mruby-c-ext-helpers

This mgem includes helpers for c/c++ extenstion i use frenquently, but are lacking from the core mruby distribution, namely number encoding and decoding, helping with deciding which type of Numeric to pick (Integer, Float, Bigint) etc.
Take a look at the test/cpp_tests.cpp file on how to use some of them, or the test.rb file there.

You need a c++17 compatible compiler to build this.

Sample code to wrap calling new and delete on a c++ class

#include <mruby/cpp_helpers.hpp>
MRB_CPP_DEFINE_TYPE(ClassName, UniqueIdentifier)
//add the above outside a function call

mrb_cpp_new<ClassName>(mrb, self, ...);

Put that in the initialize method of a mruby class which has the MRB_TT_DATA type and mruby will manage the lifetime of your c++ Object. Arguments will get forwarded to the new method of your c++ class.

Convert most c++ values to mruby objects:

#include <mruby/cpp_to_mrb_value.hpp>
std::vector<int> v = {1, 2, 3};
mrb_value arr = cpp_to_mrb_value(mrb, v);
assert(mrb_type(arr) == MRB_TT_ARRAY);
assert(RARRAY_LEN(arr) == 3);
assert(mrb_integer(mrb_ary_ref(mrb, arr, 0)) == 1);

This works with numbers, maps, sets, strings, vectors and a few more which can be represented in mruby.

convert most c numeric types to an mruby number:

#include <mruby/num_helpers.h>

size_t n = 15;
mrb_value number = mrb_convert_size_t(mrb, n);

long long l = -15;
number = mrb_convert_long_long(mrb, l);

convert most mruby objects to c++ values

#include <mruby/mrb_value_to_cpp.hpp>

mrb_value s = mrb_str_new_lit(mrb, "hello");
std::any as = mrb_value_to_any(mrb, s);
assert(std::any_cast<std::string>(as) == "hello");

this exposes the following functions:

MRB_API std::any mrb_value_to_any(mrb_state* mrb, mrb_value val);
MRB_API std::vector<std::any> mrb_array_to_vector(mrb_state* mrb, mrb_value ary);

// Map keys can be int64_t, double, or string
using MapKey = std::variant<mrb_int, mrb_float, std::string>;
MRB_API std::map<MapKey, std::any> mrb_hash_to_map(mrb_state* mrb, mrb_value hash);