vortex_array/arrays/constant/

canonical.rs

// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright the Vortex contributors

use std::sync::Arc;

use arrow_buffer::BooleanBuffer;
use vortex_buffer::{Buffer, buffer};
use vortex_dtype::{DType, Nullability, PType, match_each_native_ptype};
use vortex_error::VortexExpect;
use vortex_scalar::{
    BinaryScalar, BoolScalar, DecimalValue, ExtScalar, ListScalar, Scalar, ScalarValue,
    StructScalar, Utf8Scalar, match_each_decimal_value, match_each_decimal_value_type,
};

use crate::arrays::constant::ConstantArray;
use crate::arrays::primitive::PrimitiveArray;
use crate::arrays::{
    BinaryView, BoolArray, ConstantVTable, DecimalArray, ExtensionArray, ListArray, NullArray,
    StructArray, VarBinViewArray, smallest_storage_type,
};
use crate::builders::builder_with_capacity;
use crate::validity::Validity;
use crate::vtable::CanonicalVTable;
use crate::{Canonical, IntoArray};

impl CanonicalVTable<ConstantVTable> for ConstantVTable {
    fn canonicalize(array: &ConstantArray) -> Canonical {
        let scalar = array.scalar();

        let validity = match array.dtype().nullability() {
            Nullability::NonNullable => Validity::NonNullable,
            Nullability::Nullable => match scalar.is_null() {
                true => Validity::AllInvalid,
                false => Validity::AllValid,
            },
        };

        match array.dtype() {
            DType::Null => Canonical::Null(NullArray::new(array.len())),
            DType::Bool(..) => Canonical::Bool(BoolArray::new(
                if BoolScalar::try_from(scalar)
                    .vortex_expect("must be bool")
                    .value()
                    .unwrap_or_default()
                {
                    BooleanBuffer::new_set(array.len())
                } else {
                    BooleanBuffer::new_unset(array.len())
                },
                validity,
            )),
            DType::Primitive(ptype, ..) => {
                match_each_native_ptype!(ptype, |P| {
                    Canonical::Primitive(PrimitiveArray::new(
                        if scalar.is_valid() {
                            Buffer::full(
                                P::try_from(scalar)
                                    .vortex_expect("Couldn't unwrap scalar to primitive"),
                                array.len(),
                            )
                        } else {
                            Buffer::zeroed(array.len())
                        },
                        validity,
                    ))
                })
            }
            DType::Decimal(decimal_type, ..) => {
                let size = smallest_storage_type(decimal_type);
                let decimal = scalar.as_decimal();
                let Some(value) = decimal.decimal_value() else {
                    let all_null = match_each_decimal_value_type!(size, |D| {
                        DecimalArray::new(Buffer::<D>::zeroed(array.len()), *decimal_type, validity)
                    });
                    return Canonical::Decimal(all_null);
                };

                let decimal_array = match_each_decimal_value!(value, |value| {
                    DecimalArray::new(Buffer::full(value, array.len()), *decimal_type, validity)
                });
                Canonical::Decimal(decimal_array)
            }
            DType::Utf8(_) => {
                let value = Utf8Scalar::try_from(scalar)
                    .vortex_expect("Must be a utf8 scalar")
                    .value();
                let const_value = value.as_ref().map(|v| v.as_bytes());
                Canonical::VarBinView(canonical_byte_view(const_value, array.dtype(), array.len()))
            }
            DType::Binary(_) => {
                let value = BinaryScalar::try_from(scalar)
                    .vortex_expect("must be a binary scalar")
                    .value();
                let const_value = value.as_ref().map(|v| v.as_slice());
                Canonical::VarBinView(canonical_byte_view(const_value, array.dtype(), array.len()))
            }
            DType::Struct(struct_dtype, _) => {
                let value = StructScalar::try_from(scalar).vortex_expect("must be struct");
                let fields: Vec<_> = match value.fields() {
                    Some(fields) => fields
                        .into_iter()
                        .map(|s| ConstantArray::new(s, array.len()).into_array())
                        .collect(),
                    None => {
                        assert!(validity.all_invalid());
                        struct_dtype
                            .fields()
                            .map(|dt| {
                                let scalar = Scalar::default_value(dt);
                                ConstantArray::new(scalar, array.len()).into_array()
                            })
                            .collect()
                    }
                };
                Canonical::Struct(StructArray::new_unchecked(
                    fields,
                    struct_dtype.clone(),
                    array.len(),
                    validity,
                ))
            }
            DType::List(..) => {
                let value = ListScalar::try_from(scalar).vortex_expect("must be list");
                Canonical::List(canonical_list_array(
                    value.elements(),
                    value.element_dtype(),
                    value.dtype().nullability(),
                    array.len(),
                ))
            }
            DType::FixedSizeList(..) => {
                unimplemented!("TODO(connor)[FixedSizeList]")
            }
            DType::Extension(ext_dtype) => {
                let s = ExtScalar::try_from(scalar).vortex_expect("must be an extension scalar");

