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https://github.com/marzer/type_list
A compiler-friendly variadic type list for C++.
https://github.com/marzer/type_list
Last synced: 6 days ago
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A compiler-friendly variadic type list for C++.
- Host: GitHub
- URL: https://github.com/marzer/type_list
- Owner: marzer
- License: mit
- Created: 2021-05-31T23:00:05.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2023-06-14T16:45:19.000Z (over 1 year ago)
- Last Synced: 2024-10-31T13:46:07.615Z (13 days ago)
- Language: C++
- Size: 86.9 KB
- Stars: 36
- Watchers: 5
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
- License: LICENSE
Awesome Lists containing this project
README
# `mz::type_list` [](./LICENSE) [][cpp_compilers] [][sponsor] [][gitter]
A variadic 'type list' for performing operations on lists of types in metaprogramming contexts. Optimized to be much more compiler-friendly than `std::tuple`.
See [Compilation speed humps: std::tuple](https://marzer.github.io/md_blog_2021_05_31_compilation_speed_humps_std_tuple.html) for a write-up on the sorts of optimizations applied herein.
Requires C++17.
## Synopsis
```cpp
namespace mz
{
template
struct type_list
{
// get the number of types in the list:
static constexpr size_t length = sizeof...(T);
// index of the first appearance of the specified type:
template
static constexpr size_t index_of = /* ... */;
// determine if a specified type appears in the list:
template
static constexpr bool contains = /* ... */;
// get a specific type:
template
using select = /* T...[Index] */;
// convenience alias for select<0>:
using first = select<0>;
// convenience alias for select<0> when length == 1:
using type = select<0>;
// get a 'slice' (sublist):
template
using slice = type_list* ... */>;
// adding on to the beginning of the list:
template
using prepend = type_list;
// adding on to the end of the list:
template
using append = type_list;
// recursively flatten child sublists:
using flatten = type_list* ... */>;
// remove all occurrences of the specified type:
template
using remove = type_list* ... */>;
};
// alias for a single-element list:
template
using type_tag = type_list;
}
```
## Usage
The library is a single header so the easiest way to use it is to drop [type_list.hpp] somewhere in your project.
Alternatively you can add `include` to your include paths then `#include `
There is also support for use as a `meson.build` subproject.
## Benchmarks
Single-threaded compilation of the example application on my Ryzen 3950X:
| | Clang 12 | GCC 10 | MSVC 19.29 |
| -------------- | ------------ | ----------- | ----------- |
| std::tuple | 6.448s | 3.185s | 7.965s |
| mz::type_list | 0.303s | 0.407s | 0.830s |
| speedup factor | 21.2x faster | 7.8x faster | 9.6x faster |
## License
MIT. See [LICENSE](LICENSE).
## Contributing
There are three ways you can contribute:
1. Reporting bug or making feature requests [here](https://github.com/marzer/type_list/issues/new)
2. Opening a pull request (⚠️ _caveat - see below_)
3. Becoming a [sponsor] ❤️
### Pull requests
`type_list.hpp` is programmatically extracted from a much larger project so I won't accept pull requests made for this repository directly; if you wish to contribute a bugfix or a feature, please find the type_list implementation [in this project](https://github.com/marzer/muu) and propose your changes there instead. I will then propagate them to this satellite library when they are merged.
[type_list.hpp]: include/mz/type_list.hpp
[license]: ./LICENSE
[cpp_compilers]: https://en.cppreference.com/w/cpp/compiler_support
[gitter]: https://gitter.im/marzer/community
[sponsor]: https://github.com/sponsors/marzer