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version.go
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version.go
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package version
import (
"bufio"
"errors"
"io"
"strings"
"unicode"
)
type parts int
const (
tokenInvalid parts = iota - 1
tokenDigitOrZero
tokenDigit
tokenLetter
tokenSuffix
tokenSuffixNo
tokenRevisionNo
tokenEnd
)
// Version represents a package version
// ref. https://gitlab.alpinelinux.org/alpine/apk-tools/-/blob/master/src/version.c
type Version string
type version bufio.Reader
// NewVersion returns a parsed version
func NewVersion(ver string) (Version, error) {
if !Valid(ver) {
// Even if a version is invalid, a caller needs to be able to do sort.
return Version(ver), errors.New("invalid version")
}
return Version(ver), nil
}
func newVersion(ver string) version {
s := strings.NewReader(ver)
b := bufio.NewReader(s)
return version(*b)
}
func (v1 *version) nextToken(tokenType parts) parts {
n := tokenInvalid
v := (*bufio.Reader)(v1)
r, size, err := v.ReadRune()
if size == 0 && err != nil {
if err != io.EOF {
return tokenInvalid
}
n = tokenEnd
}
if (tokenType == tokenDigit || tokenType == tokenDigitOrZero) && unicode.IsLower(r) {
n = tokenLetter
} else if tokenType == tokenLetter && unicode.IsDigit(r) {
n = tokenDigit
} else if tokenType == tokenSuffix && unicode.IsDigit(r) {
n = tokenSuffixNo
} else {
switch r {
case '.':
n = tokenDigitOrZero
case '_':
n = tokenSuffix
case '-':
r, size, err = v.ReadRune()
if size == 0 && err == io.EOF {
n = tokenInvalid
} else {
n = tokenRevisionNo
}
}
}
if n == tokenEnd || n == tokenLetter || n == tokenDigit || n == tokenSuffixNo {
_ = v.UnreadRune()
}
if n < tokenType {
switch {
case n == tokenDigitOrZero && tokenType == tokenDigit:
return n
case n == tokenSuffix && tokenType == tokenSuffixNo:
return n
case n == tokenDigit && tokenType == tokenLetter:
return n
default:
return tokenInvalid
}
}
return n
}
var (
preSuffixes = [4]string{"alpha", "beta", "pre", "rc"}
postSuffixes = [5]string{"cvs", "svn", "git", "hg", "p"}
)
func (v1 *version) getToken(tokenType parts) (int, parts, error) {
nt := tokenInvalid
var value int
v := (*bufio.Reader)(v1)
r, size, err := v.ReadRune()
if size == 0 && err != nil && err != io.EOF {
return 0, tokenType, err
}
switch tokenType {
case tokenDigitOrZero:
/* Leading zero digits get a special treatment */
if r == '0' {
for {
value -= 1
r, size, err := v.ReadRune()
if err != nil && err != io.EOF {
return 0, tokenType, err
}
if size == 0 && err == io.EOF {
break
}
if r != '0' {
_ = v.UnreadRune()
break
}
}
nt = tokenDigit
break
}
fallthrough
case tokenDigit, tokenSuffixNo, tokenRevisionNo:
for unicode.IsDigit(r) {
value *= 10
value += int(r - '0')
r, size, err = v.ReadRune()
if err != nil && err != io.EOF {
return 0, tokenType, err
}
if size == 0 && err == io.EOF {
break
}
}
_ = v.UnreadRune()
case tokenLetter:
value = int(r)
case tokenSuffix:
_ = v.UnreadRune()
for i, s := range preSuffixes {
b, err := v.Peek(len(s))
if err != nil && err != io.EOF {
return 0, tokenType, err
}
if string(b) == s {
value = i - len(preSuffixes)
_, _ = v.Discard(len(s))
break
}
}
if value != 0 {
break
}
value = -1
for i, s := range postSuffixes {
b, err := v.Peek(len(s))
if err != nil && err != io.EOF {
return 0, tokenType, err
}
if string(b) == s {
value = i
_, _ = v.Discard(len(s))
break
}
}
if value >= 0 {
break
}
/* fallthrough: invalid suffix */
fallthrough
default:
tokenType = tokenInvalid
return -1, tokenType, nil
}
if _, err = v.Peek(1); err == io.EOF {
tokenType = tokenEnd
} else if nt != tokenInvalid {
tokenType = nt
} else {
tokenType = v1.nextToken(tokenType)
}
return value, tokenType, nil
}
const (
apkVersionEqual = 0
apkVersionLess = -1
apkVersionGreater = 1
)
// Valid validates the version
func Valid(ver string) bool {
t := tokenDigit
v := newVersion(ver)
for t != tokenEnd && t != tokenInvalid {
_, t, _ = v.getToken(t)
}
return t == tokenEnd
}
// Equal returns whether this version is equal with another version.
func (v1 *Version) Equal(v2 Version) bool {
return v1.Compare(v2) == 0
}
// GreaterThan returns whether this version is greater than another version.
func (v1 *Version) GreaterThan(v2 Version) bool {
return v1.Compare(v2) > 0
}
// LessThan returns whether this version is less than another version.
func (v1 Version) LessThan(v2 Version) bool {
return v1.Compare(v2) < 0
}
// Compare returns an integer comparing two version according to apk version.
// The result will be 0 if v1==v2, -1 if v1 < v2, and +1 if v1 > v2.
func (v1 Version) Compare(v2 Version) int {
return compare(v1, v2)
}
func compare(ver1, ver2 Version) int {
v1 := newVersion(string(ver1))
v2 := newVersion(string(ver2))
at := tokenDigit
bt := tokenDigit
var av, bv int
for at == bt && at != tokenEnd && at != tokenInvalid && av == bv {
// err is not supposed to happen
av, at, _ = v1.getToken(at)
bv, bt, _ = v2.getToken(bt)
}
/* value of this token differs? */
if av < bv {
return apkVersionLess
} else if av > bv {
return apkVersionGreater
}
/* both have TOKEN_END or TOKEN_INVALID next? */
if at == bt {
return apkVersionEqual
}
/* leading version components and their values are equal,
* now the non-terminating version is greater unless it's a suffix
* indicating pre-release */
if at == tokenSuffix {
v, _, _ := v1.getToken(at)
if v < 0 {
return apkVersionLess
}
}
if bt == tokenSuffix {
v, _, err := v2.getToken(bt)
if err != nil {
return 0
}
if v < 0 {
return apkVersionGreater
}
}
if at > bt {
return apkVersionLess
} else if at < bt {
return apkVersionGreater
}
return apkVersionEqual
}