From 962dc18ee4827b464764ec3708be3d00a9143971 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Thu, 21 Mar 2019 22:22:02 +0800
Subject: ...

---
 src/util/format.hpp | 42 ++++++++++++++++++++++++------------------
 1 file changed, 24 insertions(+), 18 deletions(-)

(limited to 'src/util')

diff --git a/src/util/format.hpp b/src/util/format.hpp
index 874c5b43..7c1cee05 100644
--- a/src/util/format.hpp
+++ b/src/util/format.hpp
@@ -5,26 +5,29 @@
 
 namespace cru::util {
 namespace details {
-constexpr StringView PlaceHolder(type_tag<String>) { return StringView(L"{}"); }
+template <typename T>
+struct TypeTag {};
 
-constexpr MultiByteStringView PlaceHolder(type_tag<MultiByteString>) {
+constexpr StringView PlaceHolder(TypeTag<String>) { return StringView(L"{}"); }
+
+constexpr MultiByteStringView PlaceHolder(TypeTag<MultiByteString>) {
   return MultiByteStringView("{}");
 }
 
 template <typename TString>
 void FormatInternal(TString& string) {
-  const auto find_result = string.find(PlaceHolder(type_tag<TString>{}));
+  const auto find_result = string.find(PlaceHolder(TypeTag<TString>{}));
   if (find_result != TString::npos)
     throw std::invalid_argument("There is more placeholders than args.");
 }
 
 template <typename TString, typename T, typename... TRest>
 void FormatInternal(TString& string, const T& arg, const TRest&... args) {
-  const auto find_result = string.find(PlaceHolder(type_tag<TString>{}));
+  const auto find_result = string.find(PlaceHolder(TypeTag<TString>{}));
   if (find_result == TString::npos)
     throw std::invalid_argument("There is less placeholders than args.");
 
-  string.replace(find_result, 2, FormatToString(arg, type_tag<TString>{}));
+  string.replace(find_result, 2, FormatToString(arg, TypeTag<TString>{}));
   FormatInternal<TString>(string, args...);
 }
 }  // namespace details
@@ -43,13 +46,13 @@ MultiByteString Format(const MultiByteStringView& format, const T&... args) {
   return result;
 }
 
-#define CRU_FORMAT_NUMBER(type)                                       \
-  inline String FormatToString(const type number, type_tag<String>) { \
-    return std::to_wstring(number);                                   \
-  }                                                                   \
-  inline MultiByteString FormatToString(const type number,            \
-                                        type_tag<MultiByteString>) {  \
-    return std::to_string(number);                                    \
+#define CRU_FORMAT_NUMBER(type)                                               \
+  inline String FormatToString(const type number, details::TypeTag<String>) { \
+    return std::to_wstring(number);                                           \
+  }                                                                           \
+  inline MultiByteString FormatToString(const type number,                    \
+                                        details::TypeTag<MultiByteString>) {  \
+    return std::to_string(number);                                            \
   }
 
 CRU_FORMAT_NUMBER(int)
@@ -65,30 +68,33 @@ CRU_FORMAT_NUMBER(double)
 
 #undef CRU_FORMAT_NUMBER
 
-inline StringView FormatToString(const String& string, type_tag<String>) {
+inline StringView FormatToString(const String& string,
+                                 details::TypeTag<String>) {
   return string;
 }
 
 inline MultiByteString FormatToString(const MultiByteString& string,
-                                      type_tag<MultiByteString>) {
+                                      details::TypeTag<MultiByteString>) {
   return string;
 }
 
-inline StringView FormatToString(const StringView& string, type_tag<String>) {
+inline StringView FormatToString(const StringView& string,
+                                 details::TypeTag<String>) {
   return string;
 }
 
 inline MultiByteStringView FormatToString(const MultiByteStringView& string,
-                                          type_tag<MultiByteString>) {
+                                          details::TypeTag<MultiByteString>) {
   return string;
 }
 
-inline StringView FormatToString(const wchar_t* string, type_tag<String>) {
+inline StringView FormatToString(const wchar_t* string,
+                                 details::TypeTag<String>) {
   return StringView(string);
 }
 
 inline MultiByteStringView FormatToString(const char* string,
-                                          type_tag<MultiByteString>) {
+                                          details::TypeTag<MultiByteString>) {
   return MultiByteString(string);
 }
 }  // namespace cru::util
-- 
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