feat universal: simplify TrivialBiMaps

Tests: протестировано CI
commit_hash:7fce625c9dbadc65cf7dd95dcaf46b59a9aa672b

Author: apolukhin

universal/include/userver/utils/trivial_map.hpp

@@ -56,7 +56,7 @@ struct Found final {
     constexpr explicit operator std::size_t() const noexcept { return 0; }
 };
 
-template <typename Key, typename Value, typename Enabled = void>
+template <typename Key, typename Value>
 class SearchState final {
 public:
     constexpr explicit SearchState(Key key) noexcept : key_or_result_(std::in_place_index<0>, key) {}
@@ -87,7 +87,7 @@ class SearchState final {
 inline constexpr std::size_t kInvalidSize = std::numeric_limits<std::size_t>::max();
 
 template <typename Payload>
-inline constexpr bool kFitsInStringOrPayload =
+concept FitsInStringOrPayload =
     sizeof(Payload) <= sizeof(const char*) &&
     (std::is_integral_v<Payload> || std::is_enum_v<Payload> || std::is_same_v<Payload, Found>);
 
@@ -128,7 +128,7 @@ class StringOrPayload final {
     }
 
 private:
-    static_assert(kFitsInStringOrPayload<Payload>);
+    static_assert(FitsInStringOrPayload<Payload>);
 
     union DataOrPayload {
         constexpr explicit DataOrPayload(const char* data) noexcept : data(data) {}
@@ -143,8 +143,8 @@ class StringOrPayload final {
     std::size_t size_;
 };
 
-template <typename Value>
-class SearchState<std::string_view, Value, std::enable_if_t<kFitsInStringOrPayload<Value>>> {
+template <FitsInStringOrPayload Value>
+class SearchState<std::string_view, Value> {
 public:
     constexpr explicit SearchState(std::string_view key) noexcept : state_(key) {}
 
@@ -164,16 +164,14 @@ class SearchState<std::string_view, Value, std::enable_if_t<kFitsInStringOrPaylo
     StringOrPayload<Value> state_;
 };
 
-template <typename Value>
-class SearchState<zstring_view, Value, std::enable_if_t<kFitsInStringOrPayload<Value>>> final
-    : public SearchState<std::string_view, Value> {};
+template <FitsInStringOrPayload Value>
+class SearchState<zstring_view, Value> final : public SearchState<std::string_view, Value> {};
 
-template <typename Value>
-class SearchState<StringLiteral, Value, std::enable_if_t<kFitsInStringOrPayload<Value>>> final
-    : public SearchState<std::string_view, Value> {};
+template <FitsInStringOrPayload Value>
+class SearchState<StringLiteral, Value> final : public SearchState<std::string_view, Value> {};
 
-template <typename Key>
-class SearchState<Key, std::string_view, std::enable_if_t<kFitsInStringOrPayload<Key>>> final {
+template <FitsInStringOrPayload Key>
+class SearchState<Key, std::string_view> final {
 public:
     constexpr explicit SearchState(Key key) noexcept : state_(key) {}
 
@@ -192,8 +190,8 @@ class SearchState<Key, std::string_view, std::enable_if_t<kFitsInStringOrPayload
     StringOrPayload<Key> state_;
 };
 
-template <typename Key>
-class SearchState<Key, zstring_view, std::enable_if_t<kFitsInStringOrPayload<Key>>> final {
+template <FitsInStringOrPayload Key>
+class SearchState<Key, zstring_view> final {
 public:
     constexpr explicit SearchState(Key key) noexcept : state_(key) {}
 
@@ -212,8 +210,8 @@ class SearchState<Key, zstring_view, std::enable_if_t<kFitsInStringOrPayload<Key
     StringOrPayload<Key> state_;
 };
 
-template <typename Key>
-class SearchState<Key, StringLiteral, std::enable_if_t<kFitsInStringOrPayload<Key>>> final {
+template <FitsInStringOrPayload Key>
+class SearchState<Key, StringLiteral> final {
 public:
     constexpr explicit SearchState(Key key) noexcept : state_(key) {}