Add field set util to library

src/lib/library.cpp

@@ -1,2 +1,3 @@
 export module larra.library;
 export import larra.library.jid;
+export import larra.library.utils;

src/lib/utils.cpp

@@ -0,0 +1,99 @@
+module;
+#include <boost/pfr.hpp>
+export module larra.library.utils;
+import std;
+import utempl;
+
+namespace larra::xmpp::utils {
+
+template <typename T, typename... Fs>
+struct FieldDescription {
+  utempl::Tuple<Fs...> tuple;
+
+  template <typename R>
+  constexpr auto GetType(R(T::* ptr)) -> R;
+
+  template <std::size_t I, typename Self, typename Value>
+  constexpr auto With(Self&& self, Value&& value) const
+    requires([] {
+      if constexpr(I < sizeof...(Fs)) {
+        return std::is_constructible_v<decltype(GetType(Get<I>(tuple))), decltype(value)>;
+      };
+      return false;
+    }())
+
+  {
+    return [&](auto... is) -> T {
+      return {[&] -> decltype(auto) {
+        if constexpr(*is == I) {
+          return std::forward<Value>(value);
+        } else {
+          return std::forward_like<Self>(self.*Get<*is>(this->tuple));
+        };
+      }()...};
+    } | utempl::kSeq<sizeof...(Fs)>;
+  };
+
+  template <typename Self, typename Value, typename Type>
+  constexpr auto With(Type(T::* ptr), Self&& self, Value&& value) const
+    requires std::is_constructible_v<Type, decltype(value)>
+  {
+    return utempl::Unpack(this->tuple, [&](auto... fs) -> T {
+      return {[&] {
+        if constexpr(std::is_same_v<decltype(fs), decltype(ptr)>) {
+          if(fs == ptr) {
+            return std::forward<Value>(value);
+          };
+        };
+        return std::forward_like<Self>(self.*fs);
+      }()...};
+    });
+  };
+};
+
+template <typename T, typename... Fs>
+consteval auto CreateFieldsDescriptionHelper(Fs&&... fs) -> FieldDescription<T, std::decay_t<Fs>...> {
+  return {.tuple = {std::forward<Fs>(fs)...}};
+};
+
+export template <typename T, typename... Rs>
+consteval auto CreateFieldsDescription(Rs(T::*... ptr)) {
+  return [&](auto... is) {
+    return CreateFieldsDescriptionHelper<T>(ptr...);
+  } | utempl::kSeq<sizeof...(Rs)>;
+};
+
+export struct FieldSetHelper {
+  template <std::size_t I, typename Self, typename Value>
+  static constexpr auto With(Self&& self, Value&& value)
+    requires([] {
+      if constexpr(I < boost::pfr::tuple_size_v<std::decay_t<Self>>) {
+        return std::is_constructible_v<std::decay_t<decltype(boost::pfr::get<I>(std::declval<Self&>()))>, decltype(value)>;
+      };
+      return false;
+    }())
+  {
+    using T = std::decay_t<Self>;
+    return [&](auto... is) -> T {
+      return {[&] -> decltype(auto) {
+        if constexpr(I == *is) {
+          return std::forward<Value>(value);
+        } else {
+          return std::forward_like<Self>(boost::pfr::get<*is>(self));
+        };
+      }()...};
+    } | utempl::kSeq<boost::pfr::tuple_size_v<T>>;
+  };
+
+  template <utempl::ConstexprString FieldName, typename Self, typename Value>
+  static constexpr auto With(Self&& self, Value&& value) -> decltype(With<[] {
+    auto names = boost::pfr::names_as_array<std::decay_t<Self>>();
+    return std::ranges::find(names, static_cast<std::string_view>(FieldName)) - names.begin();
+  }()>(std::forward<Self>(self), std::forward<Value>(value))) {
+    constexpr auto names = boost::pfr::names_as_array<std::decay_t<Self>>();
+    constexpr auto id = std::ranges::find(names, static_cast<std::string_view>(FieldName)) - names.begin();
+    return With<id>(std::forward<Self>(self), std::forward<Value>(value));
+  };
+};
+
+}  // namespace larra::xmpp::utils

