46 lines
1.5 KiB
Rust
46 lines
1.5 KiB
Rust
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use std::time::Duration;
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/// A helper trait for primitive types that do not yet implement saturating arithmetic methods
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pub trait SaturatingArithmetic<T> {
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fn sol_saturating_add(&self, rhs: Self) -> Self;
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fn sol_saturating_sub(&self, rhs: Self) -> Self;
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fn sol_saturating_mul(&self, rhs: T) -> Self;
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}
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/// Saturating arithmetic for Duration, until Rust support moves from nightly to stable
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/// Duration::MAX is constructed manually, as Duration consts are not yet stable either.
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impl SaturatingArithmetic<u32> for Duration {
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fn sol_saturating_add(&self, rhs: Self) -> Self {
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self.checked_add(rhs)
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.unwrap_or_else(|| Self::new(u64::MAX, 1_000_000_000u32.saturating_sub(1)))
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}
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fn sol_saturating_sub(&self, rhs: Self) -> Self {
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self.checked_sub(rhs).unwrap_or_else(|| Self::new(0, 0))
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}
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fn sol_saturating_mul(&self, rhs: u32) -> Self {
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self.checked_mul(rhs)
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.unwrap_or_else(|| Self::new(u64::MAX, 1_000_000_000u32.saturating_sub(1)))
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}
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}
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#[cfg(test)]
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pub mod tests {
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use super::*;
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#[test]
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fn test_duration() {
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let empty_duration = Duration::new(0, 0);
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let max_duration = Duration::new(u64::MAX, 1_000_000_000 - 1);
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let duration = Duration::new(u64::MAX, 0);
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let add = duration.sol_saturating_add(duration);
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assert_eq!(add, max_duration);
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let sub = duration.sol_saturating_sub(max_duration);
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assert_eq!(sub, empty_duration);
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let mult = duration.sol_saturating_mul(u32::MAX);
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assert_eq!(mult, max_duration);
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}
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}
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