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//
// Copyright © 2017 Arm Ltd. All rights reserved.
// SPDX-License-Identifier: MIT
//
#pragma once
#include "Exceptions.hpp"
namespace armnn
{
// NOTE: the members of the Optional class don't follow the ArmNN
// coding convention because the interface to be close to
// the C++-17 interface so we can easily migrate to std::optional
// later.
template <typename T>
class Optional final
{
public:
Optional(T&& value)
: m_HasValue{true}
{
new (m_Storage) T(value);
}
Optional(const T& value)
: m_HasValue{true}
{
new (m_Storage) T(value);
}
Optional(const Optional& other)
: m_HasValue{false}
{
*this = other;
}
Optional() noexcept
: m_HasValue{false}
{
}
~Optional()
{
reset();
}
operator bool() const noexcept
{
return has_value();
}
Optional& operator=(T&& value)
{
reset();
new (m_Storage) T(value);
m_HasValue = true;
return *this;
}
Optional& operator=(const T& value)
{
reset();
new(m_Storage) T(value);
m_HasValue = true;
return *this;
}
Optional& operator=(const Optional& other)
{
reset();
if (other.has_value())
{
new (m_Storage) T(other.value());
m_HasValue = true;
}
return *this;
}
const T& value() const
{
if (!has_value())
{
throw BadOptionalAccessException("Optional has no value");
}
auto valuePtr = reinterpret_cast<const T*>(m_Storage);
return *valuePtr;
}
T& value()
{
if (!has_value())
{
throw BadOptionalAccessException("Optional has no value");
}
auto valuePtr = reinterpret_cast<T*>(m_Storage);
return *valuePtr;
}
bool has_value() const noexcept
{
return m_HasValue;
}
void reset()
{
if (has_value())
{
value().T::~T();
m_HasValue = false;
}
}
private:
alignas(alignof(T)) unsigned char m_Storage[sizeof(T)];
bool m_HasValue;
};
}
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