Implement textcase.KebabCase(), a "kebab-case" naming convention

Author: VojtechVitek

README.md

@@ -2,7 +2,7 @@
 
 [![GoDoc Widget]][GoDoc]
 
-Golang pkg to convert any text input to camelCase, PascalCase or snake_case naming convention. Removes all whitespaces and special characters. Supports Unicode characters.
+Golang pkg to convert any text input to **camelCase**, **PascalCase**, **snake_case** or **kebab-case** naming convention. Removes all whitespaces and special characters. Supports Unicode characters.
 
 ## Usage
 ```go
@@ -16,6 +16,9 @@ textcase.PascalCase("Hello World!")
 
 textcase.SnakeCase("Hello World!")
 // hello_world
+
+textcase.KebabCase("Hello World!")
+// hello-world
 ```
 
 ## Unicode support

kebab.go

@@ -0,0 +1,31 @@
+package textcase
+
+import (
+	"bytes"
+	"unicode"
+	"unicode/utf8"
+)
+
+// Converts input string to "kebab-case" naming convention.
+// Removes all whitespace and special characters. Supports Unicode characters.
+func KebabCase(str string) string {
+	var b bytes.Buffer
+
+	state := idle
+	for i := 0; i < len(str); {
+		r, size := utf8.DecodeRuneInString(str[i:])
+		i += size
+		state = state.next(r)
+		switch state {
+		case firstAlphaNum, alphaNum:
+			b.WriteRune(unicode.ToLower(r))
+		case delimiter:
+			b.WriteByte('-')
+		}
+	}
+	if (state == idle || state == delimiter) && b.Len() > 0 {
+		b.Truncate(b.Len() - 1)
+	}
+
+	return b.String()
+}

textcase_test.go

@@ -29,14 +29,26 @@ func TestTextCases(t *testing.T) {
 	}
 
 	for _, test := range tt {
+		// camelCase
 		if got := CamelCase(test.in); got != test.camel {
 			t.Errorf("unexpected camelCase for input(%q), got %q, want %q", test.in, got, test.camel)
 		}
-		if got := PascalCase(test.in); got != strings.Title(test.camel) {
-			t.Errorf("unexpected PascalCase for input(%q), got %q, want %q", test.in, got, strings.Title(test.camel))
+
+		// PascalCase
+		testPascal := strings.Title(test.camel)
+		if got := PascalCase(test.in); got != testPascal {
+			t.Errorf("unexpected PascalCase for input(%q), got %q, want %q", test.in, got, testPascal)
 		}
+
+		// snake_case
 		if got := SnakeCase(test.in); got != test.snake {
 			t.Errorf("unexpected snake_case for input(%q), got %q, want %q", test.in, got, test.snake)
 		}
+
+		// kebab-case
+		testKebab := strings.ReplaceAll(test.snake, "_", "-")
+		if got := KebabCase(test.in); got != testKebab {
+			t.Errorf("unexpected kebab-case for input(%q), got %q, want %q", test.in, got, testKebab)
+		}
 	}
 }