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core: Align cmp::le() with the other implementations

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Also add comments reminding that IEEE 754 requires unusual semantics for
comparison operators as applied to NaNs (x != x, if x = NaN), in case someone
in the future wants to get clever.
This commit is contained in:
Peter Williams 2013-01-12 18:48:19 -05:00 committed by Tim Chevalier
parent 7eae397e58
commit d5dc66ad31
1 changed files with 10 additions and 4 deletions
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14
src/libcore/cmp.rs
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@ -30,7 +30,10 @@ and `Eq` to overload the `==` and `!=` operators.
*
* Eventually this may be simplified to only require
* an `eq` method, with the other generated from
* a default implementation.
* a default implementation. However it should
* remain possible to implement `ne` separately, for
* compatibility with floating-point NaN semantics
* (cf. IEEE 754-2008 section 5.11).
*/
#[lang="eq"]
pub trait Eq {
@ -43,7 +46,10 @@ pub trait Eq {
*
* Eventually this may be simplified to only require
* an `le` method, with the others generated from
* default implementations.
* default implementations. However it should remain
* possible to implement the others separately, for
* compatibility with floating-point NaN semantics
* (cf. IEEE 754-2008 section 5.11).
*/
#[lang="ord"]
pub trait Ord {
@ -59,8 +65,8 @@ pub pure fn lt<T: Ord>(v1: &T, v2: &T) -> bool {
}
#[inline(always)]
pub pure fn le<T: Ord Eq>(v1: &T, v2: &T) -> bool {
(*v1).lt(v2) || (*v1).eq(v2)
pub pure fn le<T: Ord>(v1: &T, v2: &T) -> bool {
(*v1).le(v2)
}
#[inline(always)]