Utility¶

The utility header file provides a set of general purpose utilities to simplify common programming tasks. Some of the functions are written to operate during compile-time, while others are written to operate during run-time.

namespace utils

Functions

template<typename T> T &get_reference(T &t)¶

Returns a reference to the value or dereferenced pointer.

This function template takes a forwarding reference to a value or pointer. If the argument is a pointer, it returns a reference to the value pointed to by the pointer. Otherwise, it returns the value itself.

Template Parameters:: T – The type of the argument, deduced automatically.
Parameters:: t – The value or pointer to be processed.
Throws:: std::bad_function_call – if the pointer is null.
Returns:: A reference to the value or dereferenced pointer.

template<typename T> T &get_reference(T *t)¶

template<auto Start, auto End, auto I, typename F> void constexpr_for(F &&f)¶

Executes a function in a compile-time loop.

This function template executes a given function in a compile-time loop from Start to End with a step of Inc. The function is called with the current index wrapped in an integral constant.

Template Parameters:

Start – The starting index of the loop.
End – The ending index of the loop.
I – The increment step for each iteration.
F – The type of the function to be called.

Parameters:

f – The function to be called with the current index.

Usage¶

The following examples demonstrates how to use the utility header file:

get_reference

Output:

1, 1, 1

constexpr_for

// this is rather naive example but it demonstrates how to use the constexpr_for
template <std::size_t N>
struct fibonacci : std::integral_constant<std::size_t,
    fibonacci<N-1>::value + fibonacci<N-2>::value> { };

template <>
struct fibonacci<0> : std::integral_constant<std::size_t, 0> {};

template <>
struct fibonacci<1> : std::integral_constant<std::size_t, 1> {};

template <>
struct fibonacci<2> : std::integral_constant<std::size_t, 1> {};

int main() {
    constexpr std::size_t n{10};
    std::array<std::size_t, n> fib{};
    utils::constexpr_for<0, n, 1>([&fib](auto i) {
        fib[i] = fibonacci<i>::value;
    });

    std::cout << fib[99] << std::endl;
}

Output:

3405478146