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// -*- Mode: Go; indent-tabs-mode: t -*-
/*
* Copyright (C) 2014-2017 Canonical Ltd
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
package strutil
import (
"fmt"
"strings"
)
// golang: seriously? that's sad!
func max(a, b int) int {
if a < b {
return b
}
return a
}
//go:generate go run $GOINVOKEFLAGS ./chrorder/main.go -package=strutil -output=chrorder.go
func cmpString(as, bs string) int {
for i := 0; i < max(len(as), len(bs)); i++ {
var a uint8
var b uint8
if i < len(as) {
a = as[i]
}
if i < len(bs) {
b = bs[i]
}
if chOrder[a] < chOrder[b] {
return -1
}
if chOrder[a] > chOrder[b] {
return +1
}
}
return 0
}
func trimLeadingZeroes(a string) string {
for i := 0; i < len(a); i++ {
if a[i] != '0' {
return a[i:]
}
}
return ""
}
// a and b both match /[0-9]+/
func cmpNumeric(a, b string) int {
a = trimLeadingZeroes(a)
b = trimLeadingZeroes(b)
switch d := len(a) - len(b); {
case d > 0:
return 1
case d < 0:
return -1
}
for i := 0; i < len(a); i++ {
switch {
case a[i] > b[i]:
return 1
case a[i] < b[i]:
return -1
}
}
return 0
}
func matchEpoch(a string) bool {
if len(a) == 0 {
return false
}
if a[0] < '0' || a[0] > '9' {
return false
}
var i int
for i = 1; i < len(a) && a[i] >= '0' && a[i] <= '9'; i++ {
}
return i < len(a) && a[i] == ':'
}
// versionIsValid returns true if the given string is a valid
// version number according to the debian policy
func versionIsValid(a string) bool {
return !matchEpoch(a)
}
func nextFrag(s string) (frag, rest string, numeric bool) {
if len(s) == 0 {
return "", "", false
}
var i int
if s[0] >= '0' && s[0] <= '9' {
// is digit
for i = 1; i < len(s) && s[i] >= '0' && s[i] <= '9'; i++ {
}
numeric = true
} else {
// not digit
for i = 1; i < len(s) && (s[i] < '0' || s[i] > '9'); i++ {
}
}
return s[:i], s[i:], numeric
}
func compareSubversion(va, vb string) int {
var a, b string
var anum, bnum bool
var res int
for res == 0 {
a, va, anum = nextFrag(va)
b, vb, bnum = nextFrag(vb)
if a == "" && b == "" {
break
}
if anum && bnum {
res = cmpNumeric(a, b)
} else {
res = cmpString(a, b)
}
}
return res
}
// VersionCompare compare two version strings that follow the debian
// version policy and
// Returns:
//
// -1 if a is smaller than b
// 0 if a equals b
// +1 if a is bigger than b
func VersionCompare(va, vb string) (res int, err error) {
// FIXME: return err here instead
if !versionIsValid(va) {
return 0, fmt.Errorf("invalid version %q", va)
}
if !versionIsValid(vb) {
return 0, fmt.Errorf("invalid version %q", vb)
}
var sa, sb string
if ia := strings.LastIndexByte(va, '-'); ia < 0 {
sa = "0"
} else {
va, sa = va[:ia], va[ia+1:]
}
if ib := strings.LastIndexByte(vb, '-'); ib < 0 {
sb = "0"
} else {
vb, sb = vb[:ib], vb[ib+1:]
}
// the main version number (before the "-")
res = compareSubversion(va, vb)
if res != 0 {
return res, nil
}
// the subversion revision behind the "-"
return compareSubversion(sa, sb), nil
}
|
