Consolidate implementation details

Author: vitaut

include/fmt/std.h

@@ -23,7 +23,6 @@
 #  include <type_traits>
 #  include <typeinfo>
 #  include <utility>
-#  include <vector>
 
 // Check FMT_CPLUSPLUS to suppress a bogus warning in MSVC.
 #  if FMT_CPLUSPLUS >= 201703L
@@ -79,11 +78,11 @@
 #  endif
 #endif
 
-#if FMT_CPP_LIB_FILESYSTEM
 FMT_BEGIN_NAMESPACE
-
 namespace detail {
 
+#if FMT_CPP_LIB_FILESYSTEM
+
 template <typename Char, typename PathChar>
 auto get_path_string(const std::filesystem::path& p,
                      const std::basic_string<PathChar>& native) {
@@ -111,8 +110,46 @@ void write_escaped_path(basic_memory_buffer<Char>& quoted,
   }
 }
 
+#endif  // FMT_CPP_LIB_FILESYSTEM
+
+#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
+template <typename Char, typename OutputIt, typename T>
+auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
+  if constexpr (has_to_string_view<T>::value)
+    return write_escaped_string<Char>(out, detail::to_string_view(v));
+  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
+  return write<Char>(out, v);
+}
+#endif
+
+#if FMT_CPP_LIB_VARIANT
+
+template <typename T>
+using variant_index_sequence =
+    std::make_index_sequence<std::variant_size<T>::value>;
+
+template <typename> struct is_variant_like_ : std::false_type {};
+template <typename... Types>
+struct is_variant_like_<std::variant<Types...>> : std::true_type {};
+
+// formattable element check.
+template <typename T, typename C> class is_variant_formattable_ {
+  template <std::size_t... Is>
+  static std::conjunction<
+      is_formattable<std::variant_alternative_t<Is, T>, C>...>
+      check(std::index_sequence<Is...>);
+
+ public:
+  static constexpr const bool value =
+      decltype(check(variant_index_sequence<T>{}))::value;
+};
+
+#endif  // FMT_CPP_LIB_VARIANT
+
 }  // namespace detail
 
+#if FMT_CPP_LIB_FILESYSTEM
+
 template <typename Char> struct formatter<std::filesystem::path, Char> {
  private:
   format_specs specs_;
@@ -177,10 +214,8 @@ class path : public std::filesystem::path {
   auto generic_system_string() const -> std::string { return generic_string(); }
 };
 
-FMT_END_NAMESPACE
 #endif  // FMT_CPP_LIB_FILESYSTEM
 
-FMT_BEGIN_NAMESPACE
 template <std::size_t N, typename Char>
 struct formatter<std::bitset<N>, Char>
     : nested_formatter<basic_string_view<Char>, Char> {
@@ -209,10 +244,8 @@ struct formatter<std::bitset<N>, Char>
 
 template <typename Char>
 struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};
-FMT_END_NAMESPACE
 
 #ifdef __cpp_lib_optional
-FMT_BEGIN_NAMESPACE
 template <typename T, typename Char>
 struct formatter<std::optional<T>, Char,
                  std::enable_if_t<is_formattable<T, Char>::value>> {
@@ -251,30 +284,9 @@ struct formatter<std::optional<T>, Char,
     return detail::write(out, ')');
   }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_optional
 
-#if defined(__cpp_lib_expected) || FMT_CPP_LIB_VARIANT
-
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename Char, typename OutputIt, typename T>
-auto write_escaped_alternative(OutputIt out, const T& v) -> OutputIt {
-  if constexpr (has_to_string_view<T>::value)
-    return write_escaped_string<Char>(out, detail::to_string_view(v));
-  if constexpr (std::is_same_v<T, Char>) return write_escaped_char(out, v);
-  return write<Char>(out, v);
-}
-
-}  // namespace detail
-
-FMT_END_NAMESPACE
-#endif
-
 #ifdef __cpp_lib_expected
-FMT_BEGIN_NAMESPACE
-
 template <typename T, typename E, typename Char>
 struct formatter<std::expected<T, E>, Char,
                  std::enable_if_t<(std::is_void<T>::value ||
@@ -301,11 +313,9 @@ struct formatter<std::expected<T, E>, Char,
     return out;
   }
 };
-FMT_END_NAMESPACE
 #endif  // __cpp_lib_expected
 
 #ifdef __cpp_lib_source_location
-FMT_BEGIN_NAMESPACE
 template <> struct formatter<std::source_location> {
   FMT_CONSTEXPR auto parse(parse_context<>& ctx) { return ctx.begin(); }
 
@@ -323,34 +333,9 @@ template <> struct formatter<std::source_location> {
     return out;
   }
 };
-FMT_END_NAMESPACE
 #endif
 
 #if FMT_CPP_LIB_VARIANT
-FMT_BEGIN_NAMESPACE
-namespace detail {
-
-template <typename T>
-using variant_index_sequence =
-    std::make_index_sequence<std::variant_size<T>::value>;
-
-template <typename> struct is_variant_like_ : std::false_type {};
-template <typename... Types>
-struct is_variant_like_<std::variant<Types...>> : std::true_type {};
-
-// formattable element check.
-template <typename T, typename C> class is_variant_formattable_ {
-  template <std::size_t... Is>
-  static std::conjunction<
-      is_formattable<std::variant_alternative_t<Is, T>, C>...>
-      check(std::index_sequence<Is...>);
-
- public:
-  static constexpr const bool value =
-      decltype(check(variant_index_sequence<T>{}))::value;
-};
-
-}  // namespace detail
 
 template <typename T> struct is_variant_like {
   static constexpr const bool value = detail::is_variant_like_<T>::value;
@@ -402,10 +387,9 @@ struct formatter<
     return out;
   }
 };
-FMT_END_NAMESPACE
+
 #endif  // FMT_CPP_LIB_VARIANT
 
-FMT_BEGIN_NAMESPACE
 template <> struct formatter<std::error_code> {
  private:
   format_specs specs_;
@@ -543,7 +527,7 @@ struct formatter<std::type_info, Char  // DEPRECATED! Mixing code unit types.
     return detail::write_demangled_name<Char>(ctx.out(), ti);
   }
 };
-#endif
+#endif  // FMT_USE_RTTI
 
 template <typename T, typename Char>
 struct formatter<
@@ -725,4 +709,5 @@ struct formatter<std::reference_wrapper<T>, Char,
 };
 
 FMT_END_NAMESPACE
+
 #endif  // FMT_STD_H_