51 lines
1.3 KiB
Rust
51 lines
1.3 KiB
Rust
/// Result returned by [`Comparator::compare`].
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#[derive(Debug, PartialEq, Eq)]
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pub enum Comparison {
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L,
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/// Compared values were equal.
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E,
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R,
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}
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/// Returns [`Comparison`] saying which value is smaller.
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///
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/// ```rust
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/// # use radn::flow::comparator::*;
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/// assert_eq!(DefaultComparator.compare(&1, &3), Comparison::L);
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/// assert_eq!(DefaultComparator.compare(&2, &2), Comparison::E);
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/// assert_eq!(DefaultComparator.compare(&3, &1), Comparison::R);
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/// ```
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pub trait Comparator<A>: Send + Sync {
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fn compare(&self, kl: &A, kr: &A) -> Comparison;
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fn equal(&self, kl: &A, kr: &A) -> bool {
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matches!(self.compare(kl, kr), Comparison::E)
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}
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}
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/// Implementation of a [Comparator] relying on [`Ord`].
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pub struct DefaultComparator;
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impl<A: Ord> Comparator<A> for DefaultComparator {
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fn compare(&self, kl: &A, kr: &A) -> Comparison {
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match kl.cmp(kr) {
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std::cmp::Ordering::Less => Comparison::L,
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std::cmp::Ordering::Equal => Comparison::E,
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std::cmp::Ordering::Greater => Comparison::R,
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}
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}
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}
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pub struct RcComparator<C>(C);
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mod rc_comparator_impl {
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use super::*;
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use std::sync::Arc;
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impl<A, C: Comparator<A>> Comparator<Arc<A>> for RcComparator<C> {
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fn compare(&self, kl: &Arc<A>, kr: &Arc<A>) -> Comparison {
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self.0.compare(kl, kr)
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}
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}
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}
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