Struct Memoizer

pub struct Memoizer<U, V, F>
where
    U: Eq + Hash + Clone,
    V: Clone,
    F: Fn(U) -> V,
{ /* private fields */ }

The eponymous struct. Can only memoize function that takes a single argument and returns a single value, if you need more than this, you can use vectors, arrays or structs of your own to pass in more than one value.

Implementations

impl<U, V, F> Memoizer<U, V, F>

where U: Eq + Hash + Clone, V: Clone, F: Fn(U) -> V,

pub fn new(function: F) -> Memoizer<U, V, F>

Creates a new Memoize given a function.

Examples

let mut add_two = Memoizer::new(|n| {
   	n + 2
   });
assert_eq!(4, add_two.value(2));

pub fn value(&mut self, arg: U) -> V

Returns the value for the memoized function. If the function has already been called before, it will use the previous value. This means Memoizer should only be used for injective functions.

Examples

#[derive(Debug, Clone, Hash)]
    struct Dummy {
        pub id: usize,
        pub word: String,
    }

    /* PartialEq & Eq required for HashMap */
    impl PartialEq for Dummy {
        fn eq(&self, other: &Dummy) -> bool {
            self.id == other.id && self.word == other.word
        }
    }

   impl Eq for Dummy {}

let d = Dummy {
    id: 1,
    word: String::from("girls"),
};
let mut calc = Memoizer::new(|d: &Dummy| d.id + d.word.len());

 assert_eq!(6, calc.value(&d));
 assert_eq!(6, calc.value(&d));

Trait Implementations

impl<U, V, F> Debug for Memoizer<U, V, F>

where U: Eq + Hash + Clone + Debug, V: Clone + Debug, F: Fn(U) -> V + Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.