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semver.go
178 lines (138 loc) · 3.24 KB
/
semver.go
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package semver
import (
"bytes"
"errors"
"fmt"
"strconv"
"strings"
)
type Version struct {
Major int64
Minor int64
Patch int64
PreRelease PreRelease
Metadata string
}
type PreRelease string
func splitOff(input *string, delim string) (val string) {
parts := strings.SplitN(*input, delim, 2)
if len(parts) == 2 {
*input = parts[0]
val = parts[1]
}
return val
}
func NewVersion(version string) (*Version, error) {
v := Version{}
dotParts := strings.SplitN(version, ".", 3)
if len(dotParts) != 3 {
return nil, errors.New(fmt.Sprintf("%s is not in dotted-tri format", version))
}
v.Metadata = splitOff(&dotParts[2], "+")
v.PreRelease = PreRelease(splitOff(&dotParts[2], "-"))
parsed := make([]int64, 3, 3)
for i, v := range dotParts[:3] {
val, err := strconv.ParseInt(v, 10, 64)
parsed[i] = val
if err != nil {
return nil, err
}
}
v.Major = parsed[0]
v.Minor = parsed[1]
v.Patch = parsed[2]
return &v, nil
}
func (v *Version) String() string {
var buffer bytes.Buffer
base := fmt.Sprintf("%d.%d.%d", v.Major, v.Minor, v.Patch)
buffer.WriteString(base)
if v.PreRelease != "" {
buffer.WriteString(fmt.Sprintf("-%s", v.PreRelease))
}
if v.Metadata != "" {
buffer.WriteString(fmt.Sprintf("+%s", v.Metadata))
}
return buffer.String()
}
func (v *Version) LessThan(versionB Version) bool {
versionA := *v
cmp := recursiveCompare(versionA.Slice(), versionB.Slice())
if cmp == 0 {
cmp = preReleaseCompare(versionA, versionB)
}
if cmp == -1 {
return true
}
return false
}
/* Slice converts the comparable parts of the semver into a slice of strings */
func (v *Version) Slice() []int64 {
return []int64{v.Major, v.Minor, v.Patch}
}
func (p *PreRelease) Slice() []string {
preRelease := string(*p)
return strings.Split(preRelease, ".")
}
func preReleaseCompare(versionA Version, versionB Version) int {
a := versionA.PreRelease
b := versionB.PreRelease
/* Handle the case where if two versions are otherwise equal it is the
* one without a PreRelease that is greater */
if len(a) == 0 && (len(b) > 0) {
return 1
} else if len(b) == 0 && (len(a) > 0) {
return -1
}
// If there is a prelease, check and compare each part.
return recursivePreReleaseCompare(a.Slice(), b.Slice())
}
func recursiveCompare(versionA []int64, versionB []int64) int {
if len(versionA) == 0 {
return 0
}
a := versionA[0]
b := versionB[0]
if a > b {
return 1
} else if a < b {
return -1
}
return recursiveCompare(versionA[1:], versionB[1:])
}
func recursivePreReleaseCompare(versionA []string, versionB []string) int {
// Handle slice length disparity.
if len(versionA) == 0 {
// Nothing to compare too, so we return 0
return 0
} else if len(versionB) == 0 {
// We're longer than versionB so return 1.
return 1
}
a := versionA[0]
b := versionB[0]
aInt := false; bInt := false
aI, err := strconv.Atoi(versionA[0])
if err == nil {
aInt = true
}
bI, err := strconv.Atoi(versionB[0])
if err == nil {
bInt = true
}
// Handle Integer Comparison
if aInt && bInt {
if aI > bI {
return 1
} else if aI < bI {
return -1
}
}
// Handle String Comparison
if a > b {
return 1
} else if a < b {
return -1
}
return recursivePreReleaseCompare(versionA[1:], versionB[1:])
}