range-utils

Motivation

The standard library has 6 (or even more?) different types of ranges, e.g. 0..=256, ..=256, 0.., .. represent all the same range in u8 (ranges like 0..3 and ..3 are some more ranges not listed before). The only "utililty" provided by the standard library is RangeBounds, which is quite useless if a more advances/generic use is required. For instance, .start_bound() does not return the actual start_bound if the start is unbounded, making it harder to implement functions for different range types.

Usage

This crate includes the trait RangeUtil<T> with the following methods:

• starts_at(&self) -> T: inclusive start bound, e.g. (0..3).starts_at() == 0, (..3_u8).starts_at() == 0
• ends_at(&self) -> T: inclusive end bound, e.g. (0..3).ends_at() == 2, (0..=2).ends_at() == 2, (..=2).ends_at() == 2, ...

The following methods have a default implementation (that does probably not need to be changed):

• includes(&self, &T) -> bool: .contains(&T) from RangeBounds<T> from the standard library, but implemented with starts_at() and ends_at()
• intersects(&self, other: &impl RangeUtil<T>) -> bool: whether two ranges intersect, e.g. 0..=2 and 2..3 do, while 0..2 and 2..3 don't
• intersection(&self, other: &impl RangeUtil<T>) -> Option<RangeInclusive<T>>: the intersection of two ranges with an inclusive range returned, e.g. (0..=3).intersects(&(1..)) == Some(1..=3)
• setminus(&self, other: &impl RangeUtil<T>) -> (Option<RangeInclusive<T>>, Option<RangeInclusive<T>>): the set self without the elements in other, e.g. (..100u8).setminus(&(50..)) == (Some(0..=50), None), or (..100u8).setminus(&(25..75)) == (Some(0..=24), Some(75..=99))