risingwave_expr/expr/
value.rs

1// Copyright 2025 RisingWave Labs
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use either::Either;
16use risingwave_common::array::*;
17use risingwave_common::for_all_variants;
18use risingwave_common::types::{Datum, DatumRef, Scalar, ToDatumRef};
19
20/// The type-erased return value of an expression.
21///
22/// It can be either an array, or a scalar if all values in the array are the same.
23#[derive(Debug, Clone)]
24pub enum ValueImpl {
25    Array(ArrayRef),
26    Scalar { value: Datum, capacity: usize },
27}
28
29impl From<ArrayRef> for ValueImpl {
30    fn from(value: ArrayRef) -> Self {
31        Self::Array(value)
32    }
33}
34
35impl ValueImpl {
36    /// Number of scalars in this value.
37    #[inline]
38    #[expect(clippy::len_without_is_empty)]
39    pub fn len(&self) -> usize {
40        self.iter().len()
41    }
42
43    /// Iterates over all scalars in this value.
44    pub fn iter(&self) -> impl ExactSizeIterator<Item = DatumRef<'_>> + '_ {
45        match self {
46            Self::Array(array) => Either::Left(array.iter()),
47            Self::Scalar { value, capacity } => {
48                Either::Right(itertools::repeat_n(value.to_datum_ref(), *capacity))
49            }
50        }
51    }
52}
53
54/// The generic reference type of [`ValueImpl`]. Used as the arguments of expressions.
55#[derive(Debug, Clone, Copy)]
56pub enum ValueRef<'a, A: Array> {
57    Array(&'a A),
58    Scalar {
59        value: Option<<A as Array>::RefItem<'a>>,
60        capacity: usize,
61    },
62}
63
64impl<'a, A: Array> ValueRef<'a, A> {
65    /// Number of scalars in this value.
66    #[inline]
67    #[expect(clippy::len_without_is_empty)]
68    pub fn len(self) -> usize {
69        self.iter().len()
70    }
71
72    /// Iterates over all scalars in this value.
73    pub fn iter(self) -> impl ExactSizeIterator<Item = Option<A::RefItem<'a>>> + 'a {
74        match self {
75            Self::Array(array) => Either::Left(array.iter()),
76            Self::Scalar { value, capacity } => Either::Right(itertools::repeat_n(value, capacity)),
77        }
78    }
79}
80
81macro_rules! impl_convert {
82    ($( { $data_type:ident, $variant_name:ident, $suffix_name:ident, $scalar:ty, $scalar_ref:ty, $array:ty, $builder:ty } ),*) => {
83        $(
84            paste::paste! {
85                /// Converts a type-erased value to a reference of a specific array type.
86                impl<'a> From<&'a ValueImpl> for ValueRef<'a, $array> {
87                    fn from(value: &'a ValueImpl) -> Self {
88                        match value {
89                            ValueImpl::Array(array) => {
90                                let array = array.[<as_ $suffix_name>]();
91                                ValueRef::Array(array)
92                            },
93                            ValueImpl::Scalar { value, capacity } => {
94                                let value = value.as_ref().map(|v| v.[<as_ $suffix_name>]().as_scalar_ref());
95                                ValueRef::Scalar { value, capacity: *capacity }
96                            },
97                        }
98                    }
99                }
100            }
101        )*
102    };
103}
104
105for_all_variants! { impl_convert }
risingwave_expr/expr/value.rs

risingwave_expr/expr/
value.rs
