Crate range_cmp 

This crate provides the RangeOrd trait on all types that implement Ord. This trait exposes a rcmp associated method that allows comparing a value with a range of values:

use range_cmp::{RangeOrd, RangeOrdering};
assert_eq!(15.rcmp(20..30), RangeOrdering::Below);
assert_eq!(25.rcmp(20..30), RangeOrdering::Inside);
assert_eq!(35.rcmp(20..30), RangeOrdering::Above);

Empty ranges

Unlike previous versions, the crate now handles empty ranges explicitly, instead of returning an arbitrary, representation-dependent answer. An empty range (such as 30..20 or 0..0) is reported as RangeOrdering::Empty:

use range_cmp::{RangeOrd, RangeOrdering};
assert_eq!(25.rcmp(30..20), RangeOrdering::Empty);
assert_eq!(0.rcmp(0..0), RangeOrdering::Empty);

Emptiness is judged from the bounds, not from the population of the type: ..0u32 is treated as a regular (non-empty) range even though no u32 is below 0.

Partial orders

The crate also provides the PartialRangeOrd trait on all types that implement PartialOrd. Because a partial order is not a line but a poset, a value cannot always be collapsed into a single Below/Inside/Above verdict: it may be incomparable with one or both bounds. partial_rcmp therefore returns a RangePosition, the pair of the value’s relationships to the lower and upper bounds, which never loses information:

use range_cmp::{PartialRangeOrd, RangeOrdering};
// `f64` is `PartialOrd` but not `Ord`.
assert_eq!(1.5_f64.partial_rcmp(2.0..3.0).ordering(), Some(RangeOrdering::Below));
assert_eq!(2.5_f64.partial_rcmp(2.0..3.0).ordering(), Some(RangeOrdering::Inside));
assert_eq!(3.5_f64.partial_rcmp(2.0..3.0).ordering(), Some(RangeOrdering::Above));
// `NaN` is incomparable with the bounds, so there is no single verdict:
assert_eq!(core::f64::NAN.partial_rcmp(2.0..3.0).ordering(), None);

no_std

The crate is #![no_std]: it has no dependencies and only relies on core, so it can be used in embedded and other environments without the standard library.

Structs

RangePosition

Full position of a value relative to a range, expressed as the pair of its relationships to the lower and the upper bound.

Enums

BoundOrdering

Position of a value relative to a single bound of a range.

RangeOrdering

Simplified result for RangeOrd::rcmp, obtained for totally ordered types or by collapsing a RangePosition through RangePosition::ordering.

Traits

BorrowRange

Helper trait to allow passing a range as either a owned value or a reference.

PartialRangeOrd

Trait to provide the partial_rcmp method, which allows comparing the type to a range. A blanket implementation is provided for all types that implement the PartialOrd trait.

RangeOrd

Trait to provide the rcmp method, which allows comparing the type to a range. A blanket implementation is provided for all types that implement the Ord trait.