fix #41. add new method ToKebabCase

README.md

@@ -55,6 +55,7 @@ Here is a list of functions in [strings](http://golang.org/pkg/strings) and [xst
 | [Successor](https://godoc.org/github.com/huandu/xstrings#Successor) | `String#succ` or `String#next` in Ruby | [#22](https://github.com/huandu/xstrings/issues/22) |
 | [SwapCase](https://godoc.org/github.com/huandu/xstrings#SwapCase) | `str.swapcase` in Python; `String#swapcase` in Ruby | [#12](https://github.com/huandu/xstrings/issues/12) |
 | [ToCamelCase](https://godoc.org/github.com/huandu/xstrings#ToCamelCase) | `String#camelize` in RoR | [#1](https://github.com/huandu/xstrings/issues/1) |
+| [ToKebab](https://godoc.org/github.com/huandu/xstrings#ToKebabCase) | - | [#41](https://github.com/huandu/xstrings/issues/41) |
 | [ToSnakeCase](https://godoc.org/github.com/huandu/xstrings#ToSnakeCase) | `String#underscore` in RoR | [#1](https://github.com/huandu/xstrings/issues/1) |
 | [Translate](https://godoc.org/github.com/huandu/xstrings#Translate) | `str.translate` in Python; `String#tr` in Ruby; `strtr` in PHP; `tr///` in Perl | [#21](https://github.com/huandu/xstrings/issues/21) |
 | [Width](https://godoc.org/github.com/huandu/xstrings#Width) | `mb_strwidth` in PHP | [#26](https://github.com/huandu/xstrings/issues/26) |

convert.go

@@ -72,7 +72,7 @@ func ToCamelCase(str string) string {
 }
 
 // ToSnakeCase can convert all upper case characters in a string to
-// underscore format.
+// snake case format.
 //
 // Some samples.
 //     "FirstName"  => "first_name"
@@ -85,6 +85,27 @@ func ToCamelCase(str string) string {
 //     "http2xx"    => "http_2xx"
 //     "HTTP20xOK"  => "http_20x_ok"
 func ToSnakeCase(str string) string {
+	return camelCaseToLowerCase(str, '_')
+}
+
+// ToKebabCase can convert all upper case characters in a string to
+// kebab case format.
+//
+// Some samples.
+//     "FirstName"  => "first-name"
+//     "HTTPServer" => "http-server"
+//     "NoHTTPS"    => "no-https"
+//     "GO_PATH"    => "go-path"
+//     "GO PATH"    => "go-path"      // space is converted to '-'.
+//     "GO-PATH"    => "go-path"      // hyphen is converted to '-'.
+//     "HTTP2XX"    => "http-2xx"     // insert a '-' before a number and after an alphabet.
+//     "http2xx"    => "http-2xx"
+//     "HTTP20xOK"  => "http-20x-ok"
+func ToKebabCase(str string) string {
+	return camelCaseToLowerCase(str, '-')
+}
+
+func camelCaseToLowerCase(str string, connector rune) string {
 	if len(str) == 0 {
 		return ""
 	}
@@ -93,7 +114,7 @@ func ToSnakeCase(str string) string {
 	var prev, r0, r1 rune
 	var size int
 
-	r0 = '_'
+	r0 = connector
 
 	for len(str) > 0 {
 		prev = r0
@@ -102,11 +123,11 @@ func ToSnakeCase(str string) string {
 
 		switch {
 		case r0 == utf8.RuneError:
-			buf.WriteByte(byte(str[0]))
+			buf.WriteRune(r0)
 
 		case unicode.IsUpper(r0):
-			if prev != '_' && !unicode.IsNumber(prev) {
-				buf.WriteRune('_')
+			if prev != connector && !unicode.IsNumber(prev) {
+				buf.WriteRune(connector)
 			}
 
 			buf.WriteRune(unicode.ToLower(r0))
@@ -123,7 +144,7 @@ func ToSnakeCase(str string) string {
 				break
 			}
 
