Adds a GetItem operator array

vortex-array/src/compute/arrays/get_item.rs

@@ -0,0 +1,309 @@
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-FileCopyrightText: Copyright the Vortex contributors
+
+use std::hash::{Hash, Hasher};
+
+use vortex_compute::mask::MaskValidity;
+use vortex_dtype::{DType, FieldName};
+use vortex_error::{VortexResult, vortex_bail, vortex_err};
+use vortex_vector::VectorOps;
+
+use crate::execution::{BatchKernelRef, BindCtx, kernel};
+use crate::stats::{ArrayStats, StatsSetRef};
+use crate::vtable::{ArrayVTable, NotSupported, OperatorVTable, VTable, VisitorVTable};
+use crate::{
+    Array, ArrayBufferVisitor, ArrayChildVisitor, ArrayEq, ArrayHash, ArrayRef, EncodingId,
+    EncodingRef, Precision, vtable,
+};
+
+vtable!(GetItem);
+
+/// An array that extracts the given field from a Struct array.
+///
+/// The validity of the field is intersected with the validity of the parent Struct array.
+#[derive(Debug, Clone)]
+pub struct GetItemArray {
+    child: ArrayRef,
+    field: FieldName,
+    dtype: DType,
+    stats: ArrayStats,
+}
+
+impl GetItemArray {
+    /// Create a new get_item array.
+    pub fn try_new(child: ArrayRef, field: FieldName) -> VortexResult<Self> {
+        let DType::Struct(fields, _) = child.dtype() else {
+            vortex_bail!(
+                "GetItem can only be applied to Struct arrays, got {}",
+                child.dtype()
+            );
+        };
+
+        let Some(dtype) = fields.field(&field) else {
+            vortex_bail!("Field '{}' does not exist in Struct array", field);
+        };
+
+        // Make the field nullable if the parent struct is nullable
+        let dtype = dtype.with_nullability(dtype.nullability() | child.dtype().nullability());
+
+        Ok(Self {
+            child,
+            field,
+            dtype,
+            stats: ArrayStats::default(),
+        })
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct GetItemEncoding;
+
+impl VTable for GetItemVTable {
+    type Array = GetItemArray;
+    type Encoding = GetItemEncoding;
+    type ArrayVTable = Self;
+    type CanonicalVTable = NotSupported;
+    type OperationsVTable = NotSupported;
+    type ValidityVTable = NotSupported;
+    type VisitorVTable = Self;
+    type ComputeVTable = NotSupported;
+    type EncodeVTable = NotSupported;
+    type SerdeVTable = NotSupported;
+    type OperatorVTable = Self;
+
+    fn id(_encoding: &Self::Encoding) -> EncodingId {
+        EncodingId::from("vortex.get_item")
+    }
+
+    fn encoding(_array: &Self::Array) -> EncodingRef {
+        EncodingRef::from(GetItemEncoding.as_ref())
+    }
+}
+
+impl ArrayVTable<GetItemVTable> for GetItemVTable {
+    fn len(array: &GetItemArray) -> usize {
+        array.child.len()
+    }
+
+    fn dtype(array: &GetItemArray) -> &DType {
+        &array.dtype
+    }
+
+    fn stats(array: &GetItemArray) -> StatsSetRef<'_> {
+        array.stats.to_ref(array.as_ref())
+    }
+
+    fn array_hash<H: Hasher>(array: &GetItemArray, state: &mut H, precision: Precision) {
+        array.child.array_hash(state, precision);
+        array.field.hash(state);
+    }
+
+    fn array_eq(array: &GetItemArray, other: &GetItemArray, precision: Precision) -> bool {
+        array.child.array_eq(&other.child, precision) && array.field == other.field
+    }
+}
+
+impl VisitorVTable<GetItemVTable> for GetItemVTable {
+    fn visit_buffers(_array: &GetItemArray, _visitor: &mut dyn ArrayBufferVisitor) {
+        // No buffers
+    }
+
+    fn visit_children(array: &GetItemArray, visitor: &mut dyn ArrayChildVisitor) {
+        visitor.visit_child("struct", array.child.as_ref());
+    }
+}
+
+impl OperatorVTable<GetItemVTable> for GetItemVTable {
+    fn bind(
+        array: &GetItemArray,
+        selection: Option<&ArrayRef>,
+        ctx: &mut dyn BindCtx,
+    ) -> VortexResult<BatchKernelRef> {
+        let child = ctx.bind(&array.child, selection)?;
+
+        // Find the index of the field in the struct
+        let idx = array
+            .child
+            .dtype()
+            .as_struct_fields()
+            .find(&array.field)
+            .ok_or_else(|| vortex_err!("Field '{}' does not exist in Struct array", array.field))?;
+
+        Ok(kernel(move || {
+            let struct_ = child.execute()?.into_struct();
+
+            // We must intersect the validity with that of the parent struct
+            let field = struct_.fields()[idx].clone();
+            let field = MaskValidity::mask_validity(field, struct_.validity());
+
+            Ok(field)
+        }))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use vortex_buffer::{bitbuffer, buffer};
+    use vortex_dtype::{FieldNames, Nullability, PTypeDowncast};
+    use vortex_vector::VectorOps;
+
+    use crate::arrays::{BoolArray, PrimitiveArray, StructArray};
+    use crate::compute::arrays::get_item::GetItemArray;
+    use crate::validity::Validity;
+    use crate::{ArrayOperator, IntoArray};
+
+    #[test]
+    fn test_get_item_basic() {
+        // Create a non-nullable struct with non-nullable fields
+        let int_field = PrimitiveArray::from_iter([10i32, 20, 30, 40]);
+        let bool_field = BoolArray::from_iter([true, false, true, false]);
+
+        let struct_array = StructArray::try_new(
+            FieldNames::from(["numbers", "flags"]),
+            vec![int_field.into_array(), bool_field.into_array()],
