refactor: improve cran version parser

pkg/semantic/version-cran.go

@@ -5,6 +5,13 @@ import (
 	"strings"
 )
 
+// CRANVersion is the representation of a version of a package that is held
+// in the CRAN ecosystem (https://cran.r-project.org/).
+//
+// A version is a sequence of at least two non-negative integers separated by
+// either a period or a dash.
+//
+// See https://astrostatistics.psu.edu/su07/R/html/base/html/package_version.html
 type CRANVersion struct {
 	components Components
 }
@@ -14,6 +21,8 @@ func (v CRANVersion) Compare(w CRANVersion) int {
 		return diff
 	}
 
+	// versions are only equal if they also have the same number of components,
+	// otherwise the longer one is considered greater
 	if len(v.components) == len(w.components) {
 		return 0
 	}
@@ -30,13 +39,12 @@ func (v CRANVersion) CompareStr(str string) int {
 }
 
 func parseCRANVersion(str string) CRANVersion {
-	str = strings.ReplaceAll(str, "-", ".")
+	// dashes and periods have the same weight, so we can just normalize to periods
+	parts := strings.Split(strings.ReplaceAll(str, "-", "."), ".")
 
-	splitted := strings.Split(str, ".")
+	components := make(Components, 0, len(parts))
 
-	components := make(Components, 0, len(splitted))
-
-	for _, s := range splitted {
+	for _, s := range parts {
 		v, _ := new(big.Int).SetString(s, 10)
 
 		components = append(components, v)