risingwave_expr_impl/scalar/
concat.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 std::fmt::Write;
16
17use risingwave_common::row::Row;
18use risingwave_common::types::ToText;
19use risingwave_expr::function;
20
21/// Concatenates the text representations of all the arguments. NULL arguments are ignored.
22///
23/// # Example
24///
25/// ```slt
26/// query T
27/// select concat('abcde', 2, NULL, 22);
28/// ----
29/// abcde222
30///
31/// query T
32/// select concat(variadic array['abcde', '2', NULL, '22']);
33/// ----
34/// abcde222
35/// ```
36#[function("concat(variadic anyarray) -> varchar")]
37fn concat(vals: impl Row, writer: &mut impl Write) {
38    for string in vals.iter().flatten() {
39        string.write(writer).unwrap();
40    }
41}
42
43#[cfg(test)]
44mod tests {
45    use risingwave_common::array::DataChunk;
46    use risingwave_common::row::Row;
47    use risingwave_common::test_prelude::DataChunkTestExt;
48    use risingwave_common::types::ToOwnedDatum;
49    use risingwave_common::util::iter_util::ZipEqDebug;
50    use risingwave_expr::expr::build_from_pretty;
51
52    #[tokio::test]
53    async fn test_concat() {
54        let concat = build_from_pretty("(concat:varchar $0:varchar $1:varchar $2:varchar)");
55        let (input, expected) = DataChunk::from_pretty(
56            "T T T  T
57             a b c  abc
58             . b c  bc
59             . . .  (empty)",
60        )
61        .split_column_at(3);
62
63        // test eval
64        let output = concat.eval(&input).await.unwrap();
65        assert_eq!(&output, expected.column_at(0));
66
67        // test eval_row
68        for (row, expected) in input.rows().zip_eq_debug(expected.rows()) {
69            let result = concat.eval_row(&row.to_owned_row()).await.unwrap();
70            assert_eq!(result, expected.datum_at(0).to_owned_datum());
71        }
72    }
73}
risingwave_expr_impl/scalar/concat.rs

risingwave_expr_impl/scalar/
concat.rs