+            4,
+            Validity::NonNullable,
+        )
+        .unwrap()
+        .into_array();
+
+        // Extract the "numbers" field
+        let get_item = GetItemArray::try_new(struct_array, "numbers".into())
+            .unwrap()
+            .into_array();
+
+        // Verify the dtype is non-nullable
+        assert_eq!(get_item.dtype().nullability(), Nullability::NonNullable);
+
+        // Execute and verify the values
+        let result = get_item.execute().unwrap().into_primitive().into_i32();
+        assert_eq!(result.elements(), &buffer![10i32, 20, 30, 40]);
+    }
+
+    #[test]
+    fn test_get_item_nullable_struct_nonnullable_field() {
+        // Create a nullable struct with non-nullable field
+        // The result should be nullable because the struct is nullable
+        let int_field = PrimitiveArray::from_iter([10i32, 20, 30, 40]);
+
+        let struct_array = StructArray::try_new(
+            FieldNames::from(["numbers"]),
+            vec![int_field.into_array()],
+            4,
+            Validity::from_iter([true, false, true, false]),
+        )
+        .unwrap()
+        .into_array();
+
+        // Extract the "numbers" field
+        let get_item = GetItemArray::try_new(struct_array, "numbers".into())
+            .unwrap()
+            .into_array();
+
+        // The dtype should be nullable even though the field itself is non-nullable
+        assert_eq!(get_item.dtype().nullability(), Nullability::Nullable);
+
+        // Execute and verify values and validity
+        let result = get_item.execute().unwrap().into_primitive().into_i32();
+        assert_eq!(result.elements(), &buffer![10i32, 20, 30, 40]);
+
+        // Check that validity was properly intersected
+        // Elements at indices 1 and 3 should be null due to struct validity
+        assert_eq!(result.validity().to_bit_buffer(), bitbuffer![1 0 1 0]);
+    }
+
+    #[test]
+    fn test_get_item_with_selection() {
+        // Create a struct with multiple fields
+        let int_field = PrimitiveArray::from_iter([10i32, 20, 30, 40, 50, 60]);
+        let bool_field = BoolArray::from_iter([true, false, true, false, true, false]);
+
+        let struct_array = StructArray::try_new(
+            FieldNames::from(["numbers", "flags"]),
+            vec![int_field.into_array(), bool_field.into_array()],
+            6,
+            Validity::from_iter([true, true, false, true, true, false]),
+        )
+        .unwrap()
+        .into_array();
+
+        // Extract the "numbers" field
+        let get_item = GetItemArray::try_new(struct_array, "numbers".into())
+            .unwrap()
+            .into_array();
+
+        // Apply selection mask [1 0 1 0 1 0] => select indices 0, 2, 4
+        let selection = bitbuffer![1 0 1 0 1 0].into_array();
+        let result = get_item
+            .execute_with_selection(Some(&selection))
+            .unwrap()
+            .into_primitive()
+            .into_i32();
+
+        // Should have 3 elements: indices 0, 2, 4
+        assert_eq!(result.len(), 3);
+        assert_eq!(result.elements(), &buffer![10i32, 30, 50]);
+
+        // Check validity: index 0 is valid, index 2 is null (struct), index 4 is valid
+        assert_eq!(result.validity().to_bit_buffer(), bitbuffer![1 0 1]);
+    }
+
+    #[test]
+    fn test_get_item_intersects_validity() {
+        // Test that field validity is intersected with struct validity
+        // Field has nulls at indices 1, 3
+        let int_field =
+            PrimitiveArray::from_option_iter([Some(10i32), None, Some(30), None, Some(50)]);
+
+        // Struct has nulls at indices 2, 4
+        let struct_array = StructArray::try_new(
+            FieldNames::from(["values"]),
+            vec![int_field.into_array()],
+            5,
+            Validity::from_iter([true, true, false, true, false]),
+        )
+        .unwrap()
+        .into_array();
+
+        let get_item = GetItemArray::try_new(struct_array, "values".into())
+            .unwrap()
+            .into_array();
+
+        let result = get_item.execute().unwrap().into_primitive().into_i32();
+
+        // Verify that nulls are correctly combined:
+        // Index 0: valid (both valid)
+        // Index 1: null (field null)
+        // Index 2: null (struct null)
+        // Index 3: null (field null)
+        // Index 4: null (struct null)
+        assert_eq!(result.validity().to_bit_buffer(), bitbuffer![1 0 0 0 0]);
+    }
+
+    #[test]
+    fn test_get_item_bool_field() {
+        // Test extracting a boolean field
+        let bool_field = BoolArray::from_iter([true, false, true, false]);
+
+        let struct_array = StructArray::try_new(
+            FieldNames::from(["flags"]),
+            vec![bool_field.into_array()],
+            4,
+            Validity::from_iter([true, false, true, true]),
+        )
+        .unwrap()
+        .into_array();
+
+        let get_item = GetItemArray::try_new(struct_array, "flags".into())
+            .unwrap()
+            .into_array();
+
+        let result = get_item.execute().unwrap().into_bool();
+
+        // Verify values
+        assert_eq!(result.bits(), &bitbuffer![1 0 1 0]);
+
+        // Verify validity (index 1 should be null from struct)
+        assert_eq!(result.validity().to_bit_buffer(), bitbuffer![1 0 1 1]);
+    }
+}

