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Improve comments in iter::Step

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CAD97 2020-05-13 14:49:45 -04:00
parent f34322d71f
commit cef616b1dc
1 changed files with 3 additions and 3 deletions
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6
src/libcore/iter/range.rs
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@ -15,7 +15,7 @@ use super::{FusedIterator, TrustedLen};
/// This trait is `unsafe` because its implementation must be correct for
/// the safety of `unsafe trait TrustedLen` implementations, and the results
/// of using this trait can otherwise be trusted by `unsafe` code to be correct
/// and fulful the listed obligations.
/// and fulfill the listed obligations.
#[unstable(feature = "step_trait", reason = "recently redesigned", issue = "42168")]
pub unsafe trait Step: Clone + PartialOrd + Sized {
/// Returns the number of *successor* steps required to get from `start` to `end`.
@ -27,8 +27,8 @@ pub unsafe trait Step: Clone + PartialOrd + Sized {
///
/// For any `a`, `b`, and `n`:
///
/// * `steps_between(&a, &b) == Some(n)` if and only if `Step::forward(&a, n) == Some(b)`
/// * `steps_between(&a, &b) == Some(n)` if and only if `Step::backward(&a, n) == Some(a)`
/// * `steps_between(&a, &b) == Some(n)` if and only if `Step::forward_checked(&a, n) == Some(b)`
/// * `steps_between(&a, &b) == Some(n)` if and only if `Step::backward_checked(&a, n) == Some(a)`
/// * `steps_between(&a, &b) == Some(n)` only if `a <= b`
/// * Corollary: `steps_between(&a, &b) == Some(0)` if and only if `a == b`
/// * Note that `a <= b` does _not_ imply `steps_between(&a, &b) != None`;