`bit::matrix` — Conditional Set/Flip

We have methods to set or flip the element values in a bit-matrix based on the return value from a function call.

constexpr bit::matrix&
1set_if(std::invocable<std::size_t, std::size_t> auto f);

constexpr bit::matrix&
2flip_if(std::invocable<std::size_t, std::size_t> auto f);

1: Sets element at (i, j) to 1 if f(i,j) != 0, otherwise sets it to 0.
2: Flips the value of element (i, j) if f(i,j) != 0, otherwise leaves it unchanged.

f is a function we expect to call as f(i,j) for each index pair.

Both methods return a reference to *this so they can be chained with other calls.

Example

#include <bit/bit.h>
int main()
{
    bit::matrix<> m(4,8);
    std::cout << "m:\n" << m << '\n';
    m.set_if([](std::size_t i, std::size_t j) { return (i + j) % 2; });
    std::cout << "m:\n" << m << '\n';
    m.flip_if([](std::size_t i, std::size_t j) { return (i + j) % 2; });
    std::cout << "m:\n" << m << '\n';
}

Output

m:
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│
m:
│0 1 0 1 0 1 0 1│
│1 0 1 0 1 0 1 0│
│0 1 0 1 0 1 0 1│
│1 0 1 0 1 0 1 0│
m:
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│
│0 0 0 0 0 0 0 0│

See Also