src: use enum class instead of enum in node_i18n

"enum class" has more advantages than "enum" because
it's strongly typed and scoped.

Refs: https://isocpp.org/wiki/faq/cpp11-language-types#enum-class

Author: deokjinkim

src/node_i18n.cc

@@ -642,13 +642,13 @@ int32_t ToUnicode(MaybeStackBuffer<char>* buf,
 int32_t ToASCII(MaybeStackBuffer<char>* buf,
                 const char* input,
                 size_t length,
-                enum idna_mode mode) {
+                idna_mode mode) {
   UErrorCode status = U_ZERO_ERROR;
   uint32_t options =                  // CheckHyphens = false; handled later
     UIDNA_CHECK_BIDI |                // CheckBidi = true
     UIDNA_CHECK_CONTEXTJ |            // CheckJoiners = true
     UIDNA_NONTRANSITIONAL_TO_ASCII;   // Nontransitional_Processing
-  if (mode == IDNA_STRICT) {
+  if (mode == idna_mode::IDNA_STRICT) {
     options |= UIDNA_USE_STD3_RULES;  // UseSTD3ASCIIRules = beStrict
                                       // VerifyDnsLength = beStrict;
                                       //   handled later
@@ -696,14 +696,15 @@ int32_t ToASCII(MaybeStackBuffer<char>* buf,
   info.errors &= ~UIDNA_ERROR_LEADING_HYPHEN;
   info.errors &= ~UIDNA_ERROR_TRAILING_HYPHEN;
 
-  if (mode != IDNA_STRICT) {
+  if (mode != idna_mode::IDNA_STRICT) {
     // VerifyDnsLength = beStrict
     info.errors &= ~UIDNA_ERROR_EMPTY_LABEL;
     info.errors &= ~UIDNA_ERROR_LABEL_TOO_LONG;
     info.errors &= ~UIDNA_ERROR_DOMAIN_NAME_TOO_LONG;
   }
 
-  if (U_FAILURE(status) || (mode != IDNA_LENIENT && info.errors != 0)) {
+  if (U_FAILURE(status) ||
+     (mode != idna_mode::IDNA_LENIENT && info.errors != 0)) {
     len = -1;
     buf->SetLength(0);
   } else {
@@ -741,7 +742,7 @@ static void ToASCII(const FunctionCallbackInfo<Value>& args) {
   Utf8Value val(env->isolate(), args[0]);
   // optional arg
   bool lenient = args[1]->BooleanValue(env->isolate());
-  enum idna_mode mode = lenient ? IDNA_LENIENT : IDNA_DEFAULT;
+  idna_mode mode = lenient ? idna_mode::IDNA_LENIENT : idna_mode::IDNA_DEFAULT;
 
   MaybeStackBuffer<char> buf;
   int32_t len = ToASCII(&buf, *val, val.length(), mode);

src/node_i18n.h

@@ -42,7 +42,7 @@ bool InitializeICUDirectory(const std::string& path);
 
 void SetDefaultTimeZone(const char* tzid);
 
-enum idna_mode {
+enum class idna_mode {
   // Default mode for maximum compatibility.
   IDNA_DEFAULT,
   // Ignore all errors in IDNA conversion, if possible.
@@ -58,7 +58,7 @@ enum idna_mode {
 int32_t ToASCII(MaybeStackBuffer<char>* buf,
                 const char* input,
                 size_t length,
-                enum idna_mode mode = IDNA_DEFAULT);
+                idna_mode mode = idna_mode::IDNA_DEFAULT);
 
 // Implements the WHATWG URL Standard "domain to Unicode" algorithm.
 // https://url.spec.whatwg.org/#concept-domain-to-unicode