mbrobbel commented on code in PR #8543:
URL: https://github.com/apache/arrow-rs/pull/8543#discussion_r2401395596
##########
arrow-array/src/array/boolean_array.rs:
##########
@@ -436,11 +436,78 @@ impl<'a> BooleanArray {
}
}
-impl<Ptr: std::borrow::Borrow<Option<bool>>> FromIterator<Ptr> for
BooleanArray {
+/// An optional boolean value
+///
+/// This struct is used as an adapter when creating `BooleanArray` from an
iterator.
+/// `FromIterator` for `BooleanArray` takes an iterator where the elements can
be `into`
+/// this struct. So once implementing `From` or `Into` trait for a type, an
iterator of
+/// the type can be collected to `BooleanArray`.
+///
+/// See also [NativeAdapter](crate::array::NativeAdapter).
+#[derive(Debug)]
+pub struct BooleanAdapter {
+ /// Corresponding Rust native type if available
+ pub native: Option<bool>,
+}
+
+impl From<bool> for BooleanAdapter {
+ fn from(value: bool) -> Self {
+ BooleanAdapter {
+ native: Some(value),
+ }
+ }
+}
+
+impl From<&bool> for BooleanAdapter {
+ fn from(value: &bool) -> Self {
+ BooleanAdapter {
+ native: Some(*value),
+ }
+ }
+}
+
+impl From<Option<bool>> for BooleanAdapter {
+ fn from(value: Option<bool>) -> Self {
+ BooleanAdapter { native: value }
+ }
+}
+
+impl From<&Option<bool>> for BooleanAdapter {
+ fn from(value: &Option<bool>) -> Self {
+ BooleanAdapter { native: *value }
+ }
+}
+
+impl<Ptr: Into<BooleanAdapter>> FromIterator<Ptr> for BooleanArray {
fn from_iter<I: IntoIterator<Item = Ptr>>(iter: I) -> Self {
+ let vec = iter.into_iter().collect::<Vec<_>>();
+ unsafe {
+ // SAFETY: Vec iterator is trusted len
+ BooleanArray::from_trusted_len_iter(vec)
+ }
+ }
+}
+
+impl BooleanArray {
+ /// Creates a [`BooleanArray`] from an iterator of trusted length.
+ ///
+ /// # Safety
+ ///
+ /// The iterator must be
[`TrustedLen`](https://doc.rust-lang.org/std/iter/trait.TrustedLen.html).
+ /// I.e. that `size_hint().1` correctly reports its length.
+ ///
+ /// # Panics
+ ///
+ /// Panics if the iterator does not report an upper bound on `size_hint()`.
+ #[inline]
+ pub unsafe fn from_trusted_len_iter<I, P>(iter: I) -> Self
+ where
+ P: Into<BooleanAdapter>,
+ I: IntoIterator<Item = P>,
+ {
let iter = iter.into_iter();
let (_, data_len) = iter.size_hint();
- let data_len = data_len.expect("Iterator must be sized"); // panic if
no upper bound.
+ let data_len = data_len.expect("Iterator must be sized");
Review Comment:
Maybe we can use the stable
https://doc.rust-lang.org/std/iter/trait.ExactSizeIterator.html as bound?
##########
arrow-array/src/array/boolean_array.rs:
##########
@@ -436,11 +436,78 @@ impl<'a> BooleanArray {
}
}
-impl<Ptr: std::borrow::Borrow<Option<bool>>> FromIterator<Ptr> for
BooleanArray {
+/// An optional boolean value
+///
+/// This struct is used as an adapter when creating `BooleanArray` from an
iterator.
+/// `FromIterator` for `BooleanArray` takes an iterator where the elements can
be `into`
+/// this struct. So once implementing `From` or `Into` trait for a type, an
iterator of
+/// the type can be collected to `BooleanArray`.
+///
+/// See also [NativeAdapter](crate::array::NativeAdapter).
+#[derive(Debug)]
+pub struct BooleanAdapter {
Review Comment:
I think we can avoid exposing this?
```suggestion
struct BooleanAdapter {
```
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