                let storage_scalar = s.storage();
                let storage_self = ConstantArray::new(storage_scalar, array.len()).into_array();
                Canonical::Extension(ExtensionArray::new(ext_dtype.clone(), storage_self))
            }
        }
    }
}

fn canonical_byte_view(scalar_bytes: Option<&[u8]>, dtype: &DType, len: usize) -> VarBinViewArray {
    match scalar_bytes {
        None => {
            let views = buffer![BinaryView::from(0_u128); len];

            // SAFETY: for all-null the views and buffers are just zeroed, never accessed.
            unsafe {
                VarBinViewArray::new_unchecked(
                    views,
                    Default::default(),
                    dtype.clone(),
                    Validity::AllInvalid,
                )
            }
        }
        Some(scalar_bytes) => {
            // Create a view to hold the scalar bytes.
            // If the scalar cannot be inlined, allocate a single buffer large enough to hold it.
            let view = BinaryView::make_view(scalar_bytes, 0, 0);
            let mut buffers = Vec::new();
            if scalar_bytes.len() >= BinaryView::MAX_INLINED_SIZE {
                buffers.push(Buffer::copy_from(scalar_bytes));
            }

            // Clone our constant view `len` times.
            let views = buffer![view; len];

            // SAFETY: all the views are identical and point to a constant value.
            unsafe {
                VarBinViewArray::new_unchecked(
                    views,
                    Arc::from(buffers),
                    dtype.clone(),
                    Validity::from(dtype.nullability()),
                )
            }
        }
    }
}

fn canonical_list_array(
    values: Option<Vec<Scalar>>,
    element_dtype: &DType,
    list_nullability: Nullability,
    len: usize,
) -> ListArray {
    match values {
        None => unsafe {
            ListArray::new_unchecked(
                Canonical::empty(element_dtype).into_array(),
                ConstantArray::new(
                    Scalar::new(
                        DType::Primitive(PType::U64, Nullability::NonNullable),
                        ScalarValue::from(0),
                    ),
                    len + 1,
                )
                .into_array(),
                Validity::AllInvalid,
            )
        },
        Some(vs) => {
            let mut elements_builder = builder_with_capacity(element_dtype, len * vs.len());
            for _ in 0..len {
                for v in &vs {
                    elements_builder
                        .append_scalar(v)
                        .vortex_expect("must be a same dtype");
                }
            }
            let offsets = if vs.is_empty() {
                Buffer::zeroed(len + 1)
            } else {
                Buffer::from_trusted_len_iter(
                    (0..=len * vs.len()).step_by(vs.len()).map(|i| i as u64),
                )
            };

            unsafe {
                ListArray::new_unchecked(
                    elements_builder.finish(),
                    offsets.into_array(),
                    Validity::from(list_nullability),
                )
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use std::sync::Arc;

    use enum_iterator::all;
    use itertools::Itertools;
    use vortex_dtype::half::f16;
    use vortex_dtype::{DType, Nullability, PType};
    use vortex_scalar::Scalar;

    use crate::arrays::ConstantArray;
    use crate::canonical::ToCanonical;
    use crate::stats::{Stat, StatsProvider};
    use crate::{Array, IntoArray};

    #[test]
    fn test_canonicalize_null() {
        let const_null = ConstantArray::new(Scalar::null(DType::Null), 42);
        let actual = const_null.to_null();
        assert_eq!(actual.len(), 42);
        assert_eq!(actual.scalar_at(33), Scalar::null(DType::Null));
    }

