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|
// 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));
}
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