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use crate::Fate;
use crate::adapters::{BoxedDieOnce, FlatMapDie, FlattenDie, MapDie};
/// Trait for generating a single pseudorandom value of type `T`.
pub trait DieOnce<T> {
/// Consumes the generator and generates a pseudorandom value.
///
/// The [`Fate`] is the only source of the randomness. Besides that, the generation is
/// deterministic.
fn roll_once(self, fate: Fate) -> T;
/// Creates a new [`DieOnce`] by mapping the generated values of `self`.
///
/// The function `f` will be applied to the generated value of `self`. The result of the
/// function is the generated value of the new [`DieOnce`].
fn map_once<U, F>(self, f: F) -> MapDie<T, U, Self, F>
where
Self: Sized,
F: FnOnce(T) -> U,
{
MapDie::new(self, f)
}
/// Creates a new [`DieOnce`] whose value is generated by the generated [`DieOnce`] of `self`.
fn flatten_once<U>(self) -> FlattenDie<U, T, Self>
where
Self: Sized,
T: DieOnce<U>,
{
FlattenDie::new(self)
}
/// Creates a new [`DieOnce`] similar to [`map_once`], except that the mapping
/// produces a [`DieOnce`].
///
/// The function `f` will be applied to the generated value of `self`. The result of the
/// function is a [`DieOnce`] that generate the value for the new [`DieOnce`].
///
/// It is semantically equivalent to `self.map_once(f).flatten_once()`.
///
/// [`map_once`]: DieOnce::map_once
fn flat_map_once<U, DU, F>(self, f: F) -> FlatMapDie<T, U, Self, DU, F>
where
Self: Sized,
DU: DieOnce<U>,
F: FnOnce(T) -> DU,
{
FlatMapDie::new(self, f)
}
/// Puts `self` behind a [`Box`] pointer.
fn boxed_once<'a>(self) -> BoxedDieOnce<'a, T>
where
Self: Sized + 'a,
{
BoxedDieOnce::new(self)
}
}