`bit::vector` — Conditional Change

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

1constexpr bit::vector &set_if(std::invocable<std::size_t, std::size_t> auto f);
2constexpr bit::vector &flip_if(std::invocable<std::size_t, std::size_t> auto f);

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

f is a function, and we expect to call f(i) for each set index.

These return a reference to *this, so can be chained with other calls.

Example

#include <bit/bit.h>
int main()
{
1    bit::vector<> v(16);
    std::cout << "v: " << v << '\n';
2    v.set_if([](std::size_t i) { return (i + 1) % 2; });
    std::cout << "v: " << v << '\n';
3    v.flip_if([](std::size_t i) { return (i + 1) % 2; });
    std::cout << "v: " << v << '\n';
}

1: Start with a bit-vector whose elements are all 0 by default.
2: Using the set_if method with a lambda to set the even indices 0,2,4,…
3: Using the flip_if method with a lambda to flip the even indices 0,2,4,…

Output

v: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
v: [1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0]
v: [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]

See Also