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semver.go
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semver.go
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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package semver implements comparison of semantic version strings.
// In this package, semantic version strings must begin with a leading "v",
// as in "v1.0.0".
//
// The general form of a semantic version string accepted by this package is
//
// vMAJOR[.MINOR[.PATCH[-PRERELEASE][+BUILD]]]
//
// where square brackets indicate optional parts of the syntax;
// MAJOR, MINOR, and PATCH are decimal integers without extra leading zeros;
// PRERELEASE and BUILD are each a series of non-empty dot-separated identifiers
// using only alphanumeric characters and hyphens; and
// all-numeric PRERELEASE identifiers must not have leading zeros.
//
// This package follows Semantic Versioning 2.0.0 (see semver.org)
// with two exceptions. First, it requires the "v" prefix. Second, it recognizes
// vMAJOR and vMAJOR.MINOR (with no prerelease or build suffixes)
// as shorthands for vMAJOR.0.0 and vMAJOR.MINOR.0.
// Package writefreely
// copied from
// https://github.com/golang/tools/blob/master/internal/semver/semver.go
// slight modifications made
package writefreely
// parsed returns the parsed form of a semantic version string.
type parsed struct {
major string
minor string
patch string
short string
prerelease string
build string
err string
}
// IsValid reports whether v is a valid semantic version string.
func IsValid(v string) bool {
_, ok := semParse(v)
return ok
}
// CompareSemver returns an integer comparing two versions according to
// according to semantic version precedence.
// The result will be 0 if v == w, -1 if v < w, or +1 if v > w.
//
// An invalid semantic version string is considered less than a valid one.
// All invalid semantic version strings compare equal to each other.
func CompareSemver(v, w string) int {
pv, ok1 := semParse(v)
pw, ok2 := semParse(w)
if !ok1 && !ok2 {
return 0
}
if !ok1 {
return -1
}
if !ok2 {
return +1
}
if c := compareInt(pv.major, pw.major); c != 0 {
return c
}
if c := compareInt(pv.minor, pw.minor); c != 0 {
return c
}
if c := compareInt(pv.patch, pw.patch); c != 0 {
return c
}
return comparePrerelease(pv.prerelease, pw.prerelease)
}
func semParse(v string) (p parsed, ok bool) {
if v == "" || v[0] != 'v' {
p.err = "missing v prefix"
return
}
p.major, v, ok = parseInt(v[1:])
if !ok {
p.err = "bad major version"
return
}
if v == "" {
p.minor = "0"
p.patch = "0"
p.short = ".0.0"
return
}
if v[0] != '.' {
p.err = "bad minor prefix"
ok = false
return
}
p.minor, v, ok = parseInt(v[1:])
if !ok {
p.err = "bad minor version"
return
}
if v == "" {
p.patch = "0"
p.short = ".0"
return
}
if v[0] != '.' {
p.err = "bad patch prefix"
ok = false
return
}
p.patch, v, ok = parseInt(v[1:])
if !ok {
p.err = "bad patch version"
return
}
if len(v) > 0 && v[0] == '-' {
p.prerelease, v, ok = parsePrerelease(v)
if !ok {
p.err = "bad prerelease"
return
}
}
if len(v) > 0 && v[0] == '+' {
p.build, v, ok = parseBuild(v)
if !ok {
p.err = "bad build"
return
}
}
if v != "" {
p.err = "junk on end"
ok = false
return
}
ok = true
return
}
func parseInt(v string) (t, rest string, ok bool) {
if v == "" {
return
}
if v[0] < '0' || '9' < v[0] {
return
}
i := 1
for i < len(v) && '0' <= v[i] && v[i] <= '9' {
i++
}
if v[0] == '0' && i != 1 {
return
}
return v[:i], v[i:], true
}
func parsePrerelease(v string) (t, rest string, ok bool) {
// "A pre-release version MAY be denoted by appending a hyphen and
// a series of dot separated identifiers immediately following the patch version.
// Identifiers MUST comprise only ASCII alphanumerics and hyphen [0-9A-Za-z-].
// Identifiers MUST NOT be empty. Numeric identifiers MUST NOT include leading zeroes."
if v == "" || v[0] != '-' {
return
}
i := 1
start := 1
for i < len(v) && v[i] != '+' {
if !isIdentChar(v[i]) && v[i] != '.' {
return
}
if v[i] == '.' {
if start == i || isBadNum(v[start:i]) {
return
}
start = i + 1
}
i++
}
if start == i || isBadNum(v[start:i]) {
return
}
return v[:i], v[i:], true
}
func parseBuild(v string) (t, rest string, ok bool) {
if v == "" || v[0] != '+' {
return
}
i := 1
start := 1
for i < len(v) {
if !isIdentChar(v[i]) {
return
}
if v[i] == '.' {
if start == i {
return
}
start = i + 1
}
i++
}
if start == i {
return
}
return v[:i], v[i:], true
}
func isIdentChar(c byte) bool {
return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '-'
}
func isBadNum(v string) bool {
i := 0
for i < len(v) && '0' <= v[i] && v[i] <= '9' {
i++
}
return i == len(v) && i > 1 && v[0] == '0'
}
func isNum(v string) bool {
i := 0
for i < len(v) && '0' <= v[i] && v[i] <= '9' {
i++
}
return i == len(v)
}
func compareInt(x, y string) int {
if x == y {
return 0
}
if len(x) < len(y) {
return -1
}
if len(x) > len(y) {
return +1
}
if x < y {
return -1
} else {
return +1
}
}
func comparePrerelease(x, y string) int {
// "When major, minor, and patch are equal, a pre-release version has
// lower precedence than a normal version.
// Example: 1.0.0-alpha < 1.0.0.
// Precedence for two pre-release versions with the same major, minor,
// and patch version MUST be determined by comparing each dot separated
// identifier from left to right until a difference is found as follows:
// identifiers consisting of only digits are compared numerically and
// identifiers with letters or hyphens are compared lexically in ASCII
// sort order. Numeric identifiers always have lower precedence than
// non-numeric identifiers. A larger set of pre-release fields has a
// higher precedence than a smaller set, if all of the preceding
// identifiers are equal.
// Example: 1.0.0-alpha < 1.0.0-alpha.1 < 1.0.0-alpha.beta <
// 1.0.0-beta < 1.0.0-beta.2 < 1.0.0-beta.11 < 1.0.0-rc.1 < 1.0.0."
if x == y {
return 0
}
if x == "" {
return +1
}
if y == "" {
return -1
}
for x != "" && y != "" {
x = x[1:] // skip - or .
y = y[1:] // skip - or .
var dx, dy string
dx, x = nextIdent(x)
dy, y = nextIdent(y)
if dx != dy {
ix := isNum(dx)
iy := isNum(dy)
if ix != iy {
if ix {
return -1
} else {
return +1
}
}
if ix {
if len(dx) < len(dy) {
return -1
}
if len(dx) > len(dy) {
return +1
}
}
if dx < dy {
return -1
} else {
return +1
}
}
}
if x == "" {
return -1
} else {
return +1
}
}
func nextIdent(x string) (dx, rest string) {
i := 0
for i < len(x) && x[i] != '.' {
i++
}
return x[:i], x[i:]
}

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