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#pragma once
#include "constraints.hpp"
#include "concepts.hpp"
#include "accessor.hpp"
#include "field-status.hpp"
#include "compat/defs.hpp"
namespace floormat::entities::detail {
template<typename Obj, typename Type, typename Default, size_t I, typename... Fs> struct find_reader;
template<typename Obj, typename Type, typename Default, size_t I> struct find_reader<Obj, Type, Default, I> {
using type = Default;
static constexpr size_t index = I;
};
template<typename Obj, typename Type, typename Default, size_t I, typename F, typename... Fs>
struct find_reader<Obj, Type, Default, I, F, Fs...> {
using type = typename find_reader<Obj, Type, Default, I+1, Fs...>::type;
static constexpr size_t index = find_reader<Obj, Type, Default, I+1, Fs...>::index;
};
template<typename Obj, typename Type, typename Default, size_t I, typename F, typename... Fs>
requires FieldReader<F, Obj, Type>
struct find_reader<Obj, Type, Default, I, F, Fs...> { using type = F; static constexpr size_t index = I; };
} // namespace floormat::entities::detail
namespace floormat::entities {
constexpr auto constantly(const auto& x) noexcept {
return [x]<typename... Ts> (const Ts&...) constexpr -> const auto& { return x; };
}
template<typename Obj, typename Type> struct entity_field_base {};
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
struct entity_field : entity_field_base<Obj, Type> {
private:
static constexpr auto default_predicate = constantly(field_status::enabled);
static constexpr auto default_c_range = constantly(constraints::range<Type>{});
static constexpr auto default_c_length = constantly(constraints::max_length{size_t(-1)});
using default_predicate_t = std::decay_t<decltype(default_predicate)>;
using default_c_range_t = std::decay_t<decltype(default_c_range)>;
using default_c_length_t = std::decay_t<decltype(default_c_length)>;
using c_predicate = detail::find_reader<Obj, field_status, default_predicate_t, 0, Ts...>;
using c_range = detail::find_reader<Obj, constraints::range<Type>, default_c_range_t, 0, Ts...>;
using c_length = detail::find_reader<Obj, constraints::max_length, default_c_length_t, 0, Ts...>;
static constexpr size_t good_arguments =
unsigned(c_predicate::index != sizeof...(Ts)) +
unsigned(c_range::index != sizeof...(Ts)) +
unsigned(c_length::index != sizeof...(Ts));
static_assert(sizeof...(Ts) == good_arguments, "ignored arguments");
public:
using ObjectType = Obj;
using FieldType = Type;
using Reader = R;
using Writer = W;
using Predicate = typename c_predicate::type;
using Range = typename c_range::type;
using Length = typename c_length::type;
StringView name;
[[fm_no_unique_address]] R reader;
[[fm_no_unique_address]] W writer;
[[fm_no_unique_address]] Predicate predicate;
[[fm_no_unique_address]] Range range;
[[fm_no_unique_address]] Length length;
fm_DECLARE_DEFAULT_MOVE_COPY_ASSIGNMENTS(entity_field);
static constexpr decltype(auto) read(const R& reader, const Obj& x) { return detail::read_field<Obj, Type, R>::read(x, reader); }
static constexpr void write(const W& writer, Obj& x, Type v);
constexpr decltype(auto) read(const Obj& x) const { return read(reader, x); }
constexpr void write(Obj& x, Type value) const { write(writer, x, move(value)); }
static constexpr bool can_write = !std::is_same_v<std::nullptr_t, decltype(entity_field<Obj, Type, R, W, Ts...>::writer)>;
static constexpr field_status is_enabled(const Predicate & p, const Obj& x);
constexpr field_status is_enabled(const Obj& x) const { return is_enabled(predicate, x); }
static constexpr constraints::range<Type> get_range(const Range& r, const Obj& x);
constexpr constraints::range<Type> get_range(const Obj& x) const { return get_range(range, x); }
static constexpr constraints::max_length get_max_length(const Length& l, const Obj& x);
