Merge pull request #10 from contour-terminal/improvement/Lightweight-related

Some additions and tweaks

Author: christianparpart

include/reflection-cpp/reflection.hpp

@@ -202,7 +202,7 @@ inline constexpr decltype(auto) ToTuple(T&& t) noexcept
 {
     if constexpr (N == 0)
         return std::tuple {};
-    //clang-format off
+    // clang-format off
     else if constexpr (N == 1)
     {
         auto& [p0] = t;
@@ -453,7 +453,7 @@ inline constexpr decltype(auto) ToTuple(T&& t) noexcept
         auto& [p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11, p12, p13, p14, p15, p16, p17, p18, p19, p20, p21, p22, p23, p24, p25, p26, p27, p28, p29, p30, p31, p32, p33, p34, p35, p36, p37, p38, p39, p40, p41, p42, p43, p44, p45, p46, p47, p48, p49] = t;
         return std::tie(p0, p1, p2, p3, p4, p5, p6, p7, p8, p9, p10, p11, p12, p13, p14, p15, p16, p17, p18, p19, p20, p21, p22, p23, p24, p25, p26, p27, p28, p29, p30, p31, p32, p33, p34, p35, p36, p37, p38, p39, p40, p41, p42, p43, p44, p45, p46, p47, p48, p49);
     }
-    //clang-format on
+    // clang-format on
 }
 
 template <class T>
@@ -683,12 +683,64 @@ consteval auto GetName()
 }
 
 template <typename Object, typename Callable>
-decltype(auto) CallOnMembers(Object const& object, Callable&& callable)
+void CallOnMembers(Object const& object, Callable&& callable)
 {
     template_for<0, Reflection::CountMembers<Object>>(
         [&]<auto I>() { callable(Reflection::MemberNameOf<I, Object>, std::get<I>(Reflection::ToTuple(object))); });
 }
 
+template <typename Object, typename Callable>
+void CallOnMembers(Object& object, Callable&& callable)
+{
+    template_for<0, Reflection::CountMembers<Object>>(
+        [&]<auto I>() { callable(Reflection::MemberNameOf<I, Object>, std::get<I>(Reflection::ToTuple(object))); });
+}
+
+/// Folds over the members of a type without an object of it.
+///
+/// @param initialValue The initial value to fold with
+/// @param callable     The callable to fold with. The parameters are the member name,
+///                     the member's default value and the current result of the fold.
+///
+/// @return The result of the fold
+template <typename Object, typename Callable, typename ResultType>
+constexpr ResultType FoldMembers(ResultType initialValue, Callable const& callable)
+{
+    // clang-format off
+    ResultType result = initialValue;
+    template_for<0, Reflection::CountMembers<Object>>(
+        [&]<size_t I>() {
+            result = callable(Reflection::MemberNameOf<I, Object>,
+                              std::get<I>(Reflection::ToTuple(Object {})),
+                              result);
+        }
+    );
+    // clang-format on
+    return result;
+}
+
+/// Folds over the members of an object
+///
+/// @param object       The object to fold over
+/// @param initialValue The initial value to fold with
+/// @param callable     The callable to fold with. The parameters are the member name,
+///                     the member value and the current result of the fold.
+///
+/// @return The result of the fold
+template <typename Object, typename Callable, typename ResultType>
+constexpr ResultType FoldMembers(Object const& object, ResultType initialValue, Callable const& callable)
+{
+    // clang-format off
+    ResultType result = initialValue;
+    template_for<0, Reflection::CountMembers<Object>>([&]<size_t I>() {
+        result = callable(Reflection::MemberNameOf<I, Object>, 
+                          std::get<I>(Reflection::ToTuple(object)), 
+                          result);
+    });
+    return result;
+    // clang-format on
+}
+
 template <typename Object>
 std::string Inspect(Object const& object)
 {

test-reflection-cpp.cpp

@@ -59,7 +59,6 @@ TEST_CASE("vector", "[reflection]")
     CHECK(result == R"(name="John Doe" email="[email protected]" age=42
 name="John Doe" email="[email protected]" age=43
 )");
-    //clang-format on
 }
 
 TEST_CASE("nested", "[reflection]")
@@ -68,3 +67,29 @@ TEST_CASE("nested", "[reflection]")
     auto const result = Reflection::Inspect(ts);
     CHECK(result == R"(a=1 b=2 c=3 d="hello" e={name="John Doe" email="[email protected]" age=42})");
 }
+
+TEST_CASE("FoldMembers.type", "[reflection]")
+{
+    // clang-format off
+    auto const result = Reflection::FoldMembers<TestStruct>(0, [](auto&& /*name*/, auto&& /*value*/, auto&& result) {
+        return result + 1;
+    });
+    // clang-format on
+    CHECK(result == 5);
+}
+
+struct S
+{
+    int a {};
+    int b {};
+    int c {};
+};
+
+TEST_CASE("FoldMembers.value", "[reflection]")
+{
+    auto const s = S { 1, 2, 3 };
+    auto const result = Reflection::FoldMembers(
+        s, 0, [](auto&& /*name*/, auto&& memberValue, auto&& accum) { return accum + memberValue; });
+
+    CHECK(result == 6);
+}