    #[test]
    fn test_canonicalize_const_str() {
        let const_array = ConstantArray::new("four".to_string(), 4);

        // Check all values correct.
        let canonical = const_array.to_varbinview();

        assert_eq!(canonical.len(), 4);

        for i in 0..=3 {
            assert_eq!(canonical.scalar_at(i), "four".into());
        }
    }

    #[test]
    fn test_canonicalize_propagates_stats() {
        let scalar = Scalar::bool(true, Nullability::NonNullable);
        let const_array = ConstantArray::new(scalar, 4).into_array();
        let stats = const_array
            .statistics()
            .compute_all(&all::<Stat>().collect_vec())
            .unwrap();
        let canonical = const_array.to_canonical();
        let canonical_stats = canonical.as_ref().statistics();

        let stats_ref = stats.as_typed_ref(canonical.as_ref().dtype());

        for stat in all::<Stat>() {
            if stat.dtype(canonical.as_ref().dtype()).is_none() {
                continue;
            }
            assert_eq!(
                canonical_stats.get(stat),
                stats_ref.get(stat),
                "stat mismatch {stat}"
            );
        }
    }

    #[test]
    fn test_canonicalize_scalar_values() {
        let f16_value = f16::from_f32(5.722046e-6);
        let f16_scalar = Scalar::primitive(f16_value, Nullability::NonNullable);

        // Create a ConstantArray with the f16 scalar
        let const_array = ConstantArray::new(f16_scalar.clone(), 1).into_array();
        let canonical_const = const_array.to_primitive();

        // Verify the scalar value is preserved through canonicalization
        assert_eq!(canonical_const.scalar_at(0), f16_scalar);
    }

    #[test]
    fn test_canonicalize_lists() {
        let list_scalar = Scalar::list(
            Arc::new(DType::Primitive(PType::U64, Nullability::NonNullable)),
            vec![1u64.into(), 2u64.into()],
            Nullability::NonNullable,
        );
        let const_array = ConstantArray::new(list_scalar, 2).into_array();
        let canonical_const = const_array.to_list();
        assert_eq!(
            canonical_const.elements().to_primitive().as_slice::<u64>(),
            [1u64, 2, 1, 2]
        );
        assert_eq!(
            canonical_const.offsets().to_primitive().as_slice::<u64>(),
            [0u64, 2, 4]
        );
    }

    #[test]
    fn test_canonicalize_empty_list() {
        let list_scalar = Scalar::list(
            Arc::new(DType::Primitive(PType::U64, Nullability::NonNullable)),
            vec![],
            Nullability::NonNullable,
        );
        let const_array = ConstantArray::new(list_scalar, 2).into_array();
        let canonical_const = const_array.to_list();
        assert!(canonical_const.elements().to_primitive().is_empty());
        assert_eq!(
            canonical_const.offsets().to_primitive().as_slice::<u64>(),
            [0u64, 0, 0]
        );
    }

    #[test]
    fn test_canonicalize_null_list() {
        let list_scalar = Scalar::null(DType::List(
            Arc::new(DType::Primitive(PType::U64, Nullability::NonNullable)),
            Nullability::Nullable,
        ));
        let const_array = ConstantArray::new(list_scalar, 2).into_array();
        let canonical_const = const_array.to_list();
        assert!(canonical_const.elements().to_primitive().is_empty());
        assert_eq!(
            canonical_const.offsets().to_primitive().as_slice::<u64>(),
            [0u64, 0, 0]
        );
    }

    #[test]
    fn test_canonicalize_nullable_struct() {
        let array = ConstantArray::new(
            Scalar::null(DType::struct_(
                [(
                    "non_null_field",
                    DType::Primitive(PType::I8, Nullability::NonNullable),
                )],
                Nullability::Nullable,
            )),
            3,
        );

        let struct_array = array.to_struct();
        assert_eq!(struct_array.len(), 3);
        assert_eq!(struct_array.valid_count(), 0);

        let field = struct_array.field_by_name("non_null_field").unwrap();

        assert_eq!(
            field.dtype(),
            &DType::Primitive(PType::I8, Nullability::NonNullable)
        );
    }
}