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#pragma once
// variant.hpp - A single value, multiple type container. Better than boost's.
//
// Copyright © 2012 Ben Longbons <b.r.longbons@gmail.com>
//
// This file is part of The Mana World (Athena server)
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include <type_traits>
#include <cstdint>
#include <cstddef>
#include <utility>
#include "union.hpp"
#include "void.hpp"
#include "fwd.hpp"
namespace tmwa
{
namespace sexpr
{
#define JOIN(a, b) a##b
#define WITH_VAR(ty, var, expr) \
for (bool JOIN(var, _guard) = true; JOIN(var, _guard); ) \
for (ty var = expr; JOIN(var, _guard); JOIN(var, _guard) = false)
#define MATCH(expr) \
WITH_VAR(auto&&, _match_var, expr) \
switch (tmwa::sexpr::VariantFriend::get_state(_match_var))
#define CASE(ty, var) \
break; \
case tmwa::sexpr::VariantFriend::get_state_for<ty, decltype(_match_var)>(): \
WITH_VAR(ty, var, tmwa::sexpr::VariantFriend::unchecked_get<ty>(_match_var))
template<class... T>
class Variant
{
static_assert(sizeof...(T), "A variant must not be empty");
};
template<class D, class... T>
class Variant<D, T...>
{
constexpr static size_t state_count = 1 + sizeof...(T);
// simplify things immensely
friend class VariantFriend;
typedef Union<D, T...> DataType;
DataType data;
size_t state;
void do_destruct();
template<class C, class... A>
void do_construct(A&&... a);
public:
Variant();
~Variant();
void reset();
template<class C, class... A>
void emplace(A&&... a);
Variant(const Variant& r);
Variant(Variant&& r);
Variant& operator = (const Variant& r);
Variant& operator = (Variant&& r);
template<class E>
Variant(E e)
{
do_construct<E, E>(std::move(e));
}
template<class E>
Variant& operator = (E e)
{
emplace<E, E>(std::move(e));
return *this;
}
// use these ONLY if only one type makes sense
// otherwise use apply
template<class E>
bool is() const;
template<class E>
E *get_if();
template<class E>
const E *get_if() const;
};
template<class R, class F>
void apply(R& r, F&& f);
template<class R, class F, class V1, class... V>
void apply(R& r, F&& f, V1&& v1, V&&... v);
template<class F, class... V>
void apply(Void&& r, F&& f, V&&... v);
} // namespace sexpr
using sexpr::Variant;
} // namespace tmwa
#include "variant.tcc"
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