Arithmetic Nonmax

The arithmetic-nonmax crate provides NonMax* types for integer types that are guaranteed to never be their maximum value (MAX). Using NonMax* types enables memory layout optimization.

Additionally, arithmetic operations can be written intuitively as shown below. For example, in shortest path algorithms, using the Option<NonMax*> type allows you to leverage the type system while optimizing the memory layout. See Benchmarks for more details.

use arithmetic_nonmax::NonMaxU32;

let a: NonMaxU32 = NonMaxU32::new(5).unwrap();

let b = NonMaxU32::ZERO;
let c = a + b; // Arithmetic operations between NonMaxU32 types
assert_eq!(a, c);

let d = a * 5; // Arithmetic operations with primitive integers
assert!(a < d);
assert_eq!(d.to_string(), "25"); // Can be converted to string

Memory layout optimization can be verified as follows:

use arithmetic_nonmax::*;

// Check byte size for u32
assert_eq!(std::mem::size_of::<NonMaxU32>(), 4);
assert_eq!(std::mem::size_of::<Option<NonMaxU32>>(), 4);
assert_eq!(std::mem::size_of::<u32>(), 4);
assert_eq!(std::mem::size_of::<Option<u32>>(), 8);

// Check byte size for Option<NonMax*>
assert_eq!(std::mem::size_of::<Option<NonMaxU8>>(), 1);
assert_eq!(std::mem::size_of::<Option<NonMaxU16>>(), 2);
assert_eq!(std::mem::size_of::<Option<NonMaxU32>>(), 4);
assert_eq!(std::mem::size_of::<Option<NonMaxU64>>(), 8);
assert_eq!(std::mem::size_of::<Option<NonMaxU128>>(), 16);
assert_eq!(std::mem::size_of::<Option<NonMaxI8>>(), 1);
assert_eq!(std::mem::size_of::<Option<NonMaxI16>>(), 2);
assert_eq!(std::mem::size_of::<Option<NonMaxI32>>(), 4);
assert_eq!(std::mem::size_of::<Option<NonMaxI64>>(), 8);
assert_eq!(std::mem::size_of::<Option<NonMaxI128>>(), 16);

Benchmarks

Benchmarks are available in benches/comparison.rs. They compare execution time and memory usage between using and not using NonMax types.

Similar Libraries

• nonmax
• nonany

License

CC0 1.0 Universal