389 lines
8.5 KiB
Go
389 lines
8.5 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package semver implements comparison of semantic version strings.
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// In this package, semantic version strings must begin with a leading "v",
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// as in "v1.0.0".
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//
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// The general form of a semantic version string accepted by this package is
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//
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// vMAJOR[.MINOR[.PATCH[-PRERELEASE][+BUILD]]]
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//
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// where square brackets indicate optional parts of the syntax;
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// MAJOR, MINOR, and PATCH are decimal integers without extra leading zeros;
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// PRERELEASE and BUILD are each a series of non-empty dot-separated identifiers
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// using only alphanumeric characters and hyphens; and
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// all-numeric PRERELEASE identifiers must not have leading zeros.
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//
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// This package follows Semantic Versioning 2.0.0 (see semver.org)
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// with two exceptions. First, it requires the "v" prefix. Second, it recognizes
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// vMAJOR and vMAJOR.MINOR (with no prerelease or build suffixes)
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// as shorthands for vMAJOR.0.0 and vMAJOR.MINOR.0.
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package semver
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// parsed returns the parsed form of a semantic version string.
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type parsed struct {
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major string
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minor string
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patch string
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short string
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prerelease string
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build string
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err string
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}
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// IsValid reports whether v is a valid semantic version string.
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func IsValid(v string) bool {
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_, ok := parse(v)
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return ok
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}
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// Canonical returns the canonical formatting of the semantic version v.
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// It fills in any missing .MINOR or .PATCH and discards build metadata.
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// Two semantic versions compare equal only if their canonical formattings
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// are identical strings.
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// The canonical invalid semantic version is the empty string.
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func Canonical(v string) string {
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p, ok := parse(v)
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if !ok {
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return ""
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}
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if p.build != "" {
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return v[:len(v)-len(p.build)]
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}
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if p.short != "" {
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return v + p.short
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}
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return v
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}
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// Major returns the major version prefix of the semantic version v.
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// For example, Major("v2.1.0") == "v2".
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// If v is an invalid semantic version string, Major returns the empty string.
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func Major(v string) string {
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pv, ok := parse(v)
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if !ok {
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return ""
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}
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return v[:1+len(pv.major)]
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}
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// MajorMinor returns the major.minor version prefix of the semantic version v.
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// For example, MajorMinor("v2.1.0") == "v2.1".
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// If v is an invalid semantic version string, MajorMinor returns the empty string.
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func MajorMinor(v string) string {
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pv, ok := parse(v)
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if !ok {
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return ""
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}
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i := 1 + len(pv.major)
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if j := i + 1 + len(pv.minor); j <= len(v) && v[i] == '.' && v[i+1:j] == pv.minor {
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return v[:j]
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}
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return v[:i] + "." + pv.minor
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}
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// Prerelease returns the prerelease suffix of the semantic version v.
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// For example, Prerelease("v2.1.0-pre+meta") == "-pre".
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// If v is an invalid semantic version string, Prerelease returns the empty string.
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func Prerelease(v string) string {
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pv, ok := parse(v)
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if !ok {
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return ""
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}
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return pv.prerelease
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}
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// Build returns the build suffix of the semantic version v.
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// For example, Build("v2.1.0+meta") == "+meta".
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// If v is an invalid semantic version string, Build returns the empty string.
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func Build(v string) string {
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pv, ok := parse(v)
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if !ok {
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return ""
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}
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return pv.build
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}
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// Compare returns an integer comparing two versions according to
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// according to semantic version precedence.
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// The result will be 0 if v == w, -1 if v < w, or +1 if v > w.
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//
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// An invalid semantic version string is considered less than a valid one.
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// All invalid semantic version strings compare equal to each other.
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func Compare(v, w string) int {
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pv, ok1 := parse(v)
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pw, ok2 := parse(w)
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if !ok1 && !ok2 {
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return 0
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}
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if !ok1 {
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return -1
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}
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if !ok2 {
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return +1
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}
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if c := compareInt(pv.major, pw.major); c != 0 {
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return c
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}
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if c := compareInt(pv.minor, pw.minor); c != 0 {
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return c
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}
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if c := compareInt(pv.patch, pw.patch); c != 0 {
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return c
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}
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return comparePrerelease(pv.prerelease, pw.prerelease)
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}
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// Max canonicalizes its arguments and then returns the version string
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// that compares greater.
