risingwave_common/row/
repeat_n.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 super::Row;
16use crate::types::{DatumRef, ToDatumRef};
17
18/// Row for the [`repeat_n`] function.
19#[derive(Debug, Clone, Copy)]
20pub struct RepeatN<D> {
21    datum: D,
22    n: usize,
23}
24
25impl<D: PartialEq> PartialEq for RepeatN<D> {
26    fn eq(&self, other: &Self) -> bool {
27        if self.n == 0 && other.n == 0 {
28            true
29        } else {
30            self.datum == other.datum && self.n == other.n
31        }
32    }
33}
34impl<D: Eq> Eq for RepeatN<D> {}
35
36impl<D: ToDatumRef> Row for RepeatN<D> {
37    #[inline]
38    fn datum_at(&self, index: usize) -> crate::types::DatumRef<'_> {
39        if index < self.n {
40            self.datum.to_datum_ref()
41        } else {
42            panic!(
43                "index out of bounds: the len is {} but the index is {}",
44                self.n, index
45            )
46        }
47    }
48
49    #[inline]
50    unsafe fn datum_at_unchecked(&self, _index: usize) -> crate::types::DatumRef<'_> {
51        // Always ignore the index and return the datum, which is okay for undefined behavior.
52        self.datum.to_datum_ref()
53    }
54
55    #[inline]
56    fn len(&self) -> usize {
57        self.n
58    }
59
60    #[inline]
61    fn iter(&self) -> impl Iterator<Item = DatumRef<'_>> {
62        std::iter::repeat_n(self.datum.to_datum_ref(), self.n)
63    }
64}
65
66/// Create a row which contains `n` repetitions of `datum`.
67pub fn repeat_n<D: ToDatumRef>(datum: D, n: usize) -> RepeatN<D> {
68    RepeatN { datum, n }
69}
risingwave_common/row/repeat_n.rs

risingwave_common/row/
repeat_n.rs
