From 2df7b3871cb07136d01601c5f2cedeeb16dbf382 Mon Sep 17 00:00:00 2001
From: DH <dh.rpcs3@gmail.com>
Date: Sat, 4 Oct 2025 14:29:29 +0300
Subject: [PATCH] rx/refl: add C arrays support & reduce binary size Use
 StaticString constant to keep only used part of template string Use bisect
 for field count query

---
 rx/include/rx/refl.hpp | 92 +++++++++++++++++++++++++++++-------------
 1 file changed, 63 insertions(+), 29 deletions(-)

diff --git a/rx/include/rx/refl.hpp b/rx/include/rx/refl.hpp
index 1341bd364..c81a5a665 100644
--- a/rx/include/rx/refl.hpp
+++ b/rx/include/rx/refl.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "StaticString.hpp"
+#include <algorithm>
 #include <cstddef>
 #include <string_view>
 
@@ -14,24 +16,49 @@
 namespace rx {
 namespace detail {
 struct AnyStructFieldQuery {
-  template <typename T> constexpr operator T &&();
+  template <typename T> constexpr operator T();
 };
 
-template <typename StructT, std::size_t N = 1, std::size_t LastValidCount = 0>
+// clang 21 crashes with concept
+template <typename, typename, typename = void>
+struct IsValidFieldCountImpl : std::false_type {};
+template <typename StructT, std::size_t... I>
+struct IsValidFieldCountImpl<
+    StructT, std::index_sequence<I...>,
+    std::void_t<decltype(StructT{(I, AnyStructFieldQuery{})...})>>
+    : std::true_type {};
+template <typename StructT, std::size_t I>
+static constexpr bool IsValidFieldCount =
+    IsValidFieldCountImpl<StructT,
+                          decltype(std::make_index_sequence<I>{})>::value;
+
+template <typename StructT, std::size_t Min = 1,
+          std::size_t Max = std::min<std::size_t>(sizeof(StructT), 128),
+          std::size_t Mid = (Max - Min) / 2>
+struct CalcFieldCount;
+
+template <typename StructT, std::size_t Min, std::size_t Max, std::size_t Mid>
+  requires(Mid < Max && IsValidFieldCount<StructT, Mid>)
+struct CalcFieldCount<StructT, Min, Max, Mid>
+    : CalcFieldCount<StructT, Mid + 1, Max, (Mid + 1 + Max) / 2> {};
+
+template <typename StructT, std::size_t Min, std::size_t Max, std::size_t Mid>
+  requires(Mid < Max && !IsValidFieldCount<StructT, Mid>)
+struct CalcFieldCount<StructT, Min, Max, Mid>
+    : CalcFieldCount<StructT, Min, Mid, (Min + Mid) / 2> {};
+
+template <typename StructT, std::size_t Min, std::size_t Max, std::size_t Mid>
+  requires(Mid >= Max)
+struct CalcFieldCount<StructT, Min, Max, Mid> {
+  static constexpr auto count = Min == 0                          ? 0
+                                : IsValidFieldCount<StructT, Min> ? Min
+                                                                  : Min - 1;
+};
+
+template <typename StructT>
   requires std::is_class_v<StructT>
 constexpr auto calcFieldCount() {
-
-  auto isValidFieldCount = []<std::size_t... I>(std::index_sequence<I...>) {
-    return requires { StructT(((I, AnyStructFieldQuery{}))...); };
-  };
-
-  if constexpr (isValidFieldCount(std::make_index_sequence<N>())) {
-    return calcFieldCount<StructT, N + 1, N>();
-  } else if constexpr (sizeof(StructT) <= N || LastValidCount > 0) {
-    return LastValidCount;
-  } else {
-    return calcFieldCount<StructT, N + 1, LastValidCount>();
-  }
+  return CalcFieldCount<StructT>::count;
 }
 
 consteval std::string_view unwrapName(std::string_view prefix,
@@ -95,38 +122,45 @@ constexpr bool isField<TypeT(BaseT::*)> = true;
 
 } // namespace detail
 
-template <auto &&V> consteval auto getNameOf() {
-  std::string_view prefix;
+template <auto &&V> constexpr auto getNameOf() {
+  constexpr std::string_view prefix =
 #ifdef _MSC_VER
-  prefix = "getNameOf<";
+      "getNameOf<";
 #else
-  prefix = "V = ";
+      "V = ";
 #endif
-  return detail::unwrapName(prefix, RX_PRETTY_FUNCTION, true);
+  constexpr auto name = detail::unwrapName(prefix, RX_PRETTY_FUNCTION, true);
+  static constexpr auto result = rx::StaticString<name.size() + 1>{name};
+  return std::string_view{result};
 }
 
 template <auto V>
   requires(detail::isField<decltype(V)> ||
            std::is_enum_v<std::remove_cvref_t<decltype(V)>> ||
            std::is_pointer_v<std::remove_cvref_t<decltype(V)>>)
-consteval auto getNameOf() {
-  std::string_view prefix;
+constexpr auto getNameOf() {
+  constexpr std::string_view prefix =
 #ifdef _MSC_VER
-  prefix = "getNameOf<";
+      "getNameOf<";
 #else
-  prefix = "V = ";
+      "V = ";
 #endif
-  return detail::unwrapName(prefix, RX_PRETTY_FUNCTION, true);
+
+  constexpr auto name = detail::unwrapName(prefix, RX_PRETTY_FUNCTION, true);
+  static constexpr auto result = rx::StaticString<name.size() + 1>{name};
+  return std::string_view{result};
 }
 
-template <typename T> consteval auto getNameOf() {
-  std::string_view prefix;
+template <typename T> constexpr auto getNameOf() {
+  constexpr std::string_view prefix =
 #ifdef _MSC_VER
-  prefix = "getNameOf<";
+      "getNameOf<";
 #else
-  prefix = "T = ";
+      "T = ";
 #endif
-  return detail::unwrapName(prefix, RX_PRETTY_FUNCTION, false);
+  constexpr auto name = detail::unwrapName(prefix, RX_PRETTY_FUNCTION, false);
+  static constexpr auto result = rx::StaticString<name.size() + 1>{name};
+  return std::string_view{result};
 }
 
 namespace detail {