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//! Functions for mapping integers to the number of steps they take to reach 1.

use beetle_nonzero::NonZeroUnchecked;

use crate::Collatz;

/// Maps each number N in the range `nums` to its steps to reach 1 using steps::basic.
/// Performance should be pretty good, but consider using steps_range::omega for better performance.

pub fn alpha<T: Collatz>(
    start: NonZeroUnchecked<T>,
    stop: NonZeroUnchecked<T>,
) -> impl Iterator<Item = u32> {
    let [start, stop] = [start.value, stop.value];
    num::iter::range(start, stop).map(|x| crate::steps::alpha(NonZeroUnchecked::new(x)))
}

/// Ideally much faster than steps_range::alpha, by use of steps::omega instea of steps::alpha.
///
/// Potentially less stable as a result, and may panic or overflow more often, I'm not sure yet.
pub fn omega<T: Collatz>(
    start: NonZeroUnchecked<T>,
    stop: NonZeroUnchecked<T>,
) -> impl Iterator<Item = Option<u32>> {
    let (start, stop) = (start.value, stop.value);
    num::iter::range(start, stop).map(|x| crate::steps::omega(NonZeroUnchecked::new(x)))
}