diff options
Diffstat (limited to 'entity')
| -rw-r--r-- | entity/accessor.hpp | 1 | ||||
| -rw-r--r-- | entity/entity.hpp | 9 |
2 files changed, 9 insertions, 1 deletions
diff --git a/entity/accessor.hpp b/entity/accessor.hpp index 9b836420..a097afd4 100644 --- a/entity/accessor.hpp +++ b/entity/accessor.hpp @@ -40,6 +40,7 @@ struct erased_accessor final { template<typename Obj, typename FieldType> requires std::is_default_constructible_v<FieldType> FieldType read(const Obj& x) const noexcept; template<typename Obj, typename FieldType> void read(const Obj& x, FieldType& value) const noexcept; template<typename Obj, typename FieldType> void write(Obj& x, move_qualified<FieldType> value) const noexcept; + constexpr bool can_write() const noexcept { return writer != nullptr; } }; template<typename T, typename FieldType> diff --git a/entity/entity.hpp b/entity/entity.hpp index 4eca858e..30c75c15 100644 --- a/entity/entity.hpp +++ b/entity/entity.hpp @@ -56,7 +56,8 @@ template<typename F, typename T, typename FieldType> concept FieldWriter = requires { requires FieldWriter_memfn<F, T, FieldType> || FieldWriter_ptr<F, T, FieldType> || - FieldWriter_function<F, T, FieldType>; + FieldWriter_function<F, T, FieldType> || + std::same_as<F, std::nullptr_t>; }; namespace detail { @@ -100,6 +101,11 @@ struct write_field<Obj, Type, fu2::function_base<IsOwning, IsCopyable, Capacity, template<typename F> static constexpr void write(Obj& x, F&& fun, move_qualified<Type> value) { fun(x, value); } }; +template<typename Obj, typename FieldType> +struct write_field<Obj, FieldType, std::nullptr_t> { + static constexpr void write(Obj&, std::nullptr_t, move_qualified<FieldType>) { fm_abort("no writing for this accessor"); } +}; + template<typename F, typename Tuple, std::size_t N> requires std::invocable<F, decltype(std::get<N>(std::declval<Tuple>()))> constexpr CORRADE_ALWAYS_INLINE void visit_tuple(F&& fun, Tuple&& tuple) @@ -152,6 +158,7 @@ struct entity_field : entity_field_base<Obj, Type> { static constexpr void write(const W& writer, Obj& x, move_qualified<Type> v) { detail::write_field<Obj, Type, W>::write(x, writer, v); } constexpr decltype(auto) read(const Obj& x) const { return read(reader, x); } constexpr void write(Obj& x, move_qualified<Type> value) const { write(writer, x, value); } + static constexpr bool can_write = !std::is_same_v<std::nullptr_t, decltype(entity_field<Obj, Type, R, W>::writer)>; constexpr entity_field(StringView name, R r, W w) noexcept : name{name}, reader{r}, writer{w} {} constexpr erased_accessor erased() const; }; |