Lahzam

Lahzam is a modern C++20 header-only library for compile-time reflection of aggregate types. It enables fast and compact access to the members and their names of aggregates types, all without macros, annotations, or boilerplate.

Benchmarks

API contains very simple functions

1. lahzam::tie(aggregate) converts an aggregate to a std::tuple reference to apply algorithms on it.
2. lahzam::member_count<T> gives the member count of aggregates
3. lahzam::member_names<T> an object that iterates over all names of members.
4. lahzam::get<I>(aggregate) equalivent to std::get<I>(lahzam::tie(aggregate))
5. lahzam::get<"Name">(aggregate) gives the member of the specific name.
6. lahzam::apply(f,aggregate) similar to std::tuple apply.
7. lahzam::for_each_member(f,aggregate) similar to apply except the callable only takes a single arguement

Simple Examples

Access members by index

#include <lahzam/lahzam.hpp>
struct Point { int x, y; };

int main() {
    Point p{10,20};
    int x = lahzam::get<0>(p); // x == 10
    int y = lahzam::get<1>(p); // y == 20
}

Access members by names.

#include <lahzam/lahzam.hpp>
struct Point { int x, y; };

int main() {
    Point p{10,20};
    int x = lahzam::get<"x">(p); // x == 10
    int y = lahzam::get<"y">(p); // y == 20
}

Tie it into a tuple

#include <lahzam/lahzam.hpp>
struct Point { int x, y; };

int main() {
    Point p{10,20};
    std::tuple<int&,int&> tuple_ref = lahzam::tie(p); 
}

Benchmarks

MEMBERS is the amount of members in each type tested. TYPES is the amount of types in each test being tested.

Time is in seconds. Compiled using Clang.

MEMBERS	TYPES	boost::pfr::get	lahzam::get	glz::to_tie + get
128	32	8.38	4.76	8.26
64	64	6.25	3.87	5.54
32	128	5.67	3.44	4.66
16	256	5.99	3.74	3.96

glaze does not expose directly a get function it instead exposes to_tie which we can use.

lahzam is consistently ~2× faster than Boost and slightly faster than glaze.

MEMBERS	TYPES	boost::pfr::get_name	lahzam::member_names	glz::reflect::keys
128	32	13.28	4.21	20.39
64	64	12.08	4.28	16.15
32	128	11.78	4.60	14.56
16	256	12.38	5.59	14.34

Lahzam is up to ~3× faster member name access compared to Boost and ~4× faster than Glaze.