Work on #476

modules/git/version.go

@@ -11,25 +11,24 @@ import (
 	"github.com/Unknwon/com"
 )
 
+var (
+	// Cached Git version.
+	gitVer *Version
+)
+
 // Version represents version of Git.
 type Version struct {
 	Major, Minor, Patch int
 }
 
-// GetVersion returns current Git version installed.
-func GetVersion() (Version, error) {
-	stdout, stderr, err := com.ExecCmd("git", "version")
-	if err != nil {
-		return Version{}, errors.New(stderr)
-	}
-
-	infos := strings.Split(stdout, " ")
+func ParseVersion(verStr string) (*Version, error) {
+	infos := strings.Split(verStr, ".")
 	if len(infos) < 3 {
-		return Version{}, errors.New("not enough output")
+		return nil, errors.New("incorrect version input")
 	}
 
-	v := Version{}
-	for i, s := range strings.Split(strings.TrimSpace(infos[2]), ".") {
+	v := &Version{}
+	for i, s := range infos {
 		switch i {
 		case 0:
 			v.Major, _ = com.StrTo(s).Int()
@@ -41,3 +40,52 @@ func GetVersion() (Version, error) {
 	}
 	return v, nil
 }
+
+func MustParseVersion(verStr string) *Version {
+	v, _ := ParseVersion(verStr)
+	return v
+}
+
+// Compare compares two versions,
+// it returns 1 if original is greater, 1 if original is smaller, 0 if equal.
+func (v *Version) Compare(that *Version) int {
+	if v.Major > that.Major {
+		return 1
+	} else if v.Major < that.Major {
+		return -1
+	}
+
+	if v.Minor > that.Minor {
+		return 1
+	} else if v.Minor < that.Minor {
+		return -1
+	}
+
+	if v.Patch > that.Patch {
+		return 1
+	} else if v.Patch < that.Patch {
+		return -1
+	}
+
+	return 0
+}
+
+// GetVersion returns current Git version installed.
+func GetVersion() (*Version, error) {
+	if gitVer != nil {
+		return gitVer, nil
+	}
+
+	stdout, stderr, err := com.ExecCmd("git", "version")
+	if err != nil {
+		return nil, errors.New(stderr)
+	}
+
+	infos := strings.Split(stdout, " ")
+	if len(infos) < 3 {
+		return nil, errors.New("not enough output")
+	}
+
+	gitVer, err = ParseVersion(infos[2])
+	return gitVer, err
+}