Crate memoise

An attribute macro to memoise a function.

Usage

You can just add attribute memoise to normal functions that you want to memoise against arguments. For example:

use memoise::memoise;

#[memoise(keys(n = 100))]
fn fib(n: usize) -> usize {
    if n == 0 || n == 1 {
        return n;
    }
    fib(n - 1) + fib(n - 2)
}

You need to specify upper-bound of arguments statically. Calling memoised function by arguments on out of bounds cause panic.

You can specify multiple keys for memoise.

use memoise::memoise;

#[memoise(keys(n = 100, m = 50))]
fn comb(n: usize, m: usize) -> usize {
    if m == 0 {
        return 1;
    }
    if n == 0 {
        return 0;
    }
    comb(n - 1, m - 1) + comb(n - 1, m)
}

To reuse memoised functions depend on non-key arguments, you can reset memoise tables by calling automatic defined function named <function-name>_reset. On above code, the function comb_reset is defined, so you can call that function to reset the table.

let a = comb(10, 5); // calculation
comb_reset();        // reset the memoization table
let a = comb(10, 5); // calculation executed again

Attribute Macros

memoise