83 lines
1.3 KiB
Rust
83 lines
1.3 KiB
Rust
// Test basic functionality of control flow in a const context.
|
|
|
|
//@ run-pass
|
|
|
|
const X: u32 = 4;
|
|
const Y: u32 = 5;
|
|
|
|
const ABS_DIFF: u32 = if X < Y {
|
|
Y - X
|
|
} else {
|
|
X - Y
|
|
};
|
|
|
|
const fn abs_diff(a: u32, b: u32) -> u32 {
|
|
match (a, b) {
|
|
(big, little) if big > little => big - little,
|
|
(little, big) => big - little,
|
|
}
|
|
}
|
|
|
|
const fn gcd(a: u32, b: u32) -> u32 {
|
|
if b == 0 {
|
|
return a;
|
|
}
|
|
|
|
gcd(b, a % b)
|
|
}
|
|
|
|
const fn fib(n: u64) -> u64 {
|
|
if n == 0 {
|
|
return 0;
|
|
}
|
|
|
|
let mut fib = (0, 1);
|
|
let mut i = 1;
|
|
while i < n {
|
|
fib = (fib.1, fib.0 + fib.1);
|
|
i += 1;
|
|
}
|
|
|
|
fib.1
|
|
}
|
|
|
|
const fn is_prime(n: u64) -> bool {
|
|
if n % 2 == 0 {
|
|
return false;
|
|
}
|
|
|
|
let mut div = 3;
|
|
loop {
|
|
if n % div == 0 {
|
|
return false;
|
|
}
|
|
|
|
if div * div > n {
|
|
return true;
|
|
}
|
|
|
|
div += 2;
|
|
}
|
|
}
|
|
|
|
macro_rules! const_assert {
|
|
($expr:expr) => {
|
|
const _: () = assert!($expr);
|
|
assert!($expr);
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
const_assert!(abs_diff(4, 5) == abs_diff(5, 4));
|
|
const_assert!(ABS_DIFF == abs_diff(5, 4));
|
|
|
|
const_assert!(gcd(48, 18) == 6);
|
|
const_assert!(gcd(18, 48) == 6);
|
|
|
|
const_assert!(fib(2) == 1);
|
|
const_assert!(fib(8) == 21);
|
|
|
|
const_assert!(is_prime(113));
|
|
const_assert!(!is_prime(117));
|
|
}
|