constexpr constraints::max_length get_max_length(const Obj& x) const { return get_max_length(length, x); }
constexpr entity_field(StringView name, R r, W w, Ts&&... ts) noexcept :
name{name}, reader{r}, writer{w},
predicate { std::get<c_predicate::index>(std::forward_as_tuple(ts..., default_predicate)) },
range { std::get<c_range::index> (std::forward_as_tuple(ts..., default_c_range)) },
length { std::get<c_length::index> (std::forward_as_tuple(ts..., default_c_length)) }
{}
constexpr erased_accessor erased() const;
};
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
constexpr void entity_field<Obj, Type, R, W, Ts...>::write(const W& writer, Obj& x, Type v)
{
static_assert(can_write); detail::write_field<Obj, Type, W>::write(x, writer, move(v));
}
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
constexpr erased_accessor entity_field<Obj, Type, R, W, Ts...>::erased() const
{
using reader_t = typename erased_accessor::reader_t;
using writer_t = typename erased_accessor::writer_t;
using predicate_t = typename erased_accessor::predicate_t;
using c_range_t = typename erased_accessor::c_range_t;
using c_length_t = typename erased_accessor::c_length_t;
constexpr auto obj_name = name_of<Obj>, field_name = name_of<Type>;
constexpr auto reader_fn = [](const void* obj, const reader_t* reader, void* value) {
const auto& obj_ = *static_cast<const Obj*>(obj);
const auto& reader_ = *static_cast<const R*>(reader);
auto& value_ = *static_cast<Type*>(value);
value_ = read(reader_, obj_);
};
constexpr auto writer_fn = [](void* obj, const writer_t* writer, void* value) {
auto& obj_ = *static_cast<Obj*>(obj);
const auto& writer_ = *static_cast<const W*>(writer);
Type value_ = move(*static_cast<Type*>(value));
write(writer_, obj_, move(value_));
};
constexpr auto predicate_fn = [](const void* obj, const predicate_t* predicate) {
const auto& obj_ = *static_cast<const Obj*>(obj);
const auto& predicate_ = *static_cast<const Predicate*>(predicate);
return is_enabled(predicate_, obj_);
};
constexpr auto writer_stub_fn = [](void*, const writer_t*, void*) {
fm_abort("no writer for this accessor");
};
constexpr bool has_writer = !std::is_same_v<std::decay_t<decltype(writer)>, std::nullptr_t>;
constexpr auto c_range_fn = [](const void* obj, const c_range_t* reader) -> erased_constraints::range {
return get_range(*static_cast<const Range*>(reader), *static_cast<const Obj*>(obj));
};
constexpr auto c_length_fn = [](const void* obj, const c_length_t* reader) -> erased_constraints::max_length {
return get_max_length(*static_cast<const Length*>(reader), *static_cast<const Obj*>(obj));
};
return erased_accessor {
(void*)&reader, has_writer ? (void*)&writer : nullptr,
(void*)&predicate,
(void*)&range, (void*)&length,
name, obj_name, field_name,
reader_fn, has_writer ? writer_fn : writer_stub_fn,
predicate_fn,
c_range_fn, c_length_fn,
};
}
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
constexpr field_status entity_field<Obj, Type, R, W, Ts...>::is_enabled(const Predicate& p, const Obj& x)
{ return detail::read_field<Obj, field_status, Predicate>::read(x, p); }
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
constexpr constraints::range<Type> entity_field<Obj, Type, R, W, Ts...>::get_range(const Range& r, const Obj& x)
{ return detail::read_field<Obj, constraints::range<Type>, Range>::read(x, r); }
template<typename Obj, typename Type, FieldReader<Obj, Type> R, FieldWriter<Obj, Type> W, typename... Ts>
constexpr constraints::max_length entity_field<Obj, Type, R, W, Ts...>::get_max_length(const Length& l, const Obj& x)
{ return detail::read_field<Obj, constraints::max_length , Length>::read(x, l); }
} // namespace floormat::entities
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