doc: update document and add playgound example for strutil package

strutil/string.go

@@ -9,9 +9,8 @@ import (
 	"unicode/utf8"
 )
 
-// CamelCase covert string to camelCase string.
-// non letters and numbers will be ignored
-// eg. "Foo-#1😄$_%^&*(1bar" => "foo11Bar"
+// CamelCase coverts string to camelCase string. Non letters and numbers will be ignored.
+// Play: https://go.dev/play/p/9eXP3tn2tUy
 func CamelCase(s string) string {
 	var builder strings.Builder
 
@@ -28,6 +27,7 @@ func CamelCase(s string) string {
 }
 
 // Capitalize converts the first character of a string to upper case and the remaining to lower case.
+// Play: https://go.dev/play/p/2OAjgbmAqHZ
 func Capitalize(s string) string {
 	result := make([]rune, len(s))
 	for i, v := range s {
@@ -42,6 +42,7 @@ func Capitalize(s string) string {
 }
 
 // UpperFirst converts the first character of string to upper case.
+// Play: https://go.dev/play/p/sBbBxRbs8MM
 func UpperFirst(s string) string {
 	if len(s) == 0 {
 		return ""
@@ -54,6 +55,7 @@ func UpperFirst(s string) string {
 }
 
 // LowerFirst converts the first character of string to lower case.
+// Play: https://go.dev/play/p/CbzAyZmtJwL
 func LowerFirst(s string) string {
 	if len(s) == 0 {
 		return ""
@@ -67,6 +69,7 @@ func LowerFirst(s string) string {
 
 // PadEnd pads string on the right side if it's shorter than size.
 // Padding characters are truncated if they exceed size.
+// Play: https://go.dev/play/p/9xP8rN0vz--
 func PadEnd(source string, size int, padStr string) string {
 	len1 := len(source)
 	len2 := len(padStr)
@@ -86,6 +89,7 @@ func PadEnd(source string, size int, padStr string) string {
 
 // PadStart pads string on the left side if it's shorter than size.
 // Padding characters are truncated if they exceed size.
+// Play: https://go.dev/play/p/xpTfzArDfvT
 func PadStart(source string, size int, padStr string) string {
 	len1 := len(source)
 	len2 := len(padStr)
@@ -103,39 +107,36 @@ func PadStart(source string, size int, padStr string) string {
 	return fill[0:size-len1] + source
 }
 
-// KebabCase covert string to kebab-case
-// non letters and numbers will be ignored
-// eg. "Foo-#1😄$_%^&*(1bar" => "foo-1-1-bar"
+// KebabCase coverts string to kebab-case, non letters and numbers will be ignored.
+// Play: https://go.dev/play/p/dcZM9Oahw-Y
 func KebabCase(s string) string {
 	result := splitIntoStrings(s, false)
 	return strings.Join(result, "-")
 }
 
-// UpperKebabCase covert string to upper KEBAB-CASE
-// non letters and numbers will be ignored
-// eg. "Foo-#1😄$_%^&*(1bar" => "FOO-1-1-BAR"
+// UpperKebabCase coverts string to upper KEBAB-CASE, non letters and numbers will be ignored
+// Play: https://go.dev/play/p/zDyKNneyQXk
 func UpperKebabCase(s string) string {
 	result := splitIntoStrings(s, true)
 	return strings.Join(result, "-")
 }
 
-// SnakeCase covert string to snake_case
-// non letters and numbers will be ignored
-// eg. "Foo-#1😄$_%^&*(1bar" => "foo_1_1_bar"
+// SnakeCase coverts string to snake_case, non letters and numbers will be ignored
+// Play: https://go.dev/play/p/tgzQG11qBuN
 func SnakeCase(s string) string {
 	result := splitIntoStrings(s, false)
 	return strings.Join(result, "_")
 }
 
-// UpperSnakeCase covert string to upper SNAKE_CASE
-// non letters and numbers will be ignored
-// eg. "Foo-#1😄$_%^&*(1bar" => "FOO_1_1_BAR"
+// UpperSnakeCase coverts string to upper SNAKE_CASE, non letters and numbers will be ignored
+// Play: https://go.dev/play/p/4COPHpnLx38
 func UpperSnakeCase(s string) string {
 	result := splitIntoStrings(s, true)
 	return strings.Join(result, "_")
 }
 
-// Before create substring in source string before position when char first appear
+// Before returns the substring of the source string up to the first occurrence of the specified string.
+// Play: https://go.dev/play/p/JAWTZDS4F5w
 func Before(s, char string) string {
 	if s == "" || char == "" {
 		return s
@@ -144,7 +145,8 @@ func Before(s, char string) string {
 	return s[0:i]
 }
 
