askoa commented on code in PR #3603:
URL: https://github.com/apache/arrow-rs/pull/3603#discussion_r1092863125
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arrow-array/src/array/run_array.rs:
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@@ -274,15 +296,191 @@ pub type Int32RunArray = RunArray<Int32Type>;
/// ```
pub type Int64RunArray = RunArray<Int64Type>;
+/// A strongly-typed wrapper around a [`RunArray`] that implements
[`ArrayAccessor`]
+/// and [`IntoIterator`] allowing fast access to its elements
+///
+/// ```
+/// use arrow_array::{RunArray, StringArray, types::Int32Type};
+///
+/// let orig = ["a", "b", "a", "b"];
+/// let ree_array = RunArray::<Int32Type>::from_iter(orig);
+///
+/// // `TypedRunArray` allows you to access the values directly
+/// let typed = ree_array.downcast_ref::<StringArray>().unwrap();
+///
+/// for (maybe_val, orig) in typed.into_iter().zip(orig) {
+/// assert_eq!(maybe_val.unwrap(), orig)
+/// }
+/// ```
+pub struct TypedRunArray<'a, R: RunEndIndexType, V> {
+ /// The run array
+ run_array: &'a RunArray<R>,
+
+ /// The values of the run_array
+ values: &'a V,
+}
+
+// Manually implement `Clone` to avoid `V: Clone` type constraint
+impl<'a, R: RunEndIndexType, V> Clone for TypedRunArray<'a, R, V> {
+ fn clone(&self) -> Self {
+ Self {
+ run_array: self.run_array,
+ values: self.values,
+ }
+ }
+}
+
+impl<'a, R: RunEndIndexType, V> Copy for TypedRunArray<'a, R, V> {}
+
+impl<'a, R: RunEndIndexType, V> std::fmt::Debug for TypedRunArray<'a, R, V> {
+ fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+ writeln!(f, "TypedRunArray({:?})", self.run_array)
+ }
+}
+
+impl<'a, R: RunEndIndexType, V> TypedRunArray<'a, R, V> {
+ /// Returns the run_ends of this [`TypedRunArray`]
+ pub fn run_ends(&self) -> &'a PrimitiveArray<R> {
+ self.run_array.run_ends()
+ }
+
+ /// Returns the values of this [`TypedRunArray`]
+ pub fn values(&self) -> &'a V {
+ self.values
+ }
+
+ /// Returns index to the physcial array for the given index to the logical
array.
+ /// Performs a binary search on the run_ends array for the input index.
+ #[inline]
+ pub fn get_physical_index(&self, logical_index: usize) -> Option<usize> {
+ if logical_index >= self.run_array.len() {
+ return None;
+ }
+ let mut st: usize = 0;
Review Comment:
To use `binary_search_by` a custom `Ordering` has to be implemented. Two
values (`i` and `i-1`) has to be accessed to determine
`std::cmp::Ordering::Equal`. I am not sure what'll happen if `Equal` was never
returned in custom `Ordering`. I did not spend lot of time on it because did
not see the benefits.
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