
+
+from ._deprecation_warning import SetuptoolsDeprecationWarning
+
+_Path = Union[str, Path]
+
+# https://packaging.python.org/en/latest/specifications/core-metadata/#name
+_VALID_NAME = re.compile(r"^([A-Z0-9]|[A-Z0-9][A-Z0-9._-]*[A-Z0-9])$", re.I)
+_UNSAFE_NAME_CHARS = re.compile(r"[^A-Z0-9.]+", re.I)
+
+
+def path(filename: _Path) -> str:
+    """Normalize a file/dir name for comparison purposes."""
+    # See pkg_resources.normalize_path
+    file = os.path.abspath(filename) if sys.platform == 'cygwin' else filename
+    return os.path.normcase(os.path.realpath(os.path.normpath(file)))
+
+
+def safe_identifier(name: str) -> str:
+    """Make a string safe to be used as Python identifier.
+    >>> safe_identifier("12abc")
+    '_12abc'
+    >>> safe_identifier("__editable__.myns.pkg-78.9.3_local")
+    '__editable___myns_pkg_78_9_3_local'
+    """
+    safe = re.sub(r'\W|^(?=\d)', '_', name)
+    assert safe.isidentifier()
+    return safe
+
+
+def safe_name(component: str) -> str:
+    """Escape a component used as a project name according to Core Metadata.
+    >>> safe_name("hello world")
+    'hello-world'
+    >>> safe_name("hello?world")
+    'hello-world'
+    """
+    # See pkg_resources.safe_name
+    return _UNSAFE_NAME_CHARS.sub("-", component)
+
+
+def safe_version(version: str) -> str:
+    """Convert an arbitrary string into a valid version string.
+    >>> safe_version("1988 12 25")
+    '1988.12.25'
+    >>> safe_version("v0.2.1")
+    '0.2.1'
+    >>> safe_version("v0.2?beta")
+    '0.2b0'
+    >>> safe_version("v0.2 beta")
+    '0.2b0'
+    >>> safe_version("ubuntu lts")
+    Traceback (most recent call last):
+    ...
+    setuptools.extern.packaging.version.InvalidVersion: Invalid version: 'ubuntu.lts'
+    """
+    v = version.replace(' ', '.')
+    try:
+        return str(packaging.version.Version(v))
+    except packaging.version.InvalidVersion:
+        attempt = _UNSAFE_NAME_CHARS.sub("-", v)
+        return str(packaging.version.Version(attempt))
+
+
+def best_effort_version(version: str) -> str:
+    """Convert an arbitrary string into a version-like string.
+    >>> best_effort_version("v0.2 beta")
+    '0.2b0'
+
+    >>> import warnings
+    >>> warnings.simplefilter("ignore", category=SetuptoolsDeprecationWarning)
+    >>> best_effort_version("ubuntu lts")
+    'ubuntu.lts'
+    """
+    try:
+        return safe_version(version)
+    except packaging.version.InvalidVersion:
+        msg = f"""Invalid version: {version!r}.
+        !!\n\n
+        ###################
+        # Invalid version #
+        ###################
+        {version!r} is not valid according to PEP 440.\n
+        Please make sure specify a valid version for your package.
+        Also note that future releases of setuptools may halt the build process
+        if an invalid version is given.
+        \n\n!!
+        """
+        warnings.warn(cleandoc(msg), SetuptoolsDeprecationWarning)
+        v = version.replace(' ', '.')
+        return safe_name(v).strip("_")