code.gitea.io/gitea@v1.22.3/modules/base/natural_sort.go (about)

     1  // Copyright 2017 The Gitea Authors. All rights reserved.
     2  // SPDX-License-Identifier: MIT
     3  
     4  package base
     5  
     6  import (
     7  	"unicode/utf8"
     8  
     9  	"golang.org/x/text/collate"
    10  	"golang.org/x/text/language"
    11  )
    12  
    13  func naturalSortGetRune(str string, pos int) (r rune, size int, has bool) {
    14  	if pos >= len(str) {
    15  		return 0, 0, false
    16  	}
    17  	r, size = utf8.DecodeRuneInString(str[pos:])
    18  	if r == utf8.RuneError {
    19  		r, size = rune(str[pos]), 1 // if invalid input, treat it as a single byte ascii
    20  	}
    21  	return r, size, true
    22  }
    23  
    24  func naturalSortAdvance(str string, pos int) (end int, isNumber bool) {
    25  	end = pos
    26  	for {
    27  		r, size, has := naturalSortGetRune(str, end)
    28  		if !has {
    29  			break
    30  		}
    31  		isCurRuneNum := '0' <= r && r <= '9'
    32  		if end == pos {
    33  			isNumber = isCurRuneNum
    34  			end += size
    35  		} else if isCurRuneNum == isNumber {
    36  			end += size
    37  		} else {
    38  			break
    39  		}
    40  	}
    41  	return end, isNumber
    42  }
    43  
    44  // NaturalSortLess compares two strings so that they could be sorted in natural order
    45  func NaturalSortLess(s1, s2 string) bool {
    46  	// There is a bug in Golang's collate package: https://github.com/golang/go/issues/67997
    47  	// text/collate: CompareString(collate.Numeric) returns wrong result for "0.0" vs "1.0" #67997
    48  	// So we need to handle the number parts by ourselves
    49  	c := collate.New(language.English, collate.Numeric)
    50  	pos1, pos2 := 0, 0
    51  	for pos1 < len(s1) && pos2 < len(s2) {
    52  		end1, isNum1 := naturalSortAdvance(s1, pos1)
    53  		end2, isNum2 := naturalSortAdvance(s2, pos2)
    54  		part1, part2 := s1[pos1:end1], s2[pos2:end2]
    55  		if isNum1 && isNum2 {
    56  			if part1 != part2 {
    57  				if len(part1) != len(part2) {
    58  					return len(part1) < len(part2)
    59  				}
    60  				return part1 < part2
    61  			}
    62  		} else {
    63  			if cmp := c.CompareString(part1, part2); cmp != 0 {
    64  				return cmp < 0
    65  			}
    66  		}
    67  		pos1, pos2 = end1, end2
    68  	}
    69  	return len(s1) < len(s2)
    70  }