add proper encoding of control char

encode_builder.go

@@ -1,5 +1,7 @@
 package gojay
 
+const hex = "0123456789abcdef"
+
 // grow grows b's capacity, if necessary, to guarantee space for
 // another n bytes. After grow(n), at least n bytes can be written to b
 // without another allocation. If n is negative, grow panics.
@@ -36,9 +38,14 @@ func (enc *Encoder) writeString(s string) {
 func (enc *Encoder) writeStringEscape(s string) {
 	l := len(s)
 	for i := 0; i < l; i++ {
-		switch s[i] {
+		c := s[i]
+		if c >= 0x20 && c != '\\' && c != '"' {
+			enc.writeByte(c)
+			continue
+		}
+		switch c {
 		case '\\', '"':
-			enc.writeTwoBytes('\\', s[i])
+			enc.writeTwoBytes('\\', c)
 		case '\n':
 			enc.writeTwoBytes('\\', 'n')
 		case '\f':
@@ -50,8 +57,9 @@ func (enc *Encoder) writeStringEscape(s string) {
 		case '\t':
 			enc.writeTwoBytes('\\', 't')
 		default:
-			enc.writeByte(s[i])
+			enc.writeString(`\u00`)
+			enc.writeTwoBytes(hex[c>>4], hex[c&0xF])
 		}
+		continue
 	}
-
 }

encode_string_test.go

@@ -92,6 +92,18 @@ func TestEncoderStringEncodeAPI(t *testing.T) {
 			builder.String(),
 			"Result of marshalling is different as the one expected")
 	})
+	t.Run("escaped-control-char", func(t *testing.T) {
+		str := "\u001b"
+		builder := &strings.Builder{}
+		enc := NewEncoder(builder)
+		err := enc.EncodeString(str)
+		assert.Nil(t, err, "Error should be nil")
+		assert.Equal(
+			t,
+			`"\u001b"`,
+			builder.String(),
+			"Result of marshalling is different as the one expected")
+	})
 	t.Run("escaped-sequence3", func(t *testing.T) {
 		str := "hello \f world 𝄞"
 		builder := &strings.Builder{}