README.md

Hope

NOTE:

This repository should be considered a public archive. No updates will be released. The hope library is in the process of being reworked (divided into thematic libraries):

metaprogramming

logger

serialization/static-reflection

memory/allocator

concurrency

json

Library purpose

Here are the things that I use or would like to use in my daily development. When I find an interesting technology, I immediately add it here. As a result, this repository will contain all the most interesting, in my opinion, things from the c ++ language. You can find here my implementation of static reflection (based on magic-get idea) and wich used type loopholes. I also reworked some things from the Loki library, for example the small object allocator. Of course, here is the most important thing in c ++ in my opinion - the list of types. With a variety of examples.

System requirements

The bulk of the library runs in c ++ 14, some modules require c ++ 17. The library has no third-party dependencies, and uses stl to a minimum.

Build

• Just clone the repository (using git clone for instance)
• Main part of the library is header only, only small object allocator is needed to be build
• Run cmake --build at the root directory
• Enjoy

Examples

Small objects

To use the allocator for small objects, you just need to inherit from small_object; And thats all! See readme for more details.

// client_side_code.h
#include <hope/memory/small_object/small_object.h>
class realy_small_object : public hope::memory::small_object{
    // ...
}
// source.cpp
auto* object = new really_small_object;
// ...
delete object;

Tuples

To make tuple from struct you may use two variants of methods, c++14 based and unsafe (used C-style cast) or c++17 based on structured bindings. NOTE! Only POD objects is currently available, tuple does not guarantee proper work with complicated structs.

#include <hope/tuple/tuple_from_struct.h>

struct your_struct final {
    double i; float g; int k;
};
// ...
constexpr your_struct st{ 0.1, 0.1f, 11 };
constexpr auto test_tuple = hope::tuple_from_struct(st); // You may use constexpr; safe version
constexpr auto test_tuple_unsafe = hope::tuple_from_struct_unsafe(st); // potentially unsafe version
// You can print out tuples: 
std::cout << test_tuple << std::endl; // the result is:
// { 0.1, 0.1f, 11 };

Typelist

For instance, you want to find out the real type (index) of your polymorphic object using dynamic_cast (Yeah, this is not a good practice...) but:

struct base { virtual ~base(){}};
struct der1 : base{};
struct der2 : base{};
struct der3 : base{};

constexpr auto types = hope::typelist<der1, der2, der3>;
constexpr auto size = size(types);

std::size_t find_index(BaseType* link) noexcept {
    // ReSharper disable once CppEntityUsedOnlyInUnevaluatedContext
    return find_if(types, [&](auto&& holder) {
        using type = typename std::decay_t<decltype(holder)>::Type;
        constexpr std::size_t index = find<type>(types);
        return links[index] == nullptr &&  dynamic_cast<type*>(link) != nullptr;
    });
}
      
constexpr auto seq = std::make_index_sequence<size>();
auto* link = new der2;
const auto index = try_cast(link, seq);

See for more typelst examples

Serialization

If you want to serialize aggregate - like structure using change mask (for instance). You can use hope::serialization::pod_serializer. Basic principles: On first step serializer/deserealizer create tuple of references to the each field of specified structure, then iterate through fields and call special method to each of them. Serializer compares each field and fill bit mask. After all writes it before main data. Deserializer operates in reverse order. You have the ability to specify custom serializers as template arguments, this is useful for additional compression of custom structures.