Custom Version implementation

Author: tony

src/libtmux/_compat.py

@@ -1,4 +1,5 @@
 # flake8: NOQA
+import functools
 import sys
 import types
 import typing as t
@@ -31,3 +32,105 @@ def str_from_console(s: t.Union[str, bytes]) -> str:
         return str(s)
     except UnicodeDecodeError:
         return str(s, encoding="utf_8") if isinstance(s, bytes) else s
+
+
+try:
+    import re
+    from typing import Iterator, List, Tuple
+
+    from packaging.version import Version
+
+    ###
+    ### Legacy support for LooseVersion / LegacyVersion, e.g. 2.4-openbsd
+    ### https://github.com/pypa/packaging/blob/21.3/packaging/version.py#L106-L115
+    ### License: BSD, Accessed: Jan 14th, 2022
+    ###
+
+    LegacyCmpKey = Tuple[int, Tuple[str, ...]]
+
+    _legacy_version_component_re = re.compile(r"(\d+ | [a-z]+ | \.| -)", re.VERBOSE)
+    _legacy_version_replacement_map = {
+        "pre": "c",
+        "preview": "c",
+        "-": "final-",
+        "rc": "c",
+        "dev": "@",
+    }
+
+    def _parse_version_parts(s: str) -> Iterator[str]:
+        for part in _legacy_version_component_re.split(s):
+            part = _legacy_version_replacement_map.get(part, part)
+
+            if not part or part == ".":
+                continue
+
+            if part[:1] in "0123456789":
+                # pad for numeric comparison
+                yield part.zfill(8)
+            else:
+                yield "*" + part
+
+        # ensure that alpha/beta/candidate are before final
+        yield "*final"
+
+    def _legacy_cmpkey(version: str) -> LegacyCmpKey:
+        # We hardcode an epoch of -1 here. A PEP 440 version can only have a epoch
+        # greater than or equal to 0. This will effectively put the LegacyVersion,
+        # which uses the defacto standard originally implemented by setuptools,
+        # as before all PEP 440 versions.
+        epoch = -1
+
+        # This scheme is taken from pkg_resources.parse_version setuptools prior to
+        # it's adoption of the packaging library.
+        parts: List[str] = []
+        for part in _parse_version_parts(version.lower()):
+            if part.startswith("*"):
+                # remove "-" before a prerelease tag
+                if part < "*final":
+                    while parts and parts[-1] == "*final-":
+                        parts.pop()
+
+                # remove trailing zeros from each series of numeric parts
+                while parts and parts[-1] == "00000000":
+                    parts.pop()
+
+            parts.append(part)
+
+        return epoch, tuple(parts)
+
+    @functools.total_ordering
+    class LegacyVersion:
+        _key = None  # type: Union[CmpKey, LegacyCmpKey]
+
+        def __hash__(self) -> int:
+            return hash(self._key)
+
+        def __init__(self, version: str) -> None:
+            self._version = str(version)
+            self._key = _legacy_cmpkey(self._version)
+
+        def __str__(self) -> str:
+            return self._version
+
+        def __lt__(self, other):
+            if isinstance(other, str):
+                other = LegacyVersion(other)
+            if not isinstance(other, LegacyVersion):
+                return NotImplemented
+
+            return self._key < other._key
+
+        def __eq__(self, other) -> bool:
+            if isinstance(other, str):
+                other = LegacyVersion(other)
+            if not isinstance(other, LegacyVersion):
+                return NotImplemented
+
+            return self._key == other._key
+
+        def __repr__(self) -> str:
+            return "<LegacyVersion({0})>".format(repr(str(self)))
+
+    LooseVersion = LegacyVersion
+except ImportError:
+    from distutils.version import LooseVersion, Version

tests/test_version.py

@@ -0,0 +1,43 @@
+import operator
+from contextlib import nullcontext as does_not_raise
+
+import pytest
+
+from libtmux._compat import LooseVersion
+
+
+@pytest.mark.parametrize(
+    "version",
+    [
+        "1",
+        "1.0",
+        "1.0.0",
+        "1.0.0b",
+        "1.0.0b1",
+        "1.0.0b-openbsd",
+        "1.0.0-next",
+        "1.0.0-next.1",
+    ],
+)
+def test_version(version):
+    assert LooseVersion(version)
+
+
+@pytest.mark.parametrize(
+    "version,op,versionb,raises",
+    [
+        ["1", operator.eq, "1", False],
+        ["1", operator.eq, "1.0", False],
+        ["1", operator.eq, "1.0.0", False],
+        ["1", operator.gt, "1.0.0a", False],
+        ["1", operator.gt, "1.0.0b", False],
+        ["1", operator.lt, "1.0.0p1", False],
+        ["1", operator.lt, "1.0.0-openbsd", False],
+        ["1", operator.lt, "1", AssertionError],
+        ["1", operator.lt, "1", AssertionError],
+    ],
+)
+def test_version_compare(version, op, versionb, raises):
+    raises_ctx = pytest.raises(raises) if raises else does_not_raise()
+    with raises_ctx:
+        assert op(LooseVersion(version), LooseVersion(versionb))