[3.7] bpo-26544: Get rid of dependence from distutils in platform. (GH-8356). (GH-8970)

(cherry picked from commit 7d81e8f5)

Lib/platform.py

@@ -136,6 +136,35 @@ except AttributeError:
 # Constant used by test_platform to test linux_distribution().
 _UNIXCONFDIR = '/etc'
 
+# Helper for comparing two version number strings.
+# Based on the description of the PHP's version_compare():
+# http://php.net/manual/en/function.version-compare.php
+
+_ver_stages = {
+    # any string not found in this dict, will get 0 assigned
+    'dev': 10,
+    'alpha': 20, 'a': 20,
+    'beta': 30, 'b': 30,
+    'c': 40,
+    'RC': 50, 'rc': 50,
+    # number, will get 100 assigned
+    'pl': 200, 'p': 200,
+}
+
+_component_re = re.compile(r'([0-9]+|[._+-])')
+
+def _comparable_version(version):
+    result = []
+    for v in _component_re.split(version):
+        if v not in '._+-':
+            try:
+                v = int(v, 10)
+                t = 100
+            except ValueError:
+                t = _ver_stages.get(v, 0)
+            result.extend((t, v))
+    return result
+
 ### Platform specific APIs
 
 _libc_search = re.compile(b'(__libc_init)'
@@ -159,7 +188,7 @@ def libc_ver(executable=sys.executable, lib='', version='', chunksize=16384):
         The file is read and scanned in chunks of chunksize bytes.
 
     """
-    from distutils.version import LooseVersion as V
+    V = _comparable_version
     if hasattr(os.path, 'realpath'):
         # Python 2.2 introduced os.path.realpath(); it is used
         # here to work around problems with Cygwin not being

Lib/test/test_platform.py

@@ -285,6 +285,42 @@ class PlatformTest(unittest.TestCase):
         self.assertEqual(platform.libc_ver(support.TESTFN),
                          ('glibc', '1.23.4'))
 
+    @support.cpython_only
+    def test__comparable_version(self):
+        from platform import _comparable_version as V
+        self.assertEqual(V('1.2.3'), V('1.2.3'))
+        self.assertLess(V('1.2.3'), V('1.2.10'))
+        self.assertEqual(V('1.2.3.4'), V('1_2-3+4'))
+        self.assertLess(V('1.2spam'), V('1.2dev'))
+        self.assertLess(V('1.2dev'), V('1.2alpha'))
+        self.assertLess(V('1.2dev'), V('1.2a'))
+        self.assertLess(V('1.2alpha'), V('1.2beta'))
+        self.assertLess(V('1.2a'), V('1.2b'))
+        self.assertLess(V('1.2beta'), V('1.2c'))
+        self.assertLess(V('1.2b'), V('1.2c'))
+        self.assertLess(V('1.2c'), V('1.2RC'))
+        self.assertLess(V('1.2c'), V('1.2rc'))
+        self.assertLess(V('1.2RC'), V('1.2.0'))
+        self.assertLess(V('1.2rc'), V('1.2.0'))
+        self.assertLess(V('1.2.0'), V('1.2pl'))
+        self.assertLess(V('1.2.0'), V('1.2p'))
+
+        self.assertLess(V('1.5.1'), V('1.5.2b2'))
+        self.assertLess(V('3.10a'), V('161'))
+        self.assertEqual(V('8.02'), V('8.02'))
+        self.assertLess(V('3.4j'), V('1996.07.12'))
+        self.assertLess(V('3.1.1.6'), V('3.2.pl0'))
+        self.assertLess(V('2g6'), V('11g'))
+        self.assertLess(V('0.9'), V('2.2'))
+        self.assertLess(V('1.2'), V('1.2.1'))
+        self.assertLess(V('1.1'), V('1.2.2'))
+        self.assertLess(V('1.1'), V('1.2'))
+        self.assertLess(V('1.2.1'), V('1.2.2'))
+        self.assertLess(V('1.2'), V('1.2.2'))
+        self.assertLess(V('0.4'), V('0.4.0'))
+        self.assertLess(V('1.13++'), V('5.5.kw'))
+        self.assertLess(V('0.960923'), V('2.2beta29'))
+
     def test_parse_release_file(self):
 
         for input, output in (