[−][src]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(n <= 100)] fn fib(n: i64) -> i64 { if n == 0 || n == 1 { return n; } fib(n - 1) + fib(n - 2) }
You need to specify upper-bound of arguments statically.
Bounds can be specified by <
or <=
and must be integer literal.
Calling memoised function by arguments that out of bounds
cause panic.
You can specify multiple keys for memoise.
use memoise::memoise; #[memoise(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
You can also specify lower-bounds of keys.
use memoise::memoise; #[memoise(-100 <= n <= 100)] fn foo(n: i64) -> i64 { todo!() }
If lower-bounds are not specified, concider '0 <= _' is specified implicitly.
And you can specify keys as expressions instead of just variable names.
use memoise::memoise; #[memoise(n * 100 + m <= 100)] fn bar(n: i64, m: i64) -> i64 { todo!() }
Without bounds, cache table will be allocated dynamically.
use memoise::memoise; #[memoise(n, k)] fn comb(n: usize, k: usize) -> usize { if k == 0 { return 1; } if n == 0 { return 0; } comb(n - 1, k - 1) + comb(n - 1, k) }
memoise_map
memoises a function with BTreeMap
.
use memoise::memoise_map; #[memoise_map(n, k)] fn comb(n: usize, k: usize) -> usize { if k == 0 { return 1; } if n == 0 { return 0; } comb(n - 1, k - 1) + comb(n - 1, k) }
Attribute Macros
memoise | Memoise function by using |
memoise_map | Memoise function by using |