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457 lines (389 loc) · 14.7 KB
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/******************************************************************************\
* ___ __ *
* /\_ \ __/\ \ *
* \//\ \ /\_\ \ \____ ___ _____ _____ __ *
* \ \ \ \/\ \ \ '__`\ /'___\/\ '__`\/\ '__`\ /'__`\ *
* \_\ \_\ \ \ \ \L\ \/\ \__/\ \ \L\ \ \ \L\ \/\ \L\.\_ *
* /\____\\ \_\ \_,__/\ \____\\ \ ,__/\ \ ,__/\ \__/.\_\ *
* \/____/ \/_/\/___/ \/____/ \ \ \/ \ \ \/ \/__/\/_/ *
* \ \_\ \ \_\ *
* \/_/ \/_/ *
* *
* Copyright (C) 2011-2013 *
* Dominik Charousset <dominik.charousset@haw-hamburg.de> *
* *
* This file is part of libcppa. *
* libcppa is free software: you can redistribute it and/or modify it under *
* the terms of the GNU Lesser General Public License as published by the *
* Free Software Foundation; either version 2.1 of the License, *
* or (at your option) any later version. *
* *
* libcppa 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 Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with libcppa. If not, see <http://www.gnu.org/licenses/>. *
\******************************************************************************/
#ifndef OPTIONAL_VARIANT_HPP
#define OPTIONAL_VARIANT_HPP
#include <ostream>
#include <stdexcept>
#include <type_traits>
#include "cppa/none.hpp"
#include "cppa/unit.hpp"
#include "cppa/optional.hpp"
#include "cppa/skip_message.hpp"
#include "cppa/util/type_list.hpp"
#include "cppa/util/type_traits.hpp"
#include "cppa/detail/optional_variant_data.hpp"
#define CPPA_OPTIONAL_VARIANT_CASE(x) \
case x: return do_visit(from, visitor, \
make_bool_token<void_pos == x >(), \
make_int_token< x >()) \
namespace cppa {
template<int Value>
constexpr std::integral_constant<int, Value> make_int_token() { return {}; }
template<bool Value>
constexpr std::integral_constant<bool, Value> make_bool_token() { return {}; }
template<typename T>
struct optional_variant_copy_helper {
T& lhs;
optional_variant_copy_helper(T& lhs_ref) : lhs(lhs_ref) { }
template<typename U>
inline void operator()(const U& rhs) const {
lhs = rhs;
}
inline void operator()() const {
lhs = unit;
}
inline void operator()(const none_t&) const {
lhs = none;
}
};
template<typename T>
struct optional_variant_move_helper {
T& lhs;
optional_variant_move_helper(T& lhs_ref) : lhs(lhs_ref) { }
template<typename U>
inline void operator()(U& rhs) const {
lhs = std::move(rhs);
}
inline void operator()() const {
lhs = unit;
}
inline void operator()(const none_t&) const {
lhs = none;
}
};
template<typename... Ts>
class optional_variant;
template<typename T>
struct is_optional_variant {
static constexpr bool value = false;
};
template<typename... Ts>
struct is_optional_variant<optional_variant<Ts...>> {
static constexpr bool value = true;
};
/**
* @brief A optional_variant is either invalid or holds
a value of one of the types <tt>Ts</tt>.
*/
template<typename... Ts>
class optional_variant {
public:
typedef util::type_list<Ts...> types;
static constexpr int void_pos = util::tl_find<types, void>::value;
/**
* @brief Checks whether this objects holds a value of type @p T.
*/
template<typename T>
inline bool is() const {
return m_type != -1 && m_type == util::tl_find<types, T>::value;
}
template<typename U>
optional_variant& operator=(U&& arg) {
destroy_data();
set(std::forward<U>(arg));
return *this;
}
optional_variant& operator=(const optional_variant& other) {
destroy_data();
optional_variant_copy_helper<optional_variant> helper{*this};
other.apply(helper);
return *this;
}
optional_variant& operator=(optional_variant&& other) {
destroy_data();
optional_variant_move_helper<optional_variant> helper{*this};
other.apply(helper);
return *this;
}
optional_variant() : m_type(-1) { }
template<typename U>
optional_variant(U&& arg) {
set(std::forward<U>(arg));
}
optional_variant(const optional_variant& other) : m_type(-1) {
optional_variant_copy_helper<optional_variant> helper{*this};
other.apply(helper);
}
optional_variant(optional_variant&& other) : m_type(-1) {
optional_variant_move_helper<optional_variant> helper{*this};
other.apply(helper);
}
~optional_variant() {
destroy_data();
}
/**
* @brief Checks whether this optional_variant is valid.
