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construct/include/ircd/buffer/fixed_buffer.h
2018-03-12 22:48:56 -07:00

78 lines
2.4 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_BUFFER_FIXED_BUFFER_H
/// fixed_buffer wraps an std::array with construction and conversions apropos
/// the ircd::buffer suite. fixed_buffer should be punnable. Its only memory
/// footprint is the array itself and
///
template<class buffer,
size_t SIZE>
struct ircd::buffer::fixed_buffer
:std::array<typename std::remove_const<typename buffer::value_type>::type, SIZE>
{
using mutable_type = typename std::remove_const<typename buffer::value_type>::type;
using const_type = typename std::add_const<mutable_type>::type;
using array_type = std::array<mutable_type, SIZE>;
operator buffer() const;
operator buffer();
using array_type::array_type;
fixed_buffer(const nullptr_t &);
fixed_buffer(const std::function<void (const mutable_buffer &)> &closure);
fixed_buffer(buffer b);
fixed_buffer() = default;
};
static_assert
(
// Assertion over an arbitrary but common template configuration.
std::is_standard_layout<ircd::buffer::fixed_buffer<ircd::buffer::const_buffer, 32>>::value,
"ircd::buffer::fixed_buffer must be standard layout"
);
template<class buffer,
size_t SIZE>
ircd::buffer::fixed_buffer<buffer, SIZE>::fixed_buffer(const nullptr_t &)
:array_type{{0}}
{}
template<class buffer,
size_t SIZE>
ircd::buffer::fixed_buffer<buffer, SIZE>::fixed_buffer(const std::function<void (const mutable_buffer &)> &closure)
{
closure(mutable_buffer{reinterpret_cast<mutable_buffer::iterator>(this->data()), this->size()});
}
template<class buffer,
size_t SIZE>
ircd::buffer::fixed_buffer<buffer, SIZE>::fixed_buffer(buffer b)
:array_type{std::begin(b), std::end(b)}
{}
template<class buffer,
size_t SIZE>
ircd::buffer::fixed_buffer<buffer, SIZE>::operator
buffer()
{
return { std::begin(*this), std::end(*this) };
}
template<class buffer,
size_t SIZE>
ircd::buffer::fixed_buffer<buffer, SIZE>::operator
buffer()
const
{
return { std::begin(*this), std::end(*this) };
}