fix toCamelCase function

Author: vetcher

.gitignore

@@ -12,3 +12,5 @@
 
 # Project-local glide cache, RE: https://github.com/Masterminds/glide/issues/736
 .glide/
+
+.idea/

core.go

@@ -17,7 +17,7 @@ var (
 	// ToCamelCase converts string to CamelCase. All space symbols, `_`, `.` and `-` will be removed. First symbol will be capital.
 	ToCamelCase = toCamelCase(true, unicode.ToUpper)
 	// ToCamelCase converts string to CamelCase. All space symbols, `_`, `.` and `-` will be removed. First symbol will be capital.
-	ToCamelCaseLowerFirst = toCamelCase(false, unicode.ToUpper)
+	ToCamelCaseLowerFirst = toCamelCaseLower()
 	// ToNoCase returns input's string. Should be used for mocking, tests, etc.
 	ToNoCase = func(s string) string { return s }
 )
@@ -66,6 +66,43 @@ func toCamelCase(upperFirst bool, runeConv func(rune) rune) func(string) string
 	}
 }
 
+func toCamelCaseLower() func(string) string {
+	return func(s string) string {
+		in := []rune(s)
+		var runes []rune
+		max, m := len(in), 0
+		for i, r := range in {
+			if !isExtendedSpace(r) && (i+1 < max && unicode.IsUpper(in[i+1])) {
+				runes = append(runes, unicode.ToLower(r))
+				continue
+			}
+			m = i
+			break
+		}
+		if len(in[m:]) == 1 {
+			return string(append(runes, unicode.ToLower(in[m])))
+		}
+		for i, r := range in[m:] {
+			if isExtendedSpace(r) {
+				continue
+			}
+			if unicode.IsUpper(r) {
+				if i+m > 0 {
+					runes = append(runes, r)
+				} else {
+					runes = append(runes, unicode.ToLower(r))
+				}
+				continue
+			}
+			if i+m > 0 && isExtendedSpace(in[i+m-1]) && unicode.IsLower(r) {
+				r = unicode.ToUpper(r)
+			}
+			runes = append(runes, r)
+		}
+		return string(runes)
+	}
+}
+
 func isExtendedSpace(r rune) bool {
 	return unicode.IsSpace(r) || r == '_' || r == '-' || r == '.'
 }

core_test.go

@@ -21,6 +21,8 @@ var testCases = []string{
 	"ТестКириллицы",
 	"Ещё-Тест Кириллицы",
 	"и-ещё-тест.Кириллицы",
+	"MQ",
+	"MTT",
 }
 
 func Test_ToSnakeCase(t *testing.T) {
@@ -40,6 +42,8 @@ func Test_ToSnakeCase(t *testing.T) {
 		"тест_кириллицы",
 		"ещё_тест_кириллицы",
 		"и_ещё_тест_кириллицы",
+		"mq",
+		"mtt",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")
@@ -70,6 +74,8 @@ func Test_ToUrlSnakeCase(t *testing.T) {
 		"тест-кириллицы",
 		"ещё-тест-кириллицы",
 		"и-ещё-тест-кириллицы",
+		"mq",
+		"mtt",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")
@@ -100,6 +106,8 @@ func Test_ToDotSnakeCase(t *testing.T) {
 		"тест.кириллицы",
 		"ещё.тест.кириллицы",
 		"и.ещё.тест.кириллицы",
+		"mq",
+		"mtt",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")
@@ -130,6 +138,8 @@ func Test_ToCamelCase(t *testing.T) {
 		"ТестКириллицы",
 		"ЕщёТестКириллицы",
 		"ИЕщёТестКириллицы",
+		"MQ",
+		"MTT",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")
@@ -146,20 +156,22 @@ func Test_ToCamelCase(t *testing.T) {
 func Test_ToCamelCaseLowerFirst(t *testing.T) {
 	answers := []string{
 		"stringService",
-		"StringService",
-		"Stringservice",
 		"stringService",
-		"StringService",
+		"stringservice",
+		"stringService",
+		"stringService",
 		"stringService",
-		"JSONService",
 		"jsonService",
-		"JSONServiceV2",
-		"JSONServiceV2",
-		"StringService",
-		"StringService",
-		"ТестКириллицы",
-		"ЕщёТестКириллицы",
+		"jsonService",
+		"jsonServiceV2",
+		"jsonServiceV2",
+		"stringService",
+		"stringService",
+		"тестКириллицы",
+		"ещёТестКириллицы",
 		"иЕщёТестКириллицы",
+		"mq",
+		"mtt",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")
@@ -190,6 +202,8 @@ func Test_ToNoCase(t *testing.T) {
 		"ТестКириллицы",
 		"Ещё-Тест Кириллицы",
 		"и-ещё-тест.Кириллицы",
+		"MQ",
+		"MTT",
 	}
 	if len(testCases) != len(answers) {
 		t.Fatal("different amount of test cases and expected answers")