From 7146a7ab031c928ce7594e1747d5447b5e5fbf26 Mon Sep 17 00:00:00 2001
From: Raphael Taylor-Davies <r.taylordavies@googlemail.com>
Date: Wed, 8 May 2024 07:45:03 +0100
Subject: [PATCH] Add ByteView::try_new

---
 arrow-array/src/array/byte_view_array.rs | 16 +++++++---------
 arrow-data/src/byte_view.rs              | 14 +++++++++++++-
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/arrow-array/src/array/byte_view_array.rs b/arrow-array/src/array/byte_view_array.rs
index 79f2d47587a..32ca911ac0f 100644
--- a/arrow-array/src/array/byte_view_array.rs
+++ b/arrow-array/src/array/byte_view_array.rs
@@ -237,15 +237,13 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
     /// Caller is responsible for ensuring that the index is within the bounds of the array
     pub unsafe fn value_unchecked(&self, idx: usize) -> &T::Native {
         let v = self.views.get_unchecked(idx);
-        let len = *v as u32;
-        let b = if len <= 12 {
-            let ptr = self.views.as_ptr() as *const u8;
-            std::slice::from_raw_parts(ptr.add(idx * 16 + 4), len as usize)
-        } else {
-            let view = ByteView::from(*v);
-            let data = self.buffers.get_unchecked(view.buffer_index as usize);
-            let offset = view.offset as usize;
-            data.get_unchecked(offset..offset + len as usize)
+        let b = match ByteView::try_new(v) {
+            Ok(view) => {
+                let data = self.buffers.get_unchecked(view.buffer_index as usize);
+                let offset = view.offset as usize;
+                data.get_unchecked(offset..offset + view.length as usize)
+            }
+            Err(b) => b,
         };
         T::Native::from_bytes_unchecked(b)
     }
diff --git a/arrow-data/src/byte_view.rs b/arrow-data/src/byte_view.rs
index b8b1731ac60..ac7df4ff85d 100644
--- a/arrow-data/src/byte_view.rs
+++ b/arrow-data/src/byte_view.rs
@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use arrow_buffer::Buffer;
+use arrow_buffer::{Buffer, ToByteSlice};
 use arrow_schema::ArrowError;
 
 #[derive(Debug, Copy, Clone, Default)]
@@ -32,6 +32,18 @@ pub struct ByteView {
 }
 
 impl ByteView {
+    /// Try to create a [`ByteView`] from the provided `v`
+    ///
+    /// If `v` instead contains the binary data inline, returns an `Err` containing it
+    #[inline]
+    pub fn try_new(v: &u128) -> Result<Self, &[u8]> {
+        let len = *v as u32;
+        match len <= 12 {
+            true => Err(&v.to_byte_slice()[4..4 + len as usize]),
+            false => Ok(Self::from(*v)),
+        }
+    }
+
     #[inline(always)]
     pub fn as_u128(self) -> u128 {
         (self.length as u128)