-			// find next non-upper-case character and insert `_` properly.
+			// find next non-upper-case character and insert connector properly.
 			// it's designed to convert `HTTPServer` to `http_server`.
 			// if there are more than 2 adjacent upper case characters in a word,
 			// treat them as an abbreviation plus a normal word.
@@ -134,23 +155,23 @@ func ToSnakeCase(str string) string {
 
 				if r0 == utf8.RuneError {
 					buf.WriteRune(unicode.ToLower(r1))
-					buf.WriteByte(byte(str[0]))
+					buf.WriteRune(r0)
 					break
 				}
 
 				if !unicode.IsUpper(r0) {
 					if r0 == '_' || r0 == ' ' || r0 == '-' {
-						r0 = '_'
+						r0 = connector
 
 						buf.WriteRune(unicode.ToLower(r1))
 					} else if unicode.IsNumber(r0) {
 						// treat a number as an upper case rune
 						// so that both `http2xx` and `HTTP2XX` can be converted to `http_2xx`.
 						buf.WriteRune(unicode.ToLower(r1))
-						buf.WriteRune('_')
+						buf.WriteRune(connector)
 						buf.WriteRune(r0)
 					} else {
-						buf.WriteRune('_')
+						buf.WriteRune(connector)
 						buf.WriteRune(unicode.ToLower(r1))
 						buf.WriteRune(r0)
 					}
@@ -161,20 +182,20 @@ func ToSnakeCase(str string) string {
 				buf.WriteRune(unicode.ToLower(r1))
 			}
 
-			if len(str) == 0 || r0 == '_' {
+			if len(str) == 0 || r0 == connector {
 				buf.WriteRune(unicode.ToLower(r0))
 			}
 
 		case unicode.IsNumber(r0):
-			if prev != '_' && !unicode.IsNumber(prev) {
-				buf.WriteRune('_')
+			if prev != connector && !unicode.IsNumber(prev) {
+				buf.WriteRune(connector)
 			}
 
 			buf.WriteRune(r0)
 
 		default:
-			if r0 == ' ' || r0 == '-' {
-				r0 = '_'
+			if r0 == ' ' || r0 == '-' || r0 == '_' {
+				r0 = connector
 			}
 
 			buf.WriteRune(r0)

convert_test.go

@@ -9,8 +9,8 @@ import (
 	"testing"
 )
 
-func TestToSnakeCase(t *testing.T) {
-	runTestCases(t, ToSnakeCase, _M{
+func TestToSnakeCaseAndToKebabCase(t *testing.T) {
+	cases := _M{
 		"HTTPServer":         "http_server",
 		"_camelCase":         "_camel_case",
 		"NoHTTPS":            "no_https",
@@ -30,7 +30,18 @@ func TestToSnakeCase(t *testing.T) {
 
 		"  sentence case  ":                                    "__sentence_case__",
 		" Mixed-hyphen case _and SENTENCE_case and UPPER-case": "_mixed_hyphen_case__and_sentence_case_and_upper_case",
-	})
+
+		"": "",
+		"Abc\uFFFDE\uFFFDf\uFFFDd\uFFFD2\uFFFD00Z\uFFFDZZ\uFFFDZZ": "abc\uFFFD_e\uFFFDf\uFFFDd\uFFFD_2\uFFFD_00z\uFFFD_zz\uFFFD_zz",
+	}
+
+	runTestCases(t, ToSnakeCase, cases)
+
+	for k, v := range cases {
+		cases[k] = strings.Replace(v, "_", "-", -1)
+	}
+
+	runTestCases(t, ToKebabCase, cases)
 }
 
 func TestToCamelCase(t *testing.T) {
@@ -42,13 +53,17 @@ func TestToCamelCase(t *testing.T) {
 		"all":             "All",
 		"GOLANG_IS_GREAT": "GolangIsGreat",
 		"GOLANG":          "Golang",
+
+		"": "",
 	})
 }
 
 func TestSwapCase(t *testing.T) {
 	runTestCases(t, SwapCase, _M{
 		"swapCase": "SWAPcASE",
 		"Θ~λa云Ξπ":  "θ~ΛA云ξΠ",
+
+		"": "",
 	})
 }
 
@@ -57,6 +72,8 @@ func TestFirstRuneToUpper(t *testing.T) {
 		"hello, world!": "Hello, world!",
 		"Hello, world!": "Hello, world!",
 		"你好，世界！":        "你好，世界！",
+
+		"": "",
 	})
 }
 
@@ -65,6 +82,8 @@ func TestFirstRuneToLower(t *testing.T) {
 		"hello, world!": "hello, world!",
 		"Hello, world!": "hello, world!",
 		"你好，世界！":        "你好，世界！",
+
+		"": "",
 	})
 }