-// BeforeLast create substring in source string before position when char last appear
+// BeforeLast returns the substring of the source string up to the last occurrence of the specified string.
+// Play: https://go.dev/play/p/pJfXXAoG_Te
 func BeforeLast(s, char string) string {
 	if s == "" || char == "" {
 		return s
@@ -163,7 +165,8 @@ func After(s, char string) string {
 	return s[i+len(char):]
 }
 
-// AfterLast create substring in source string after position when char last appear
+// AfterLast returns the substring after the last occurrence of a specified string in the source string.
+// Play: https://go.dev/play/p/1TegARrb8Yn
 func AfterLast(s, char string) string {
 	if s == "" || char == "" {
 		return s
@@ -173,6 +176,7 @@ func AfterLast(s, char string) string {
 }
 
 // IsString check if the value data type is string or not.
+// Play: https://go.dev/play/p/IOgq7oF9ERm
 func IsString(v any) bool {
 	if v == nil {
 		return false
@@ -185,7 +189,8 @@ func IsString(v any) bool {
 	}
 }
 
-// Reverse return string whose char order is reversed to the given string
+// Reverse returns string whose char order is reversed to the given string.
+// Play: https://go.dev/play/p/adfwalJiecD
 func Reverse(s string) string {
 	r := []rune(s)
 	for i, j := 0, len(r)-1; i < j; i, j = i+1, j-1 {
@@ -194,7 +199,8 @@ func Reverse(s string) string {
 	return string(r)
 }
 
-// Wrap a string with another string.
+// Wrap a string with given string.
+// Play: https://go.dev/play/p/KoZOlZDDt9y
 func Wrap(str string, wrapWith string) string {
 	if str == "" || wrapWith == "" {
 		return str
@@ -207,7 +213,8 @@ func Wrap(str string, wrapWith string) string {
 	return sb.String()
 }
 
-// Unwrap a given string from anther string. will change str value
+// Unwrap a given string from anther string. will change source string.
+// Play: https://go.dev/play/p/Ec2q4BzCpG-
 func Unwrap(str string, wrapToken string) string {
 	if str == "" || wrapToken == "" {
 		return str
@@ -225,7 +232,8 @@ func Unwrap(str string, wrapToken string) string {
 	return str
 }
 
-// SplitEx split a given string whether the result contains empty string
+// SplitEx split a given string which can control the result slice contains empty string or not.
+// Play: https://go.dev/play/p/Us-ySSbWh-3
 func SplitEx(s, sep string, removeEmptyString bool) []string {
 	if sep == "" {
 		return []string{}

strutil/string_example_test.go

@@ -1,6 +1,8 @@
 package strutil
 
-import "fmt"
+import (
+	"fmt"
+)
 
 func ExampleAfter() {
 	result1 := After("foo", "")
@@ -191,6 +193,7 @@ func ExamplePadEnd() {
 	result4 := PadEnd("foo", 4, "bar")
 	result5 := PadEnd("foo", 5, "bar")
 	result6 := PadEnd("foo", 6, "bar")
+	result7 := PadEnd("foo", 7, "bar")
 
 	fmt.Println(result1)
 	fmt.Println(result2)
@@ -198,6 +201,7 @@ func ExamplePadEnd() {
 	fmt.Println(result4)
 	fmt.Println(result5)
 	fmt.Println(result6)
+	fmt.Println(result7)
 	// Output:
 	// foo
 	// foo
@@ -205,6 +209,7 @@ func ExamplePadEnd() {
 	// foob
 	// fooba
 	// foobar
+	// foobarb
 }
 
 func ExamplePadStart() {
@@ -214,6 +219,7 @@ func ExamplePadStart() {
 	result4 := PadStart("foo", 4, "bar")
 	result5 := PadStart("foo", 5, "bar")
 	result6 := PadStart("foo", 6, "bar")
+	result7 := PadStart("foo", 7, "bar")
 
 	fmt.Println(result1)
 	fmt.Println(result2)
@@ -221,6 +227,7 @@ func ExamplePadStart() {
 	fmt.Println(result4)
 	fmt.Println(result5)
 	fmt.Println(result6)
+	fmt.Println(result7)
 	// Output:
 	// foo
 	// foo
@@ -228,6 +235,7 @@ func ExamplePadStart() {
 	// bfoo
 	// bafoo
 	// barfoo
+	// barbfoo
 }
 
 func ExampleReverse() {