tests/set.cpp

@@ -0,0 +1,88 @@
+module;
+#include <gtest/gtest.h>
+export module tests.set;
+import larra.library.utils;
+
+namespace larra::xmpp {
+
+struct SomeStruct {
+  std::string field1;
+  float field2 = 1.f;
+  template <typename Self>
+  auto Field1(this Self&& self, std::string field1) -> decltype(auto) {
+    return utils::FieldSetHelper::With<0>(std::forward<Self>(self), std::move(field1));
+  }
+  template <typename Self>
+  auto Field2(this Self&& self, float field2) -> decltype(auto) {
+    return utils::FieldSetHelper::With<"field2">(std::forward<Self>(self), std::move(field2));
+  }
+};
+
+TEST(Set, Basic) {
+  auto obj = SomeStruct{}.Field1("Hello").Field2(.0f);
+  EXPECT_EQ(obj.field1, "Hello");
+  EXPECT_EQ(obj.field2, .0f);
+}
+
+struct SomeStruct2 {
+  SomeStruct2(const SomeStruct2&) = delete;
+  SomeStruct2() = default;
+  SomeStruct2(SomeStruct2&&) = default;
+};
+
+struct SomeStruct3 {
+  SomeStruct2 field1;
+  SomeStruct2 field2;
+  template <typename Self>
+  auto Field1(this Self&& self, SomeStruct2 field1) -> decltype(auto) {
+    return utils::FieldSetHelper::With<0>(std::forward<Self>(self), std::move(field1));
+  }
+  template <typename Self>
+  auto Field2(this Self&& self, SomeStruct2 field2) -> decltype(auto) {
+    return utils::FieldSetHelper::With<"field2">(std::forward<Self>(self), std::move(field2));
+  }
+};
+
+TEST(Set, NonCopyable) {
+  auto obj = SomeStruct3{}.Field1({}).Field2({});
+}
+
+struct SomeStruct4 {
+  std::string field1;
+  float field2 = 1.f;
+  static constexpr auto kUtils = utils::CreateFieldsDescription(&SomeStruct4::field1, &SomeStruct4::field2);
+  template <typename Self>
+  auto Field1(this Self&& self, std::string field1) -> decltype(auto) {
+    return kUtils.With<0>(std::forward<Self>(self), std::move(field1));
+  }
+  template <typename Self>
+  auto Field2(this Self&& self, float field2) -> decltype(auto) {
+    return kUtils.With(&SomeStruct4::field2, std::forward<Self>(self), std::move(field2));
+  }
+};
+
+struct SomeStruct5 {
+  SomeStruct2 field1;
+  SomeStruct2 field2;
+  static constexpr auto kUtils = utils::CreateFieldsDescription(&SomeStruct5::field1, &SomeStruct5::field2);
+  template <typename Self>
+  auto Field1(this Self&& self, SomeStruct2 field1) -> decltype(auto) {
+    return kUtils.With<0>(std::forward<Self>(self), std::move(field1));
+  }
+  template <typename Self>
+  auto Field2(this Self&& self, SomeStruct2 field2) -> decltype(auto) {
+    return kUtils.With(&SomeStruct5::field2, std::forward<Self>(self), std::move(field2));
+  }
+};
+
+TEST(NonPfrSet, Basic) {
+  auto obj = SomeStruct4{}.Field1("Hello").Field2(.0f);
+  EXPECT_EQ(obj.field1, "Hello");
+  EXPECT_EQ(obj.field2, .0f);
+}
+
+TEST(NonPfrSet, NonCopyable) {
+  auto obj = SomeStruct5{}.Field1({}).Field2({});
+}
+
+}  // namespace larra::xmpp