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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/07/22 16:54:17 UTC
[GitHub] [arrow-rs] viirya commented on a diff in pull request #2133: Add ArrayAccessor trait, remove duplication in array iterators (#1948)
viirya commented on code in PR #2133:
URL: https://github.com/apache/arrow-rs/pull/2133#discussion_r927835847
##########
arrow/src/array/iterator.rs:
##########
@@ -94,304 +95,14 @@ impl<'a, T: ArrowPrimitiveType> std::iter::DoubleEndedIterator for PrimitiveIter
}
/// all arrays have known size.
-impl<'a, T: ArrowPrimitiveType> std::iter::ExactSizeIterator for PrimitiveIter<'a, T> {}
-
-/// an iterator that returns Some(bool) or None.
-// Note: This implementation is based on std's [Vec]s' [IntoIter].
-#[derive(Debug)]
-pub struct BooleanIter<'a> {
- array: &'a BooleanArray,
- current: usize,
- current_end: usize,
-}
-
-impl<'a> BooleanIter<'a> {
- /// create a new iterator
- pub fn new(array: &'a BooleanArray) -> Self {
- BooleanIter {
- array,
- current: 0,
- current_end: array.len(),
- }
- }
-}
-
-impl<'a> std::iter::Iterator for BooleanIter<'a> {
- type Item = Option<bool>;
-
- fn next(&mut self) -> Option<Self::Item> {
- if self.current == self.current_end {
- None
- } else if self.array.is_null(self.current) {
- self.current += 1;
- Some(None)
- } else {
- let old = self.current;
- self.current += 1;
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(Some(self.array.value_unchecked(old))) }
- }
- }
+impl<T: ArrayAccessor> ExactSizeIterator for ArrayIter<T> {}
- fn size_hint(&self) -> (usize, Option<usize>) {
- (
- self.array.len() - self.current,
- Some(self.array.len() - self.current),
- )
- }
-}
-
-impl<'a> std::iter::DoubleEndedIterator for BooleanIter<'a> {
- fn next_back(&mut self) -> Option<Self::Item> {
- if self.current_end == self.current {
- None
- } else {
- self.current_end -= 1;
- Some(if self.array.is_null(self.current_end) {
- None
- } else {
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(self.array.value_unchecked(self.current_end)) }
- })
- }
- }
-}
-
-/// all arrays have known size.
-impl<'a> std::iter::ExactSizeIterator for BooleanIter<'a> {}
-
-/// an iterator that returns `Some(&str)` or `None`, for string arrays
-#[derive(Debug)]
-pub struct GenericStringIter<'a, T>
-where
- T: OffsetSizeTrait,
-{
- array: &'a GenericStringArray<T>,
- current: usize,
- current_end: usize,
-}
-
-impl<'a, T: OffsetSizeTrait> GenericStringIter<'a, T> {
- /// create a new iterator
- pub fn new(array: &'a GenericStringArray<T>) -> Self {
- GenericStringIter::<T> {
- array,
- current: 0,
- current_end: array.len(),
- }
- }
-}
-
-impl<'a, T: OffsetSizeTrait> std::iter::Iterator for GenericStringIter<'a, T> {
- type Item = Option<&'a str>;
-
- fn next(&mut self) -> Option<Self::Item> {
- let i = self.current;
- if i >= self.current_end {
- None
- } else if self.array.is_null(i) {
- self.current += 1;
- Some(None)
- } else {
- self.current += 1;
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(Some(self.array.value_unchecked(i))) }
- }
- }
-
- fn size_hint(&self) -> (usize, Option<usize>) {
- (
- self.current_end - self.current,
- Some(self.current_end - self.current),
- )
- }
-}
-
-impl<'a, T: OffsetSizeTrait> std::iter::DoubleEndedIterator for GenericStringIter<'a, T> {
- fn next_back(&mut self) -> Option<Self::Item> {
- if self.current_end == self.current {
- None
- } else {
- self.current_end -= 1;
- Some(if self.array.is_null(self.current_end) {
- None
- } else {
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(self.array.value_unchecked(self.current_end)) }
- })
- }
- }
-}
-
-/// all arrays have known size.
