Merge pull request #1509 from thunder-coding/dpkg-compliant-version-compare

make version comparision more similar to that of dpkg

Author: neolynx

AUTHORS

@@ -74,5 +74,6 @@ List of contributors, in chronological order:
 * JupiterRider (https://github.com/JupiterRider)
 * Agustin Henze (https://github.com/agustinhenze)
 * Tobias Assarsson (https://github.com/daedaluz)
+* Yaksh Bariya (https://github.com/thunder-coding)
 * Juan Calderon-Perez (https://github.com/gaby)
 * Ato Araki (https://github.com/atotto)

deb/version.go

@@ -30,14 +30,14 @@ func CompareVersions(ver1, ver2 string) int {
 
 // parseVersions breaks down full version to components (possibly empty)
 func parseVersion(ver string) (epoch, upstream, debian string) {
-	i := strings.LastIndex(ver, "-")
+	i := strings.Index(ver, ":")
 	if i != -1 {
-		debian, ver = ver[i+1:], ver[:i]
+		epoch, ver = ver[:i], ver[i+1:]
 	}
 
-	i = strings.Index(ver, ":")
+	i = strings.Index(ver, "-")
 	if i != -1 {
-		epoch, ver = ver[:i], ver[i+1:]
+		debian, ver = ver[i+1:], ver[:i]
 	}
 
 	upstream = ver

deb/version_test.go

@@ -20,10 +20,10 @@ func (s *VersionSuite) TestParseVersion(c *C) {
 	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3.4", "1"})
 
 	e, u, d = parseVersion("1.3-pre4-1")
-	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3-pre4", "1"})
+	c.Check([]string{e, u, d}, DeepEquals, []string{"", "1.3", "pre4-1"})
 
 	e, u, d = parseVersion("4:1.3-pre4-1")
-	c.Check([]string{e, u, d}, DeepEquals, []string{"4", "1.3-pre4", "1"})
+	c.Check([]string{e, u, d}, DeepEquals, []string{"4", "1.3", "pre4-1"})
 }
 
 func (s *VersionSuite) TestCompareLexicographic(c *C) {
@@ -100,6 +100,7 @@ func (s *VersionSuite) TestCompareVersions(c *C) {
 	c.Check(CompareVersions("1.0-133-avc", "1.0"), Equals, 1)
 
 	c.Check(CompareVersions("5.2.0.3", "5.2.0.283"), Equals, -1)
+	c.Check(CompareVersions("4.3.5a", "4.3.5-rc3-1"), Equals, 1)
 }
 
 func (s *VersionSuite) TestParseDependency(c *C) {