A simple version implementation in in Go.

version.go

package version

import (
	"strconv"
	"strings"
)

type Version struct {
	Major int
	Minor int
	Patch int
}

func parseVersion(s string) *Version {
	strs := strings.SplitN(s, ".", 3)
	major, minor, patch := "", "", ""

	switch len(strs) {
	case 1:
		major = strs[0]
	case 2:
		major, minor = strs[0], strs[1]
	case 3:
		major, minor, patch = strs[0], strs[1], strs[2]
	}

	v := Version{
		Major: SafeParseInt(major),
		Minor: SafeParseInt(minor),
		Patch: SafeParseInt(patch),
	}
	return &v
}

func ParseVersion(s string) (v *Version) {
	return parseVersion(s)
}

// Cmp compares the version represented by v1 and v2 and returns:
//
//     -1 if v1 <  v2
//      0 if v1 == v2
//     +1 if v1 >  v2
//
func (v1 *Version) Cmp(v2 *Version) int {
	return v1.compare(v2)
}

// GreaterThan returns true when v1 > v2.
func (v1 *Version) GreaterThan(v2 *Version) bool {
	return v1.compare(v2) > 0
}

// GreaterThanOrEqual returns true when v1 >= v2.
func (v1 *Version) GreaterThanOrEqual(v2 *Version) bool {
	return v1.compare(v2) >= 0
}

// Equal returns true when v1 == v2.
func (v1 *Version) Equal(v2 *Version) bool {
	return v1.compare(v2) == 0
}

// LessThanOrEqual returns true when v1 <= v2.
func (v1 *Version) LessThanOrEqual(v2 *Version) bool {
	return v1.compare(v2) <= 0
}

// LessThan returns true when v1 < v2.
func (v1 *Version) LessThan(v2 *Version) bool {
	return v1.compare(v2) < 0
}

func (v1 *Version) compare(v2 *Version) int {
	switch {
	case v1.Major > v2.Major:
		return 1
	case v1.Major < v2.Major:
		return -1
	}

	switch {
	case v1.Minor > v2.Minor:
		return 1
	case v1.Minor < v2.Minor:
		return -1
	}

	switch {
	case v1.Patch > v2.Patch:
		return 1
	case v1.Patch < v2.Patch:
		return -1
	}

	return 0
}

// SafeParseInt interprets a string s as int safely, i.e., ignore any parse error.
func SafeParseInt(s string) (i int) {
	i, _ = strconv.Atoi(s)
	return
}