scovich commented on code in PR #7704:
URL: https://github.com/apache/arrow-rs/pull/7704#discussion_r2155455584
##########
parquet-variant/src/utils.rs:
##########
@@ -74,28 +75,37 @@ pub(crate) fn string_from_slice(slice: &[u8], range:
Range<usize>) -> Result<&st
/// * `Ok(Ok(index))` - Element found at the given index
/// * `Ok(Err(index))` - Element not found, but would be inserted at the given
index
/// * `Err(e)` - Key extraction failed with error `e`
-pub(crate) fn try_binary_search_by<T, K, E, F>(
- slice: &[T],
+pub(crate) fn try_binary_search_range_by<K, E, F>(
+ range: Range<usize>,
target: &K,
mut key_extractor: F,
) -> Result<Result<usize, usize>, E>
where
K: Ord,
- F: FnMut(&T) -> Result<K, E>,
+ F: FnMut(usize) -> Result<K, E>,
{
- let mut left = 0;
- let mut right = slice.len();
+ let Range { mut start, mut end } = range;
- while left < right {
- let mid = (left + right) / 2;
- let key = key_extractor(&slice[mid])?;
+ while start < end {
+ let mid = start + (end - start) / 2;
+ let key = key_extractor(mid)?;
match key.cmp(target) {
std::cmp::Ordering::Equal => return Ok(Ok(mid)),
- std::cmp::Ordering::Greater => right = mid,
- std::cmp::Ordering::Less => left = mid + 1,
+ std::cmp::Ordering::Greater => end = mid,
+ std::cmp::Ordering::Less => start = mid + 1,
}
}
- Ok(Err(left))
+ Ok(Err(start))
+}
+
+/// Attempts to prove a fallible iterator is actually infallible in practice,
by consuming every
+/// element and returning the first error (if any).
+pub(crate) fn validate_fallible_iterator<T, E>(
+ mut it: impl Iterator<Item = Result<T, E>>,
+) -> Result<(), E> {
+ // NOTE: It should really be `let None = ...`, but the compiler can't
prove that.
+ let _ = it.find(Result::is_err).transpose()?;
+ Ok(())
Review Comment:
Ah, I _knew_ there must be some magic incatation for that, but I couldn't
figure it out.
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