implement for compare

encodings/fastlanes/src/for/compare.rs

@@ -0,0 +1,44 @@
+use vortex_array::compute::{compare, CompareFn, Operator};
+use vortex_array::ArrayData;
+use vortex_error::VortexResult;
+
+use crate::{decompress, FoRArray, FoREncoding};
+
+impl CompareFn<FoRArray> for FoREncoding {
+    fn compare(
+        &self,
+        lhs: &FoRArray,
+        rhs: &ArrayData,
+        operator: Operator,
+    ) -> VortexResult<Option<ArrayData>> {
+        // this is cheap
+        let owned_lhs = lhs.clone();
+        let decompressed_lhs = decompress(owned_lhs)?;
+        compare(decompressed_lhs, rhs, operator).map(Some)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use vortex_array::array::PrimitiveArray;
+    use vortex_array::compute::{compare, Operator};
+    use vortex_array::validity::Validity;
+    use vortex_array::IntoArrayVariant;
+
+    use crate::for_compress;
+
+    #[test]
+    fn test_for_compare() {
+        let lhs = PrimitiveArray::from_vec(vec![1i32, 2, 3, 4, 5], Validity::AllValid);
+        let lhs = for_compress(&lhs).unwrap();
+        let rhs = PrimitiveArray::from_vec(vec![1i32, 2, 9, 4, 5], Validity::AllValid);
+        assert_eq!(
+            compare(lhs, rhs, Operator::Eq)
+                .unwrap()
+                .into_bool()
+                .unwrap()
+                .boolean_buffer(),
+            vec![true, true, false, true, true].into()
+        );
+    }
+}

encodings/fastlanes/src/for/compute.rs

@@ -2,8 +2,8 @@ use std::ops::AddAssign;
 
 use num_traits::{CheckedShl, CheckedShr, WrappingAdd, WrappingSub};
 use vortex_array::compute::{
-    filter, scalar_at, search_sorted, slice, take, ComputeVTable, FilterFn, FilterMask, ScalarAtFn,
-    SearchResult, SearchSortedFn, SearchSortedSide, SliceFn, TakeFn, TakeOptions,
+    filter, scalar_at, search_sorted, slice, take, CompareFn, ComputeVTable, FilterFn, FilterMask,
+    ScalarAtFn, SearchResult, SearchSortedFn, SearchSortedSide, SliceFn, TakeFn, TakeOptions,
 };
 use vortex_array::variants::PrimitiveArrayTrait;
 use vortex_array::{ArrayDType, ArrayData, IntoArrayData};
@@ -14,6 +14,10 @@ use vortex_scalar::{PValue, Scalar};
 use crate::{FoRArray, FoREncoding};
 
 impl ComputeVTable for FoREncoding {
+    fn compare_fn(&self) -> Option<&dyn CompareFn<ArrayData>> {
+        Some(self)
+    }
+
     fn filter_fn(&self) -> Option<&dyn FilterFn<ArrayData>> {
         Some(self)
     }

encodings/fastlanes/src/for/mod.rs

@@ -14,6 +14,7 @@ use vortex_dtype::DType;
 use vortex_error::{vortex_bail, VortexExpect as _, VortexResult};
 use vortex_scalar::{Scalar, ScalarValue};
 
+mod compare;
 mod compress;
 mod compute;