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Copy pathoptional.hpp
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347 lines (269 loc) · 8.69 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 CPPA_OPTION_HPP
#define CPPA_OPTION_HPP
#include <new>
#include <utility>
#include "cppa/none.hpp"
#include "cppa/unit.hpp"
#include "cppa/config.hpp"
namespace cppa {
/**
* @brief Represents an optional value of @p T.
*/
template<typename T>
class optional {
public:
/**
* @brief Typdef for @p T.
*/
typedef T type;
/* *
* @brief Default constructor.
* @post <tt>valid() == false</tt>
*/
//optional() : m_valid(false) { }
/**
* @post <tt>valid() == false</tt>
*/
optional(const none_t& = none) : m_valid(false) { }
/**
* @brief Creates an @p option from @p value.
* @post <tt>valid() == true</tt>
*/
optional(T value) : m_valid(false) { cr(std::move(value)); }
optional(const optional& other) : m_valid(false) {
if (other.m_valid) cr(other.m_value);
}
optional(optional&& other) : m_valid(false) {
if (other.m_valid) cr(std::move(other.m_value));
}
~optional() { destroy(); }
optional& operator=(const optional& other) {
if (m_valid) {
if (other.m_valid) m_value = other.m_value;
else destroy();
}
else if (other.m_valid) {
cr(other.m_value);
}
return *this;
}
optional& operator=(optional&& other) {
if (m_valid) {
if (other.m_valid) m_value = std::move(other.m_value);
else destroy();
}
else if (other.m_valid) {
cr(std::move(other.m_value));
}
return *this;
}
/**
* @brief Returns @p true if this @p option has a valid value;
* otherwise @p false.
*/
inline bool valid() const { return m_valid; }
/**
* @brief Returns <tt>!valid()</tt>.
*/
inline bool empty() const { return !m_valid; }
/**
* @copydoc valid()
*/
inline explicit operator bool() const { return valid(); }
/**
* @brief Returns <tt>!valid()</tt>.
*/
inline bool operator!() const { return empty(); }
inline bool operator==(const none_t&) { return empty(); }
/**
* @brief Returns the value.
*/
inline T& operator*() {
CPPA_REQUIRE(valid());
return m_value;
}
/**
* @brief Returns the value.
*/
inline const T& operator*() const {
CPPA_REQUIRE(valid());
return m_value;
}
/**
* @brief Returns the value.
*/
inline const T* operator->() const {
CPPA_REQUIRE(valid());
return &m_value;
}
/**
* @brief Returns the value.
*/
inline T* operator->() {
CPPA_REQUIRE(valid());
return &m_value;
}
/**
* @brief Returns the value.
*/
inline T& get() {
CPPA_REQUIRE(valid());
return m_value;
}
/**
* @brief Returns the value.
*/
inline const T& get() const {
CPPA_REQUIRE(valid());
return m_value;
}
/**
* @brief Returns the value. The value is set to @p default_value
* if <tt>valid() == false</tt>.
* @post <tt>valid() == true</tt>
*/
inline const T& get_or_else(const T& default_value) const {
if (valid()) return get();
return default_value;
}
private:
bool m_valid;
union { T m_value; };
void destroy() {
if (m_valid) {
m_value.~T();
m_valid = false;
}
}
template<typename V>
void cr(V&& value) {
CPPA_REQUIRE(!valid());
m_valid = true;
new (&m_value) T (std::forward<V>(value));
}
};
template<typename T>
class optional<T&> {
public:
typedef T type;
optional(const none_t& = none) : m_value(nullptr) { }
optional(T& value) : m_value(&value) { }
optional(const optional& other) = default;
optional& operator=(const optional& other) = default;
inline bool valid() const { return m_value != nullptr; }
inline bool empty() const { return !valid(); }
inline explicit operator bool() const { return valid(); }
inline bool operator!() const { return empty(); }
inline bool operator==(const none_t&) { return empty(); }
inline T& operator*() {
CPPA_REQUIRE(valid());
return *m_value;
}
inline const T& operator*() const {
CPPA_REQUIRE(valid());
return *m_value;
}
inline T* operator->() {
CPPA_REQUIRE(valid());
return m_value;
}
inline const T* operator->() const {
CPPA_REQUIRE(valid());
return m_value;
}
inline T& get() {
CPPA_REQUIRE(valid());
return *m_value;
}
inline const T& get() const {
CPPA_REQUIRE(valid());
return *m_value;
}
inline const T& get_or_else(const T& default_value) const {
if (valid()) return get();
return default_value;
}
private:
T* m_value;
};
template<>
class optional<void> {
public:
optional(const unit_t&) : m_valid(true) { }
optional(const none_t& = none) : m_valid(false) { }
inline bool valid() const { return m_valid; }
inline bool empty() const { return !m_valid; }
inline explicit operator bool() const { return valid(); }
inline bool operator!() const { return empty(); }
inline bool operator==(const none_t&) { return empty(); }
inline const unit_t& operator*() const { return unit; }
private:
bool m_valid;
};
/** @relates option */
template<typename T>
struct is_optional { static constexpr bool value = false; };
template<typename T>
struct is_optional<optional<T>> { static constexpr bool value = true; };
/** @relates option */
template<typename T, typename U>
bool operator==(const optional<T>& lhs, const optional<U>& rhs) {
if ((lhs) && (rhs)) return *lhs == *rhs;
return false;
}
/** @relates option */
template<typename T, typename U>
bool operator==(const optional<T>& lhs, const U& rhs) {
if (lhs) return *lhs == rhs;
return false;
}
/** @relates option */
template<typename T, typename U>
bool operator==(const T& lhs, const optional<U>& rhs) {
return rhs == lhs;
}
/** @relates option */
template<typename T, typename U>
bool operator!=(const optional<T>& lhs, const optional<U>& rhs) {
return !(lhs == rhs);
}
/** @relates option */
template<typename T, typename U>
bool operator!=(const optional<T>& lhs, const U& rhs) {
return !(lhs == rhs);
}
/** @relates option */
template<typename T, typename U>
bool operator!=(const T& lhs, const optional<U>& rhs) {
return !(lhs == rhs);
}
} // namespace cppa
#endif // CPPA_OPTION_HPP
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