97 lines
2.7 KiB
Go
97 lines
2.7 KiB
Go
// Copyright (c) 2021 Tailscale Inc & 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 cmpver implements a variant of debian version number
|
|
// comparison.
|
|
//
|
|
// A version is a string consisting of alternating non-numeric and
|
|
// numeric fields. When comparing two versions, each one is broken
|
|
// down into its respective fields, and the fields are compared
|
|
// pairwise. The comparison is lexicographic for non-numeric fields,
|
|
// numeric for numeric fields. The first non-equal field pair
|
|
// determines the ordering of the two versions.
|
|
//
|
|
// This comparison scheme is a simplified version of Debian's version
|
|
// number comparisons. Debian differs in a few details of
|
|
// lexicographical field comparison, where certain characters have
|
|
// special meaning and ordering. We don't need that, because Tailscale
|
|
// version numbers don't need it.
|
|
package cmpver
|
|
|
|
import (
|
|
"fmt"
|
|
"strconv"
|
|
"strings"
|
|
"unicode"
|
|
)
|
|
|
|
// Compare returns an integer comparing two strings as version
|
|
// numbers. The result will be 0 if v1==v2, -1 if v1 < v2, and +1 if
|
|
// v1 > v2.
|
|
func Compare(v1, v2 string) int {
|
|
notNumber := func(r rune) bool { return !unicode.IsNumber(r) }
|
|
|
|
var (
|
|
f1, f2 string
|
|
n1, n2 uint64
|
|
err error
|
|
)
|
|
for v1 != "" || v2 != "" {
|
|
// Compare the non-numeric character run lexicographically.
|
|
f1, v1 = splitPrefixFunc(v1, notNumber)
|
|
f2, v2 = splitPrefixFunc(v2, notNumber)
|
|
|
|
if res := strings.Compare(f1, f2); res != 0 {
|
|
return res
|
|
}
|
|
|
|
// Compare the numeric character run numerically.
|
|
f1, v1 = splitPrefixFunc(v1, unicode.IsNumber)
|
|
f2, v2 = splitPrefixFunc(v2, unicode.IsNumber)
|
|
|
|
// ParseUint refuses to parse empty strings, which would only
|
|
// happen if we reached end-of-string. We follow the Debian
|
|
// convention that empty strings mean zero, because
|
|
// empirically that produces reasonable-feeling comparison
|
|
// behavior.
|
|
n1 = 0
|
|
if f1 != "" {
|
|
n1, err = strconv.ParseUint(f1, 10, 64)
|
|
if err != nil {
|
|
panic(fmt.Sprintf("all-number string %q didn't parse as string: %s", f1, err))
|
|
}
|
|
}
|
|
|
|
n2 = 0
|
|
if f2 != "" {
|
|
n2, err = strconv.ParseUint(f2, 10, 64)
|
|
if err != nil {
|
|
panic(fmt.Sprintf("all-number string %q didn't parse as string: %s", f2, err))
|
|
}
|
|
}
|
|
|
|
switch {
|
|
case n1 == n2:
|
|
case n1 < n2:
|
|
return -1
|
|
case n1 > n2:
|
|
return 1
|
|
}
|
|
}
|
|
|
|
// Only way to reach here is if v1 and v2 run out of fields
|
|
// simultaneously - i.e. exactly equal versions.
|
|
return 0
|
|
}
|
|
|
|
// splitPrefixFunc splits s at the first rune where f(rune) is false.
|
|
func splitPrefixFunc(s string, f func(rune) bool) (string, string) {
|
|
for i, r := range s {
|
|
if !f(r) {
|
|
return s[:i], s[i:]
|
|
}
|
|
}
|
|
return s, s[:0]
|
|
}
|