feat: merge some new functions from rc branch

strutil/string.go

@@ -5,6 +5,7 @@
 package strutil
 
 import (
+	"errors"
 	"regexp"
 	"strings"
 	"unicode"
@@ -537,3 +538,24 @@ func SubInBetween(str string, start string, end string) string {
 
 	return ""
 }
+
+// HammingDistance calculates the Hamming distance between two strings.
+// The Hamming distance is the number of positions at which the corresponding symbols are different.
+// This func returns an error if the input strings are of unequal lengths.
+func HammingDistance(a, b string) (int, error) {
+	if len(a) != len(b) {
+		return -1, errors.New("a length and b length are unequal")
+	}
+
+	ar := []rune(a)
+	br := []rune(b)
+
+	var distance int
+	for i, codepoint := range ar {
+		if codepoint != br[i] {
+			distance++
+		}
+	}
+
+	return distance, nil
+}

strutil/string_test.go

@@ -224,6 +224,29 @@ func TestBeforeLast(t *testing.T) {
 	assert.NotEqual("github.com/", BeforeLast("github.com/test/test/lancet", "test"))
 }
 
+func TestHammingDistance(t *testing.T) {
+	assert := internal.NewAssert(t, "HammingDistance")
+
+	hd := func(a, b string) int {
+		c, _ := HammingDistance(a, b)
+		return c
+	}
+
+	assert.Equal(0, hd(" ", " "))
+	assert.Equal(1, hd(" ", "c"))
+	assert.Equal(1, hd("a", "d"))
+	assert.Equal(1, hd("a", " "))
+	assert.Equal(1, hd("a", "f"))
+
+	assert.Equal(0, hd("", ""))
+	assert.Equal(-1, hd("abc", "ab"))
+	assert.Equal(3, hd("abc", "def"))
+	assert.Equal(-1, hd("kitten", "sitting"))
+	assert.Equal(1, hd("ö", "ü"))
+	assert.Equal(0, hd("日本語", "日本語"))
+	assert.Equal(3, hd("日本語", "語日本"))
+}
+
 func TestAfter(t *testing.T) {
 	assert := internal.NewAssert(t, "TestAfter")