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// Copyright 2017 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package base
import (
"unicode/utf8"
"golang.org/x/text/collate"
"golang.org/x/text/language"
)
func naturalSortGetRune(str string, pos int) (r rune, size int, has bool) {
if pos >= len(str) {
return 0, 0, false
}
r, size = utf8.DecodeRuneInString(str[pos:])
if r == utf8.RuneError {
r, size = rune(str[pos]), 1 // if invalid input, treat it as a single byte ascii
}
return r, size, true
}
func naturalSortAdvance(str string, pos int) (end int, isNumber bool) {
end = pos
for {
r, size, has := naturalSortGetRune(str, end)
if !has {
break
}
isCurRuneNum := '0' <= r && r <= '9'
if end == pos {
isNumber = isCurRuneNum
end += size
} else if isCurRuneNum == isNumber {
end += size
} else {
break
}
}
return end, isNumber
}
// NaturalSortLess compares two strings so that they could be sorted in natural order
func NaturalSortLess(s1, s2 string) bool {
// There is a bug in Golang's collate package: https://github.com/golang/go/issues/67997
// text/collate: CompareString(collate.Numeric) returns wrong result for "0.0" vs "1.0" #67997
// So we need to handle the number parts by ourselves
c := collate.New(language.English, collate.Numeric)
pos1, pos2 := 0, 0
for pos1 < len(s1) && pos2 < len(s2) {
end1, isNum1 := naturalSortAdvance(s1, pos1)
end2, isNum2 := naturalSortAdvance(s2, pos2)
part1, part2 := s1[pos1:end1], s2[pos2:end2]
if isNum1 && isNum2 {
if part1 != part2 {
if len(part1) != len(part2) {
return len(part1) < len(part2)
}
return part1 < part2
}
} else {
if cmp := c.CompareString(part1, part2); cmp != 0 {
return cmp < 0
}
}
pos1, pos2 = end1, end2
}
return len(s1) < len(s2)
}
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