comparison: src/nanleast.rs
src/nanleast.rs
- changeset 199
- 32f5062ee477
- parent 198
- 3868555d135c
- child 200
- fbd4791f16bc
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| 198:3868555d135c | 199:32f5062ee477 |
|---|---|
| 1 /*! | |
| 2 This module provides an artificial total order of floating point numbers. | |
| 3 | |
| 4 The [`NaNLeast`]`<F>` container for `F` a [`Float`] puts `F` in an [`Ord`] total order with | |
| 5 `NaN` the least element. This allows the numbers to be sorted with `NaN` the “least important” | |
| 6 element when looking for the maximum. Thus erroneous computations producing `NaN` can be ignored | |
| 7 when there are good results. | |
| 8 */ | |
| 9 | |
| 10 use crate::types::Float; | |
| 11 use std::cmp::{PartialOrd,Ord,Ordering,Ordering::*}; | |
| 12 | |
| 13 /// A container for floating point numbers. | |
| 14 /// | |
| 15 /// The implementation of [`Ord`] for this type type sorts `NaN` as the least element. | |
| 16 #[derive(Debug, Clone, Copy)] | |
| 17 pub struct NaNLeast<F : Float>(pub F); | |
| 18 | |
| 19 impl<F : Float> Ord for NaNLeast<F> { | |
| 20 #[inline] | |
| 21 fn cmp(&self, NaNLeast(b) : &Self) -> Ordering { | |
| 22 let NaNLeast(a) = self; | |
| 23 match a.partial_cmp(b) { | |
| 24 None => match (a.is_nan(), b.is_nan()) { | |
| 25 (true, false) => Less, | |
| 26 (false, true) => Greater, | |
| 27 _ => Equal // The case (true, true) should not occur! | |
| 28 } | |
| 29 Some(order) => order | |
| 30 } | |
| 31 } | |
| 32 } | |
| 33 | |
| 34 impl<F : Float> PartialEq for NaNLeast<F> { | |
| 35 #[inline] | |
| 36 fn eq(&self, other : &Self) -> bool { self.cmp(other)==Equal } | |
| 37 } | |
| 38 | |
| 39 impl<F : Float> Eq for NaNLeast<F> { } | |
| 40 | |
| 41 impl<F : Float> PartialOrd for NaNLeast<F> { | |
| 42 #[inline] | |
| 43 fn partial_cmp(&self, other : &Self) -> Option<Ordering> { Some(self.cmp(other)) } | |
| 44 } |
