checkito 5.0.0

A safe, efficient and simple QuickCheck-inspired library to generate shrinkable random data mainly oriented towards generative/property/exploratory testing.
Documentation 
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use crate::{generate::Generate, shrink::Shrink, state::State};

#[derive(Debug, Clone)]
pub struct FilterMap<G: ?Sized, F> {
    pub(crate) filter: F,
    pub(crate) generator: G,
}

#[derive(Debug, Clone)]
pub struct Shrinker<S, F> {
    shrinker: S,
    filter: F,
}

impl<G: Generate + ?Sized, T, F: Fn(G::Item) -> Option<T> + Clone> Generate for FilterMap<G, F> {
    type Item = Option<T>;
    type Shrink = Shrinker<G::Shrink, F>;

    const CARDINALITY: Option<u128> = G::CARDINALITY;

    fn generate(&self, state: &mut State) -> Self::Shrink {
        Shrinker {
            shrinker: self.generator.generate(state),
            filter: self.filter.clone(),
        }
    }

    fn cardinality(&self) -> Option<u128> {
        self.generator.cardinality()
    }
}

impl<S: Shrink, T, F: Fn(S::Item) -> Option<T> + Clone> Shrink for Shrinker<S, F> {
    type Item = Option<T>;

    fn item(&self) -> Self::Item {
        (self.filter)(self.shrinker.item())
    }

    fn shrink(&mut self) -> Option<Self> {
        Some(Self {
            shrinker: self.shrinker.shrink()?,
            filter: self.filter.clone(),
        })
    }
}