*/
inline explicit operator bool() const {
return m_type != -1;
}
/**
* @brief Checks whether this optional_variant is invalid.
*/
inline bool operator!() const {
return m_type == -1;
}
/** @cond PRIVATE */
template<int Pos>
inline const typename util::tl_at<types, Pos>::type&
get(std::integral_constant<int, Pos> token,
typename std::enable_if<Pos < sizeof...(Ts) && Pos != void_pos>::type* = nullptr) const {
return m_data.get(token);
}
template<int Pos>
inline void get(std::integral_constant<int, Pos>,
typename std::enable_if<Pos >= sizeof...(Ts) || Pos == void_pos>::type* = nullptr) const { }
template<int Pos>
inline typename util::tl_at<types, Pos>::type&
get(std::integral_constant<int, Pos> token,
typename std::enable_if<Pos < sizeof...(Ts) && Pos != void_pos>::type* = nullptr) {
return m_data.get(token);
}
template<typename Visitor>
auto apply(Visitor& visitor) const -> decltype(visitor(none_t{})) {
return do_apply(*this, visitor);
}
template<typename Visitor>
auto apply(Visitor& visitor) -> decltype(visitor(none_t{})) {
return do_apply(*this, visitor);
}
/** @endcond */
private:
template<typename Self, typename Visitor, int Pos>
static auto do_visit(Self& from,
const Visitor& visitor,
std::integral_constant<bool, false> /* is_not_void */,
std::integral_constant<int, Pos> token,
typename std::enable_if<Pos < sizeof...(Ts)>::type* = nullptr)
-> decltype(visitor(none_t{})) {
return visitor(from.get(token));
}
template<typename Self, typename Visitor, int Pos>
static auto do_visit(Self&,
const Visitor& visitor,
std::integral_constant<bool, true> /* is_void */,
std::integral_constant<int, Pos>,
typename std::enable_if<Pos < sizeof...(Ts)>::type* = nullptr)
-> decltype(visitor(none_t{})) {
return visitor();
}
template<typename Self, typename Visitor, int Pos>
static auto do_visit(Self&,
const Visitor& visitor,
std::integral_constant<bool, false>,
std::integral_constant<int, Pos>,
typename std::enable_if<Pos >= sizeof...(Ts)>::type* = nullptr)
-> decltype(visitor(none_t{})) {
// this is not the function you are looking for
throw std::runtime_error("invalid type found");
}
template<typename Self, typename Visitor>
static auto do_apply(Self& from, Visitor& visitor) -> decltype(visitor(none_t{})) {
switch (from.m_type) {
default: throw std::runtime_error("invalid type found");
case -1: return visitor(none_t{});
CPPA_OPTIONAL_VARIANT_CASE(0);
CPPA_OPTIONAL_VARIANT_CASE(1);
CPPA_OPTIONAL_VARIANT_CASE(2);
CPPA_OPTIONAL_VARIANT_CASE(3);
CPPA_OPTIONAL_VARIANT_CASE(4);
CPPA_OPTIONAL_VARIANT_CASE(5);
CPPA_OPTIONAL_VARIANT_CASE(6);
CPPA_OPTIONAL_VARIANT_CASE(7);
CPPA_OPTIONAL_VARIANT_CASE(8);
CPPA_OPTIONAL_VARIANT_CASE(9);
}
}
inline void destroy_data() {
detail::optional_variant_data_destructor f;
apply(f);
}
template<typename U>
typename std::enable_if<
!std::is_same<typename util::rm_const_and_ref<U>::type, none_t>::value
&& !is_optional_variant<typename util::rm_const_and_ref<U>::type>::value
&& !is_optional<typename util::rm_const_and_ref<U>::type>::value
>::type
set(U&& arg) {
typedef typename util::rm_const_and_ref<U>::type stripped_type;
typedef typename detail::unlift_void<stripped_type>::type type;
static constexpr int type_id = util::tl_find<types, type>::value;
static_assert(type_id != -1, "invalid type");
m_type = type_id;
auto& ref = m_data.get(make_int_token<type_id>());
new (&ref) stripped_type (std::forward<U>(arg));
}
inline void set(const optional_variant& other) {
optional_variant_copy_helper<optional_variant> helper{*this};
other.apply(helper);
}
inline void set(optional_variant&& other) {
optional_variant_move_helper<optional_variant> helper{*this};
other.apply(helper);
}
template<typename T>
inline void set(const optional<T>& arg) {
if (arg) set(*arg);
else set(none);
}
template<typename T>
inline void set(optional<T>&& arg) {
if (arg) set(std::move(*arg));
else set(none);
}
inline void set(const none_t&) { m_type = -1; }
int m_type;
detail::optional_variant_data<typename detail::lift_void<Ts>::type...> m_data;