vortex-array/src/compute/arrays/is_not_null.rs

@@ -52,7 +52,7 @@ impl VTable for IsNotNullVTable {
     type OperatorVTable = Self;
 
     fn id(_encoding: &Self::Encoding) -> EncodingId {
-        EncodingId::from("vortex.is_null")
+        EncodingId::from("vortex.is_not_null")
     }
 
     fn encoding(_array: &Self::Array) -> EncodingRef {
@@ -62,7 +62,7 @@ impl VTable for IsNotNullVTable {
 
 impl ArrayVTable<IsNotNullVTable> for IsNotNullVTable {
     fn len(array: &IsNotNullArray) -> usize {
-        array.len()
+        array.child.len()
     }
 
     fn dtype(_array: &IsNotNullArray) -> &DType {

vortex-array/src/compute/arrays/is_null.rs

@@ -63,7 +63,7 @@ impl VTable for IsNullVTable {
 
 impl ArrayVTable<IsNullVTable> for IsNullVTable {
     fn len(array: &IsNullArray) -> usize {
-        array.len()
+        array.child.len()
     }
 
     fn dtype(_array: &IsNullArray) -> &DType {

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

@@ -2,6 +2,7 @@
 // SPDX-FileCopyrightText: Copyright the Vortex contributors
 
 pub mod arithmetic;
+mod get_item;
 pub mod is_not_null;
 pub mod is_null;
 pub mod logical;

vortex-dtype/src/dtype.rs

@@ -369,6 +369,18 @@ impl DType {
         }
     }
 
+    /// Returns the [`StructFields`] from a struct [`DType`].
+    ///
+    /// # Panics
+    ///
+    /// If the [`DType`] is not a struct.
+    pub fn as_struct_fields(&self) -> &StructFields {
+        if let Struct(f, _) = self {
+            return f;
+        }
+        vortex_panic!("DType is not a Struct")
+    }
+
     /// Get the `StructDType` if `self` is a `StructDType`, otherwise `None`
     pub fn as_struct_fields_opt(&self) -> Option<&StructFields> {
         if let Struct(f, _) = self {

vortex-vector/src/struct_/vector.rs

@@ -154,7 +154,7 @@ impl VectorOps for StructVector {
             }
         };
 
-        // Convert all of the remaining fields to mutable, if possible.
+        // Convert all the remaining fields to mutable, if possible.
         let mut mutable_fields = Vec::with_capacity(fields.len());
         let mut fields_iter = fields.into_iter();