-impl<'a, T: OffsetSizeTrait> std::iter::ExactSizeIterator for GenericStringIter<'a, T> {}
-
-/// an iterator that returns `Some(&[u8])` or `None`, for binary arrays
-#[derive(Debug)]
-pub struct GenericBinaryIter<'a, T>
-where
- T: OffsetSizeTrait,
-{
- array: &'a GenericBinaryArray<T>,
- current: usize,
- current_end: usize,
-}
-
-impl<'a, T: OffsetSizeTrait> GenericBinaryIter<'a, T> {
- /// create a new iterator
- pub fn new(array: &'a GenericBinaryArray<T>) -> Self {
- GenericBinaryIter::<T> {
- array,
- current: 0,
- current_end: array.len(),
- }
- }
-}
-
-impl<'a, T: OffsetSizeTrait> std::iter::Iterator for GenericBinaryIter<'a, T> {
- type Item = Option<&'a [u8]>;
-
- fn next(&mut self) -> Option<Self::Item> {
- let i = self.current;
- if i >= self.current_end {
- None
- } else if self.array.is_null(i) {
- self.current += 1;
- Some(None)
- } else {
- self.current += 1;
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(Some(self.array.value_unchecked(i))) }
- }
- }
-
- fn size_hint(&self) -> (usize, Option<usize>) {
- (
- self.current_end - self.current,
- Some(self.current_end - self.current),
- )
- }
-}
-
-impl<'a, T: OffsetSizeTrait> std::iter::DoubleEndedIterator for GenericBinaryIter<'a, T> {
- fn next_back(&mut self) -> Option<Self::Item> {
- if self.current_end == self.current {
- None
- } else {
- self.current_end -= 1;
- Some(if self.array.is_null(self.current_end) {
- None
- } else {
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(self.array.value_unchecked(self.current_end)) }
- })
- }
- }
-}
-
-/// all arrays have known size.
-impl<'a, T: OffsetSizeTrait> std::iter::ExactSizeIterator for GenericBinaryIter<'a, T> {}
-
-#[derive(Debug)]
-pub struct GenericListArrayIter<'a, S>
-where
- S: OffsetSizeTrait,
-{
- array: &'a GenericListArray<S>,
- current: usize,
- current_end: usize,
-}
-
-impl<'a, S: OffsetSizeTrait> GenericListArrayIter<'a, S> {
- pub fn new(array: &'a GenericListArray<S>) -> Self {
- GenericListArrayIter::<S> {
- array,
- current: 0,
- current_end: array.len(),
- }
- }
-}
-
-impl<'a, S: OffsetSizeTrait> std::iter::Iterator for GenericListArrayIter<'a, S> {
- type Item = Option<ArrayRef>;
-
- fn next(&mut self) -> Option<Self::Item> {
- let i = self.current;
- if i >= self.current_end {
- None
- } else if self.array.is_null(i) {
- self.current += 1;
- Some(None)
- } else {
- self.current += 1;
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(Some(self.array.value_unchecked(i))) }
- }
- }
-
- fn size_hint(&self) -> (usize, Option<usize>) {
- (
- self.current_end - self.current,
- Some(self.current_end - self.current),
- )
- }
-}
-
-impl<'a, S: OffsetSizeTrait> std::iter::DoubleEndedIterator
- for GenericListArrayIter<'a, S>
-{
- fn next_back(&mut self) -> Option<Self::Item> {
- if self.current_end == self.current {
- None
- } else {
- self.current_end -= 1;
- Some(if self.array.is_null(self.current_end) {
- None
- } else {
- // Safety:
- // we just checked bounds in `self.current_end == self.current`
- // this is safe on the premise that this struct is initialized with
- // current = array.len()
- // and that current_end is ever only decremented
- unsafe { Some(self.array.value_unchecked(self.current_end)) }
- })
- }
- }
-}
-
-/// all arrays have known size.
-impl<'a, S: OffsetSizeTrait> std::iter::ExactSizeIterator
- for GenericListArrayIter<'a, S>
-{
-}
+/// an iterator that returns Some(T) or None, that can be used on any PrimitiveArray
+pub type PrimitiveIter<'a, T> = ArrayIter<&'a PrimitiveArray<T>>;
+pub type BooleanIter<'a> = ArrayIter<&'a BooleanArray>;
+pub type GenericStringIter<'a, T> = ArrayIter<&'a GenericStringArray<T>>;
+pub type GenericBinaryIter<'a, T> = ArrayIter<&'a GenericBinaryArray<T>>;
+pub type GenericListArrayIter<'a, O> = ArrayIter<&'a GenericListArray<O>>;
Review Comment:
👍 Nice
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