Treat acronyms as whole words

Closes #5

snake.go

@@ -11,9 +11,17 @@ func ToSnake(s string) string {
 	s = strings.Trim(s, " ")
 	n := ""
 	for i, v := range s {
-		if i > 0 && v >= 'A' && v <= 'Z' && n[len(n)-1] != '_' {
+		// treat acronyms as words, eg for JSONData -> JSON is a whole word
+		nextIsCapital := false
+		if i + 1 < len(s) {
+			w := s[i+1]
+			nextIsCapital = w >= 'A' && w <= 'Z'
+		}
+		if i > 0 && v >= 'A' && v <= 'Z' && n[len(n)-1] != '_' && !nextIsCapital {
+			// add underscore if next letter is a capital
 			n += "_" + string(v)
 		} else if v == ' ' {
+			// replace spaces with underscores
 			n += "_"
 		} else {
 			n = n + string(v)

snake_test.go

@@ -20,6 +20,7 @@ func TestToSnake(t *testing.T) {
 		[]string{"manyManyWords", "many_many_words"},
 		[]string{"AnyKind of_string", "any_kind_of_string"},
 		[]string{"numbers2and55with000", "numbers_2_and_55_with_000"},
+		[]string{"JSONData", "json_data"},
 	}
 	for _, i := range cases {
 		in := i[0]