mirror of
https://github.com/matrix-construct/construct
synced 2024-11-26 16:52:44 +01:00
72 lines
1.9 KiB
C++
72 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_VA_RTTI_H
|
|
|
|
namespace ircd::util
|
|
{
|
|
struct va_rtti;
|
|
|
|
const size_t VA_RTTI_MAX_SIZE
|
|
{
|
|
12
|
|
};
|
|
}
|
|
|
|
//
|
|
// Similar to a va_list, but conveying std-c++ type data acquired from a variadic template
|
|
// parameter pack acting as the ...) elipsis. This is used to implement fmt::snprintf(),
|
|
// exceptions and logger et al in their respective translation units rather than the header
|
|
// files.
|
|
//
|
|
// Limitations: The choice of a fixed array of N is because std::initializer_list doesn't
|
|
// work here and other containers may be heavy in this context. Ideas to improve this are
|
|
// welcome.
|
|
//
|
|
struct ircd::util::va_rtti
|
|
:std::array<std::pair<const void *, const std::type_info *>, ircd::util::VA_RTTI_MAX_SIZE>
|
|
{
|
|
using base_type = std::array<value_type, ircd::util::VA_RTTI_MAX_SIZE>;
|
|
|
|
static constexpr size_t max_size()
|
|
{
|
|
return std::tuple_size<base_type>();
|
|
}
|
|
|
|
size_t argc;
|
|
const size_t &size() const
|
|
{
|
|
return argc;
|
|
}
|
|
|
|
template<class... Args>
|
|
va_rtti(Args&&... args)
|
|
:base_type
|
|
{{
|
|
std::make_pair(std::addressof(args), std::addressof(typeid(Args)))...
|
|
}}
|
|
,argc
|
|
{
|
|
sizeof...(args)
|
|
}
|
|
{
|
|
assert(argc <= max_size());
|
|
}
|
|
};
|
|
|
|
static_assert
|
|
(
|
|
sizeof(ircd::util::va_rtti) == (ircd::util::va_rtti::max_size() * 16) + 8,
|
|
"va_rtti should be (8 + 8) * N + 8;"
|
|
" where 8 + 8 are the two pointers carrying the argument and its type data;"
|
|
" where N is the max arguments;"
|
|
" where the final + 8 bytes holds the actual number of arguments passed;"
|
|
);
|