feat: adding runelength

CHANGELOG.md

@@ -7,10 +7,11 @@
 Adding:
 
 - lo.RepeatBy
-- lo.Substring
 - lo.Subset
 - lo.Replace
 - lo.ReplaceAll
+- lo.Substring
+- lo.RuneLength
 
 ## 1.18.0 (2022-04-28)
 

README.md

@@ -100,6 +100,11 @@ Supported math helpers:
 - Range / RangeFrom / RangeWithSteps
 - Clamp
 
+Supported helpers for strings:
+
+- Substring
+- RuneLength
+
 Supported helpers for tuples:
 
 - T2 -> T9
@@ -578,21 +583,6 @@ count := lo.CountBy[int]([]int{1, 5, 1}, func(i int) bool {
 // 2
 ```
 
-### Substring
-
-Return part of a string.
-
-```go
-sub := lo.Substring("hello", 2, 3)
-// "llo"
-
-sub := lo.Substring("hello", -4, 3)
-// "ell"
-
-sub := lo.Substring("hello", -2, math.MaxUint)
-// "lo"
-```
-
 ### Subset
 
 Return part of a slice.
@@ -849,6 +839,33 @@ r3 := lo.Clamp(42, -10, 10)
 // 10
 ```
 
+### Substring
+
+Return part of a string.
+
+```go
+sub := lo.Substring("hello", 2, 3)
+// "llo"
+
+sub := lo.Substring("hello", -4, 3)
+// "ell"
+
+sub := lo.Substring("hello", -2, math.MaxUint)
+// "lo"
+```
+
+### RuneLength
+
+An alias to utf8.RuneCountInString which returns the number of runes in string.
+
+```go
+sub := lo.RuneLength("hellô")
+// 5
+
+sub := len("hellô")
+// 6
+```
+
 ### T2 -> T9
 
 Creates a tuple from a list of values.

slice.go

@@ -363,28 +363,6 @@ func CountBy[T any](collection []T, predicate func(T) bool) (count int) {
 	return count
 }
 
-// Substring return part of a string.
-func Substring[T ~string](str T, offset int, length uint) T {
-	size := len(str)
-
-	if offset < 0 {
-		offset = size + offset
-		if offset < 0 {
-			offset = 0
-		}
-	}
-
-	if offset > size {
-		return Empty[T]()
-	}
-
-	if length > uint(size)-uint(offset) {
-		length = uint(size - offset)
-	}
-
-	return str[offset : offset+int(length)]
-}
-
 // Subset return part of a slice.
 func Subset[T any](collection []T, offset int, length uint) []T {
 	size := len(collection)

slice_test.go

@@ -384,36 +384,6 @@ func TestCountBy(t *testing.T) {
 	is.Equal(count3, 0)
 }
 
-func TestSubstring(t *testing.T) {
-	is := assert.New(t)
-
-	str1 := Substring("hello", 0, 0)
-	str2 := Substring("hello", 10, 2)
-	str3 := Substring("hello", -10, 2)
-	str4 := Substring("hello", 0, 10)
-	str5 := Substring("hello", 0, 2)
-	str6 := Substring("hello", 2, 2)
-	str7 := Substring("hello", 2, 5)
-	str8 := Substring("hello", 2, 3)
-	str9 := Substring("hello", 2, 4)
-	str10 := Substring("hello", -2, 4)
-	str11 := Substring("hello", -4, 1)
-	str12 := Substring("hello", -4, math.MaxUint)
-
-	is.Equal("", str1)
-	is.Equal("", str2)
-	is.Equal("he", str3)
-	is.Equal("hello", str4)
-	is.Equal("he", str5)
-	is.Equal("ll", str6)
-	is.Equal("llo", str7)
-	is.Equal("llo", str8)
-	is.Equal("llo", str9)
-	is.Equal("lo", str10)
-	is.Equal("e", str11)
-	is.Equal("ello", str12)
-}
-
 func TestSubset(t *testing.T) {
 	is := assert.New(t)
 

string.go

@@ -0,0 +1,30 @@
+package lo
+
+import "unicode/utf8"
+
+// Substring return part of a string.
+func Substring[T ~string](str T, offset int, length uint) T {
+	size := len(str)
+
+	if offset < 0 {
+		offset = size + offset
+		if offset < 0 {
+			offset = 0
+		}
+	}
+
+	if offset > size {
+		return Empty[T]()
+	}
+
+	if length > uint(size)-uint(offset) {
+		length = uint(size - offset)
+	}
+
+	return str[offset : offset+int(length)]
+}
+
+// RuneLength is an alias to utf8.RuneCountInString which returns the number of runes in string.
+func RuneLength(str string) int {
+	return utf8.RuneCountInString(str)
+}

string_test.go

@@ -0,0 +1,45 @@
+package lo
+
+import (
+	"math"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSubstring(t *testing.T) {
+	is := assert.New(t)
+
+	str1 := Substring("hello", 0, 0)
+	str2 := Substring("hello", 10, 2)
+	str3 := Substring("hello", -10, 2)
+	str4 := Substring("hello", 0, 10)
+	str5 := Substring("hello", 0, 2)
+	str6 := Substring("hello", 2, 2)
+	str7 := Substring("hello", 2, 5)
+	str8 := Substring("hello", 2, 3)
+	str9 := Substring("hello", 2, 4)
+	str10 := Substring("hello", -2, 4)
+	str11 := Substring("hello", -4, 1)
+	str12 := Substring("hello", -4, math.MaxUint)
+
+	is.Equal("", str1)
+	is.Equal("", str2)
+	is.Equal("he", str3)
+	is.Equal("hello", str4)
+	is.Equal("he", str5)
+	is.Equal("ll", str6)
+	is.Equal("llo", str7)
+	is.Equal("llo", str8)
+	is.Equal("llo", str9)
+	is.Equal("lo", str10)
+	is.Equal("e", str11)
+	is.Equal("ello", str12)
+}
+
+func TestRuneLength(t *testing.T) {
+	is := assert.New(t)
+
+	is.Equal(5, RuneLength("hellô"))
+	is.Equal(6, len("hellô"))
+}