};
/**
* @relates optional_variant
*/
template<typename T, typename... Us>
const T& get(const optional_variant<Us...>& value) {
std::integral_constant<int, util::tl_find<util::type_list<Us...>, T>::value> token;
return value.get(token);
}
/**
* @relates optional_variant
*/
template<typename T, typename... Us>
T& get_ref(optional_variant<Us...>& value) {
std::integral_constant<int, util::tl_find<util::type_list<Us...>, T>::value> token;
return value.get(token);
}
/**
* @relates optional_variant
*/
template<typename Visitor, typename... Ts>
auto apply_visitor(Visitor& visitor, const optional_variant<Ts...>& data) -> decltype(visitor(none_t{})) {
return data.apply(visitor);
}
/**
* @relates optional_variant
*/
template<typename Visitor, typename... Ts>
auto apply_visitor(const Visitor& visitor, const optional_variant<Ts...>& data) -> decltype(visitor(none_t{})) {
return data.apply(visitor);
}
/**
* @relates optional_variant
*/
template<typename Visitor, typename... Ts>
auto apply_visitor(Visitor& visitor, optional_variant<Ts...>& data) -> decltype(visitor(none_t{})) {
return data.apply(visitor);
}
/**
* @relates optional_variant
*/
template<typename Visitor, typename... Ts>
auto apply_visitor(const Visitor& visitor, optional_variant<Ts...>& data) -> decltype(visitor(none_t{})) {
return data.apply(visitor);
}
template<typename T>
struct optional_variant_from_type_list;
template<typename... Ts>
struct optional_variant_from_type_list<util::type_list<Ts...>> {
typedef optional_variant<Ts...> type;
};
namespace detail {
template<typename T>
struct optional_variant_cmp_helper {
const T& lhs;
optional_variant_cmp_helper(const T& value) : lhs{value} { }
// variant is comparable
template<typename U>
typename std::enable_if<util::is_comparable<T, U>::value, bool>::type
operator()(const U& rhs) const { return lhs == rhs; }
// variant is not comparable
template<typename U>
typename std::enable_if<!util::is_comparable<T, U>::value, bool>::type
operator()(const U&) const { return false; }
// variant is void
bool operator()() const { return false; }
// variant is undefined
bool operator()(const none_t&) const { return false; }
};
} // namespace detail
/**
* @relates optional_variant
*/
template<typename T, typename... Ts>
bool operator==(const T& lhs, const optional_variant<Ts...>& rhs) {
return apply_visitor(detail::optional_variant_cmp_helper<T>{lhs}, rhs);
}
/**
* @relates optional_variant
*/
template<typename T, typename... Ts>
bool operator==(const optional_variant<Ts...>& lhs, const T& rhs) {
return rhs == lhs;
}
namespace detail {
struct optional_variant_ostream_helper {
std::ostream& lhs;
inline optional_variant_ostream_helper(std::ostream& os) : lhs(os) { }
template<typename T>
std::ostream& operator()(const T& value) const {
return lhs << value;
}
inline std::ostream& operator()(const none_t&) const {
return lhs << "<none>";
}
inline std::ostream& operator()() const {
return lhs << "<void>";
}
template<typename T0>
std::ostream& operator()(const cow_tuple<T0>& value) const {
return lhs << get<0>(value);
}
template<typename T0, typename T1, typename... Ts>
std::ostream& operator()(const cow_tuple<T0, T1, Ts...>& value) const {
lhs << get<0>(value) << " ";
return (*this)(value.drop_left());
}
};
} // namespace detail
/**
* @relates optional_variant
*/
template<typename T0, typename... Ts>
std::ostream& operator<<(std::ostream& lhs, const optional_variant<T0, Ts...>& rhs) {
return apply_visitor(detail::optional_variant_ostream_helper{lhs}, rhs);
}
template<typename T, typename... Ts>
optional_variant<T, typename util::rm_const_and_ref<Ts>::type...>
make_optional_variant(T value, Ts&&... args) {
return {std::move(value), std::forward<Ts>(args)...};
}
template<typename... Ts>
inline optional_variant<Ts...> make_optional_variant(optional_variant<Ts...> value) {
return value;
}
} // namespace cppa
#endif // OPTIONAL_VARIANT_HPP
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