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#pragma once
// borrow.hpp - a non-null, unowned, pointer
//
// Copyright © 2014 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 "fwd.hpp"
#include <cstdlib>
#include <iterator>
#include "option.hpp"
// unit tests currention in option_test.cpp
namespace tmwa
{
// TODO see if const-by-default is a thing
template<class T>
class Borrowed
{
T *stupid;
public:
Borrowed() = delete;
explicit
Borrowed(T *p) : stupid(p)
{
if (!p) abort();
}
T& operator *() const
{
return *stupid;
}
T *operator ->() const
{
return stupid;
}
template<class U>
Borrowed<U> downcast_to() const
{
static_assert(std::is_base_of<T, U>::value, "base check");
static_assert(!std::is_same<T, U>::value, "same check");
return Borrowed<U>(static_cast<U *>(stupid));
}
template<class U>
Borrowed<U> upcast_to() const
{
static_assert(std::is_base_of<U, T>::value, "base check");
static_assert(!std::is_same<T, U>::value, "same check");
return Borrowed<U>(stupid);
}
friend bool operator == (Borrowed l, Borrowed r)
{
return l.stupid == r.stupid;
}
friend bool operator != (Borrowed l, Borrowed r)
{
return !(l == r);
}
};
namespace option
{
template<class T>
class OptionRepr<Borrowed<T>>
{
T *stupider;
public:
void set_none() { stupider = nullptr; }
void post_set_some() {}
bool is_some() const { return stupider != nullptr; }
Borrowed<T> *ptr() { return reinterpret_cast<Borrowed<T> *>(&stupider); }
const Borrowed<T> *ptr() const { return reinterpret_cast<const Borrowed<T> *>(&stupider); }
};
}
template<class T>
using P = Borrowed<T>;
template<class T>
Borrowed<T> borrow(T& ref)
{
return Borrowed<T>(&ref);
}
template<class T>
T *as_raw_pointer(Option<Borrowed<T>> ptr)
{
return &*TRY_UNWRAP(ptr, return nullptr);
}
} // namespace tmwa
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