Add Iterator subtraits

pgrx-tests/src/tests/array_borrowed.rs

@@ -22,7 +22,7 @@ fn borrow_sum_array_i32(values: &FlatArray<'_, i32>) -> i32 {
     // we implement it this way so we can trap an overflow (as we have a test for this) and
     // catch it correctly in both --debug and --release modes
     let mut sum = 0_i32;
-    for v in values.iter() {
+    for v in values {
         let v = v.into_option().copied().unwrap_or(0);
         let (val, overflow) = sum.overflowing_add(v);
         if overflow {

pgrx/src/array.rs

@@ -20,6 +20,7 @@ use crate::toast::{Toast, Toasty};
 use crate::{layout, pg_sys, varlena};
 use bitvec::ptr::{self as bitptr, BitPtr, BitPtrError, Const, Mut};
 use bitvec::slice::{self as bitslice, BitSlice};
+use core::iter::{ExactSizeIterator, FusedIterator};
 use core::marker::PhantomData;
 use core::ptr::{self, NonNull};
 use core::{ffi, mem, slice};
@@ -257,6 +258,20 @@ where
     }
 }
 
+impl<'arr, 'mcx, T> IntoIterator for &'arr FlatArray<'mcx, T>
+where
+    T: ?Sized + BorrowDatum,
+{
+    type IntoIter = ArrayIter<'arr, T>;
+    type Item = Nullable<&'arr T>;
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<'arr, T> ExactSizeIterator for ArrayIter<'arr, T> where T: ?Sized + BorrowDatum {}
+impl<'arr, T> FusedIterator for ArrayIter<'arr, T> where T: ?Sized + BorrowDatum {}
+
 /**
 An aligned, dereferenceable `NonNull<ArrayType>` with low-level accessors.