12 releases (6 breaking)
0.9.0 | Oct 12, 2024 |
---|---|
0.8.0 | Feb 7, 2024 |
0.7.1 | Feb 1, 2023 |
0.7.0 | Sep 30, 2022 |
0.3.1 | Jul 26, 2021 |
#310 in Rust patterns
95KB
1.5K
SLoC
Ranged integers [nightly only]
Note: the library relies on the incomplete Rust features:
- It causes ICEson some Rust toolchains,
- The usage may increase the time compilation time heavily.
- The current version (0.9.0) was tested on nightly-2024-10-12.
Provides a generic type Ranged<MIN, MAX>
representing an integer
within a specified range. It automatically chooses the data size guided by
the range specified (so Ranged<-50, 50>
is of 1 byte while
Ranged<-20_000, 100_000>
is of 4 bytes) and supports the arithmetic operations
with automatic bound recalculation and range iteration. The fixed sized arrays can be
indexed with a ranged integer having the fitting bounds.
The conversion and arithmetic functions catch the errors such as possible overflow and zero division at compile time.
Example
#![allow(incomplete_features)]
#![feature(adt_const_params, generic_const_exprs)]
extern crate ranged_integers;
use ranged_integers::*;
// Consider a simple race game. The player rolls a
// die and then moves forward, backward or forward
// with the double speed according to some rules.
enum MoveType {MoveForward, DoubleSpeed, MoveBackward}
// Get a die roll using a standard random number generator
fn roll_die(rng: &mut dyn rand::RngCore) -> Ranged<1, 6> {
let random: u8 = rng.gen();
// The consistency is proved at compile time:
// r!(6) means Ranged<6,6> with the value 6
// r!(1) means Ranged<1,1> with the value 1
// u8 % Ranged<6, 6> = Ranged<0, 5>
// Ranged<0, 5> + Ranged<1, 1> = Ranged<1, 6>
random % r!(6) + r!(1)
}
// Calculate where the player must move
// The result fits the range -6..=12
fn move_player(
mtype: MoveType,
dice_points: Ranged<1, 6>
) -> Ranged<-6, 12>
{
match move_type {
MoveType::MoveForward => {
// Expand 1..=6 to -6..=12
dice_points.expand()
}
MoveType::DoubleSpeed => {
let mv = dice_points*r!(2); // Ranged<2, 12>
mv.expand() // Expand to -6..=12
}
MoveType::MoveBackward => {
let mv = -dice_points; // Ranged<-6, -1>
mv.expand() // Expand to -6..=12
}
}
}