diff options
Diffstat (limited to 'vendor/itertools-0.11.0/src/process_results_impl.rs')
-rw-r--r-- | vendor/itertools-0.11.0/src/process_results_impl.rs | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/vendor/itertools-0.11.0/src/process_results_impl.rs b/vendor/itertools-0.11.0/src/process_results_impl.rs new file mode 100644 index 000000000..713db4551 --- /dev/null +++ b/vendor/itertools-0.11.0/src/process_results_impl.rs @@ -0,0 +1,68 @@ +#[cfg(doc)] +use crate::Itertools; + +/// An iterator that produces only the `T` values as long as the +/// inner iterator produces `Ok(T)`. +/// +/// Used by [`process_results`](crate::process_results), see its docs +/// for more information. +#[must_use = "iterator adaptors are lazy and do nothing unless consumed"] +#[derive(Debug)] +pub struct ProcessResults<'a, I, E: 'a> { + error: &'a mut Result<(), E>, + iter: I, +} + +impl<'a, I, T, E> Iterator for ProcessResults<'a, I, E> + where I: Iterator<Item = Result<T, E>> +{ + type Item = T; + + fn next(&mut self) -> Option<Self::Item> { + match self.iter.next() { + Some(Ok(x)) => Some(x), + Some(Err(e)) => { + *self.error = Err(e); + None + } + None => None, + } + } + + fn size_hint(&self) -> (usize, Option<usize>) { + (0, self.iter.size_hint().1) + } + + fn fold<B, F>(mut self, init: B, mut f: F) -> B + where + Self: Sized, + F: FnMut(B, Self::Item) -> B, + { + let error = self.error; + self.iter + .try_fold(init, |acc, opt| match opt { + Ok(x) => Ok(f(acc, x)), + Err(e) => { + *error = Err(e); + Err(acc) + } + }) + .unwrap_or_else(|e| e) + } +} + +/// “Lift” a function of the values of an iterator so that it can process +/// an iterator of `Result` values instead. +/// +/// [`IntoIterator`] enabled version of [`Itertools::process_results`]. +pub fn process_results<I, F, T, E, R>(iterable: I, processor: F) -> Result<R, E> + where I: IntoIterator<Item = Result<T, E>>, + F: FnOnce(ProcessResults<I::IntoIter, E>) -> R +{ + let iter = iterable.into_iter(); + let mut error = Ok(()); + + let result = processor(ProcessResults { error: &mut error, iter }); + + error.map(|_| result) +} |