Share fixed-width compute kernels

Signed-off-by: Connor Tsui <connor.tsui20@gmail.com>

Author: connortsui20

vortex-array/src/arrays/decimal/compute/fixed_width.rs

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright the Vortex contributors
+
+use vortex_buffer::ByteBuffer;
+use vortex_error::VortexResult;
+use vortex_error::vortex_ensure;
+use vortex_error::vortex_err;
+
+use crate::array::ArrayView;
+use crate::arrays::Decimal;
+use crate::arrays::DecimalArray;
+use crate::arrays::fixed_width::FixedWidthArray;
+use crate::buffer::BufferHandle;
+use crate::validity::Validity;
+
+impl FixedWidthArray for Decimal {
+    fn byte_width(array: ArrayView<'_, Self>) -> usize {
+        array.values_type().byte_width()
+    }
+
+    fn values(array: ArrayView<'_, Self>) -> ByteBuffer {
+        array.buffer_handle().to_host_sync()
+    }
+
+    fn with_values(
+        array: ArrayView<'_, Self>,
+        values: ByteBuffer,
+        len: usize,
+        validity: Validity,
+    ) -> VortexResult<DecimalArray> {
+        let expected_len = len
+            .checked_mul(array.values_type().byte_width())
+            .ok_or_else(|| vortex_err!("Decimal values buffer length overflows usize"))?;
+        vortex_ensure!(
+            values.len() == expected_len,
+            "Decimal values buffer length does not match output length"
+        );
+        DecimalArray::try_new_handle(
+            BufferHandle::new_host(values),
+            array.values_type(),
+            array.decimal_dtype(),
+            validity,
+        )
+    }
+}

vortex-array/src/arrays/decimal/compute/mod.rs

@@ -4,9 +4,9 @@
 mod between;
 mod cast;
 mod fill_null;
+mod fixed_width;
 mod mask;
 pub mod rules;
-mod take;
 
 #[cfg(test)]
 mod tests {