RcCache. - A simple cache that wraps references that point to values to reference counted values in Rust. Mostly written by GPT-4

rc_cache.rs

use std::{cell::RefCell, collections::HashMap, hash::Hash, rc::Rc};

#[derive(Debug)]
pub struct RcCache<K, V>
where
    K: Eq + Hash + Clone,
    V: Clone,
{
    data: RefCell<HashMap<K, Rc<V>>>,
}

impl<K, V> Default for RcCache<K, V>
where
    K: Eq + Hash + Clone,
    V: Clone,
{
    fn default() -> Self {
        Self {
            data: Default::default(),
        }
    }
}

impl<K, V> RcCache<K, V>
where
    K: Eq + Hash + Clone,
    V: Clone,
{
    pub fn get<F>(&self, key: K, value_fn: F) -> Rc<V>
    where
        F: FnOnce(&K) -> V,
    {
        let mut data = self.data.borrow_mut();
        let entry = data.entry(key.clone());

        Rc::clone(entry.or_insert_with(|| Rc::new(value_fn(&key))))
    }
}