Improve natural sort (#29611)

Hugely simplify the code, and add more tests (only new approach could
pass)

modules/base/natural_sort.go

@@ -4,85 +4,12 @@
 package base
 
 import (
-	"math/big"
-	"unicode/utf8"
+	"golang.org/x/text/collate"
+	"golang.org/x/text/language"
 )
 
 // NaturalSortLess compares two strings so that they could be sorted in natural order
 func NaturalSortLess(s1, s2 string) bool {
-	var i1, i2 int
-	for {
-		rune1, j1, end1 := getNextRune(s1, i1)
-		rune2, j2, end2 := getNextRune(s2, i2)
-		if end1 || end2 {
-			return end1 != end2 && end1
-		}
-		dec1 := isDecimal(rune1)
-		dec2 := isDecimal(rune2)
-		var less, equal bool
-		if dec1 && dec2 {
-			i1, i2, less, equal = compareByNumbers(s1, i1, s2, i2)
-		} else if !dec1 && !dec2 {
-			equal = rune1 == rune2
-			less = rune1 < rune2
-			i1 = j1
-			i2 = j2
-		} else {
-			return rune1 < rune2
-		}
-		if !equal {
-			return less
-		}
-	}
-}
-
-func getNextRune(str string, pos int) (rune, int, bool) {
-	if pos < len(str) {
-		r, w := utf8.DecodeRuneInString(str[pos:])
-		// Fallback to ascii
-		if r == utf8.RuneError {
-			r = rune(str[pos])
-			w = 1
-		}
-		return r, pos + w, false
-	}
-	return 0, pos, true
-}
-
-func isDecimal(r rune) bool {
-	return '0' <= r && r <= '9'
-}
-
-func compareByNumbers(str1 string, pos1 int, str2 string, pos2 int) (i1, i2 int, less, equal bool) {
-	d1, d2 := true, true
-	var dec1, dec2 string
-	for d1 || d2 {
-		if d1 {
-			r, j, end := getNextRune(str1, pos1)
-			if !end && isDecimal(r) {
-				dec1 += string(r)
-				pos1 = j
-			} else {
-				d1 = false
-			}
-		}
-		if d2 {
-			r, j, end := getNextRune(str2, pos2)
-			if !end && isDecimal(r) {
-				dec2 += string(r)
-				pos2 = j
-			} else {
-				d2 = false
-			}
-		}
-	}
-	less, equal = compareBigNumbers(dec1, dec2)
-	return pos1, pos2, less, equal
-}
-
-func compareBigNumbers(dec1, dec2 string) (less, equal bool) {
-	d1, _ := big.NewInt(0).SetString(dec1, 10)
-	d2, _ := big.NewInt(0).SetString(dec2, 10)
-	cmp := d1.Cmp(d2)
-	return cmp < 0, cmp == 0
+	c := collate.New(language.English, collate.Numeric)
+	return c.CompareString(s1, s2) < 0
 }

modules/base/natural_sort_test.go

@@ -11,7 +11,7 @@ import (
 
 func TestNaturalSortLess(t *testing.T) {
 	test := func(s1, s2 string, less bool) {
-		assert.Equal(t, less, NaturalSortLess(s1, s2))
+		assert.Equal(t, less, NaturalSortLess(s1, s2), "s1=%q, s2=%q", s1, s2)
 	}
 	test("v1.20.0", "v1.2.0", false)
 	test("v1.20.0", "v1.29.0", true)
@@ -20,4 +20,11 @@ func TestNaturalSortLess(t *testing.T) {
 	test("a-1-a", "a-1-b", true)
 	test("2", "12", true)
 	test("a", "ab", true)
+
+	test("A", "b", true)
+	test("a", "B", true)
+
+	test("cafe", "café", true)
+	test("café", "cafe", false)
+	test("caff", "café", false)
 }