Add alpine support in univers

Currently univers don't have a VersionClass for alpine linux, so add a version class for alpine linux and use same vercmp method that has been used by gentoo, avoid cases for now  which have a leading 0 in them.

Verify the current implementation of vercmp with the test data from here https://git.alpinelinux.org/apk-tools/tree/tests/version.data add ABOUT file and license for same

Signed-off-by: Tushar Goel <tushar.goel.dav@gmail.com>

Author: TG1999

src/univers/rpm.py

@@ -131,9 +131,9 @@ def compare_rpm_versions(a: Union[RpmVersion, str], b: Union[RpmVersion, str]) -
 
 
 class Vercmp:
-    R_NONALNUMTILDE_CARET = re.compile(br"^([^a-zA-Z0-9~\^]*)(.*)$")
-    R_NUM = re.compile(br"^([\d]+)(.*)$")
-    R_ALPHA = re.compile(br"^([a-zA-Z]+)(.*)$")
+    R_NONALNUMTILDE_CARET = re.compile(rb"^([^a-zA-Z0-9~\^]*)(.*)$")
+    R_NUM = re.compile(rb"^([\d]+)(.*)$")
+    R_ALPHA = re.compile(rb"^([a-zA-Z]+)(.*)$")
 
     @classmethod
     def compare(cls, first, second):

src/univers/version_range.py

@@ -721,6 +721,11 @@ class EbuildVersionRange(VersionRange):
     version_class = versions.GentooVersion
 
 
+class AlpineLinuxVersionRange(VersionRange):
+    scheme = "alpinelinux"
+    version_class = versions.AlpineLinuxVersion
+
+
 class ArchLinuxVersionRange(VersionRange):
     scheme = "archlinux"
     version_class = versions.ArchLinuxVersion

src/univers/versions.py

@@ -34,6 +34,21 @@ class InvalidVersion(ValueError):
     pass
 
 
+def valid_alpine_version(s):
+    """
+    Return True is the string `s` is a valid Alpine version.
+    We do not support yet version strings that start with
+    non-significant zeros.
+    """
+    left, _, _ = s.partition(".")
+    # hanlde the suffice case
+    left, _, _ = left.partition("-")
+    if not left.isdigit():
+        return True
+    i = int(left)
+    return str(i) == left
+
+
 @attr.s(frozen=True, order=False, hash=True)
 class Version:
     """
@@ -299,3 +314,25 @@ def __lt__(self, other):
         if not isinstance(other, self.__class__):
             return NotImplemented
         return gentoo.vercmp(self.value, other.value) == -1
+
+
+@attr.s(frozen=True, order=False, eq=False, hash=True)
+class AlpineLinuxVersion(Version):
+    @classmethod
+    def is_valid(cls, string):
+        return valid_alpine_version(string) and gentoo.is_valid(string)
+
+    def __eq__(self, other):
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return gentoo.vercmp(self.value, other.value) == 0
+
+    def __lt__(self, other):
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return gentoo.vercmp(self.value, other.value) < 0
+
+    def __gt__(self, other):
+        if not isinstance(other, self.__class__):
+            return NotImplemented
+        return gentoo.vercmp(self.value, other.value) > 0