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func Max(v, w string) string {
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v = Canonical(v)
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w = Canonical(w)
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if Compare(v, w) > 0 {
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return v
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}
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return w
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}
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func parse(v string) (p parsed, ok bool) {
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if v == "" || v[0] != 'v' {
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p.err = "missing v prefix"
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return
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}
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p.major, v, ok = parseInt(v[1:])
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if !ok {
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p.err = "bad major version"
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return
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}
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if v == "" {
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p.minor = "0"
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p.patch = "0"
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p.short = ".0.0"
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return
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}
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if v[0] != '.' {
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p.err = "bad minor prefix"
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ok = false
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return
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}
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p.minor, v, ok = parseInt(v[1:])
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if !ok {
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p.err = "bad minor version"
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return
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}
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if v == "" {
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p.patch = "0"
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p.short = ".0"
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return
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}
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if v[0] != '.' {
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p.err = "bad patch prefix"
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ok = false
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return
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}
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p.patch, v, ok = parseInt(v[1:])
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if !ok {
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p.err = "bad patch version"
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return
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}
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if len(v) > 0 && v[0] == '-' {
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p.prerelease, v, ok = parsePrerelease(v)
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if !ok {
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p.err = "bad prerelease"
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return
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}
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}
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if len(v) > 0 && v[0] == '+' {
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p.build, v, ok = parseBuild(v)
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if !ok {
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p.err = "bad build"
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return
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}
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}
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if v != "" {
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p.err = "junk on end"
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ok = false
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return
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}
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ok = true
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return
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}
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func parseInt(v string) (t, rest string, ok bool) {
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if v == "" {
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return
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}
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if v[0] < '0' || '9' < v[0] {
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return
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}
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i := 1
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for i < len(v) && '0' <= v[i] && v[i] <= '9' {
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i++
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}
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if v[0] == '0' && i != 1 {
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return
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}
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return v[:i], v[i:], true
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}
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func parsePrerelease(v string) (t, rest string, ok bool) {
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// "A pre-release version MAY be denoted by appending a hyphen and
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// a series of dot separated identifiers immediately following the patch version.
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// Identifiers MUST comprise only ASCII alphanumerics and hyphen [0-9A-Za-z-].
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// Identifiers MUST NOT be empty. Numeric identifiers MUST NOT include leading zeroes."
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if v == "" || v[0] != '-' {
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return
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}
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i := 1
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start := 1
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for i < len(v) && v[i] != '+' {
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if !isIdentChar(v[i]) && v[i] != '.' {
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return
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}
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if v[i] == '.' {
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if start == i || isBadNum(v[start:i]) {
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return
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}
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start = i + 1
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}
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i++
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}
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if start == i || isBadNum(v[start:i]) {
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return
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}
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return v[:i], v[i:], true
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}
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func parseBuild(v string) (t, rest string, ok bool) {
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if v == "" || v[0] != '+' {
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return
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}
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i := 1
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start := 1
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for i < len(v) {
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if !isIdentChar(v[i]) {
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return
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}
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if v[i] == '.' {
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if start == i {
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return
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}
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start = i + 1
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}
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i++
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}
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if start == i {
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return
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}
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return v[:i], v[i:], true
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}
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func isIdentChar(c byte) bool {
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return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '-'
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}
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func isBadNum(v string) bool {
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i := 0
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for i < len(v) && '0' <= v[i] && v[i] <= '9' {
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i++
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}
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return i == len(v) && i > 1 && v[0] == '0'
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}
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func isNum(v string) bool {
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i := 0
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for i < len(v) && '0' <= v[i] && v[i] <= '9' {
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i++
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}
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return i == len(v)
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}
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func compareInt(x, y string) int {
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if x == y {
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return 0
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}
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if len(x) < len(y) {
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return -1
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}
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if len(x) > len(y) {
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return +1
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}
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if x < y {
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return -1
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} else {
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return +1
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}
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}
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func comparePrerelease(x, y string) int {
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// "When major, minor, and patch are equal, a pre-release version has
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// lower precedence than a normal version.
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// Example: 1.0.0-alpha < 1.0.0.
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// Precedence for two pre-release versions with the same major, minor,
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// and patch version MUST be determined by comparing each dot separated
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// identifier from left to right until a difference is found as follows:
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// identifiers consisting of only digits are compared numerically and
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// identifiers with letters or hyphens are compared lexically in ASCII
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// sort order. Numeric identifiers always have lower precedence than
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// non-numeric identifiers. A larger set of pre-release fields has a
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// higher precedence than a smaller set, if all of the preceding
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// identifiers are equal.
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// Example: 1.0.0-alpha < 1.0.0-alpha.1 < 1.0.0-alpha.beta <
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// 1.0.0-beta < 1.0.0-beta.2 < 1.0.0-beta.11 < 1.0.0-rc.1 < 1.0.0."
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if x == y {
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return 0
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}
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if x == "" {
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return +1
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}
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if y == "" {
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return -1
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}
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for x != "" && y != "" {
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x = x[1:] // skip - or .
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y = y[1:] // skip - or .
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var dx, dy string
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dx, x = nextIdent(x)
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dy, y = nextIdent(y)
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if dx != dy {
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ix := isNum(dx)
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iy := isNum(dy)
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if ix != iy {
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if ix {
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return -1
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} else {
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return +1
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}
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}
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if ix {
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if len(dx) < len(dy) {
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return -1
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}
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if len(dx) > len(dy) {
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return +1
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}
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}
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if dx < dy {
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return -1
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} else {
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return +1
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}
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}
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}
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if x == "" {
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return -1
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} else {
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return +1
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}
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}
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func nextIdent(x string) (dx, rest string) {
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i := 0
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for i < len(x) && x[i] != '.' {
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i++
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}
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return x[:i], x[i:]
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}
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