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construct/include/ircd/util/unique_iterator.h

78 lines
1.9 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
#pragma once
#define HAVE_IRCD_UTIL_UNIQUE_ITERATOR_H
namespace ircd {
inline namespace util
{
template<class container,
class iterator = typename container::iterator>
struct unique_iterator;
template<class container>
struct unique_const_iterator;
}}
//
// For objects using the pattern of adding their own instance to a container
// in their constructor, storing an iterator as a member, and then removing
// themselves using the iterator in their destructor. It is unsafe to do that.
// Use this instead; or better, use ircd::instance_list<>
//
template<class container,
class iterator>
struct ircd::util::unique_iterator
{
container *c;
iterator it;
unique_iterator(container &c, iterator it)
:c{&c}
,it{std::move(it)}
{}
unique_iterator()
:c{nullptr}
{}
unique_iterator(const unique_iterator &) = delete;
unique_iterator(unique_iterator &&o) noexcept
:c{std::move(o.c)}
,it{std::move(o.it)}
{
o.c = nullptr;
}
unique_iterator &operator=(const unique_iterator &) = delete;
unique_iterator &operator=(unique_iterator &&o) noexcept
{
this->~unique_iterator();
c = std::move(o.c);
it = std::move(o.it);
o.c = nullptr;
return *this;
}
~unique_iterator() noexcept
{
if(c)
c->erase(it);
}
};
template<class container>
struct ircd::util::unique_const_iterator
:unique_iterator<container, typename container::const_iterator>
{
using iterator_type = typename container::const_iterator;
using unique_iterator<container, iterator_type>::unique_iterator;
};