diff options
Diffstat (limited to 'src/exactly_one_err.rs')
-rw-r--r-- | src/exactly_one_err.rs | 82 |
1 files changed, 67 insertions, 15 deletions
diff --git a/src/exactly_one_err.rs b/src/exactly_one_err.rs index e4925ff..63485c9 100644 --- a/src/exactly_one_err.rs +++ b/src/exactly_one_err.rs @@ -1,5 +1,11 @@ +#[cfg(feature = "use_std")] +use std::error::Error; +use std::fmt::{Debug, Display, Formatter, Result as FmtResult}; + use std::iter::ExactSizeIterator; +use either::Either; + use crate::size_hint; /// Iterator returned for the error case of `IterTools::exactly_one()` @@ -10,12 +16,12 @@ use crate::size_hint; /// /// This is very similar to PutBackN except this iterator only supports 0-2 elements and does not /// use a `Vec`. -#[derive(Debug, Clone)] +#[derive(Clone)] pub struct ExactlyOneError<I> where I: Iterator, { - first_two: (Option<I::Item>, Option<I::Item>), + first_two: Option<Either<[I::Item; 2], I::Item>>, inner: I, } @@ -24,9 +30,17 @@ where I: Iterator, { /// Creates a new `ExactlyOneErr` iterator. - pub(crate) fn new(first_two: (Option<I::Item>, Option<I::Item>), inner: I) -> Self { + pub(crate) fn new(first_two: Option<Either<[I::Item; 2], I::Item>>, inner: I) -> Self { Self { first_two, inner } } + + fn additional_len(&self) -> usize { + match self.first_two { + Some(Either::Left(_)) => 2, + Some(Either::Right(_)) => 1, + None => 0, + } + } } impl<I> Iterator for ExactlyOneError<I> @@ -36,23 +50,61 @@ where type Item = I::Item; fn next(&mut self) -> Option<Self::Item> { - self.first_two - .0 - .take() - .or_else(|| self.first_two.1.take()) - .or_else(|| self.inner.next()) + match self.first_two.take() { + Some(Either::Left([first, second])) => { + self.first_two = Some(Either::Right(second)); + Some(first) + }, + Some(Either::Right(second)) => { + Some(second) + } + None => { + self.inner.next() + } + } } fn size_hint(&self) -> (usize, Option<usize>) { - let mut additional_len = 0; - if self.first_two.0.is_some() { - additional_len += 1; + size_hint::add_scalar(self.inner.size_hint(), self.additional_len()) + } +} + + +impl<I> ExactSizeIterator for ExactlyOneError<I> where I: ExactSizeIterator {} + +impl<I> Display for ExactlyOneError<I> + where I: Iterator, +{ + fn fmt(&self, f: &mut Formatter) -> FmtResult { + let additional = self.additional_len(); + if additional > 0 { + write!(f, "got at least 2 elements when exactly one was expected") + } else { + write!(f, "got zero elements when exactly one was expected") } - if self.first_two.1.is_some() { - additional_len += 1; + } +} + +impl<I> Debug for ExactlyOneError<I> + where I: Iterator + Debug, + I::Item: Debug, +{ + fn fmt(&self, f: &mut Formatter) -> FmtResult { + match &self.first_two { + Some(Either::Left([first, second])) => { + write!(f, "ExactlyOneError[First: {:?}, Second: {:?}, RemainingIter: {:?}]", first, second, self.inner) + }, + Some(Either::Right(second)) => { + write!(f, "ExactlyOneError[Second: {:?}, RemainingIter: {:?}]", second, self.inner) + } + None => { + write!(f, "ExactlyOneError[RemainingIter: {:?}]", self.inner) + } } - size_hint::add_scalar(self.inner.size_hint(), additional_len) } } -impl<I> ExactSizeIterator for ExactlyOneError<I> where I: ExactSizeIterator {} +#[cfg(feature = "use_std")] +impl<I> Error for ExactlyOneError<I> where I: Iterator + Debug, I::Item: Debug, {} + + |