add binary support in arrow-string

arrow-array/src/array/byte_view_array.rs

@@ -754,6 +754,20 @@ where
 pub type BinaryViewArray = GenericByteViewArray<BinaryViewType>;
 
 impl BinaryViewArray {
+    /// Returns true if all data within this array is ASCII
+    pub fn is_ascii(&self) -> bool {
+        // Alternative (but incorrect): directly check the underlying buffers
+        // (1) Our binary view might be sparse, i.e., a subset of the buffers,
+        //      so even if the buffer is not ascii, we can still be ascii.
+        // (2) It is quite difficult to know the range of each buffer (unlike BinaryArray)
+        // This means that this operation is quite expensive, shall we cache the result?
+        //  i.e. track `is_ascii` in the builder.
+        self.iter().all(|v| match v {
+            Some(v) => v.is_ascii(),
+            None => true,
+        })
+    }
+
     /// Convert the [`BinaryViewArray`] to [`StringViewArray`]
     /// If items not utf8 data, validate will fail and error returned.
     pub fn to_string_view(self) -> Result<StringViewArray, ArrowError> {

arrow-array/src/array/fixed_size_binary_array.rs

@@ -59,6 +59,16 @@ pub struct FixedSizeBinaryArray {
 }
 
 impl FixedSizeBinaryArray {
+    /// Returns true if all data within this array is ASCII
+    pub fn is_ascii(&self) -> bool {
+        // TODO - check if we can do similar to BinaryArray
+        //        as this is expensive
+        self.iter().all(|v| match v {
+            Some(v) => v.is_ascii(),
+            None => true,
+        })
+    }
+
     /// Create a new [`FixedSizeBinaryArray`] with `size` element size, panicking on failure
     ///
     /// # Panics