risingwave_expr_impl/scalar/
concat_ws.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 all but the first argument, with separators. The first argument is used as the
22/// separator string, and should not be NULL. Other NULL arguments are ignored.
23///
24/// # Example
25///
26/// ```slt
27/// query T
28/// select concat_ws(',', 'abcde', 2, NULL, 22);
29/// ----
30/// abcde,2,22
31///
32/// query T
33/// select concat_ws(',', variadic array['abcde', 2, NULL, 22] :: varchar[]);
34/// ----
35/// abcde,2,22
36/// ```
37#[function("concat_ws(varchar, variadic anyarray) -> varchar")]
38fn concat_ws(sep: &str, vals: impl Row, writer: &mut impl Write) {
39    let mut string_iter = vals.iter().flatten();
40    if let Some(string) = string_iter.next() {
41        string.write(writer).unwrap();
42    }
43    for string in string_iter {
44        write!(writer, "{}", sep).unwrap();
45        string.write(writer).unwrap();
46    }
47}
48
49#[cfg(test)]
50mod tests {
51    use risingwave_common::array::DataChunk;
52    use risingwave_common::row::Row;
53    use risingwave_common::test_prelude::DataChunkTestExt;
54    use risingwave_common::types::ToOwnedDatum;
55    use risingwave_common::util::iter_util::ZipEqDebug;
56    use risingwave_expr::expr::build_from_pretty;
57
58    #[tokio::test]
59    async fn test_concat_ws() {
60        let concat_ws =
61            build_from_pretty("(concat_ws:varchar $0:varchar $1:varchar $2:varchar $3:varchar)");
62        let (input, expected) = DataChunk::from_pretty(
63            "T T T T  T
64             , a b c  a,b,c
65             , . b c  b,c
66             . a b c  .
67             , . . .  (empty)
68             . . . .  .",
69        )
70        .split_column_at(4);
71
72        // test eval
73        let output = concat_ws.eval(&input).await.unwrap();
74        assert_eq!(&output, expected.column_at(0));
75
76        // test eval_row
77        for (row, expected) in input.rows().zip_eq_debug(expected.rows()) {
78            let result = concat_ws.eval_row(&row.to_owned_row()).await.unwrap();
79            assert_eq!(result, expected.datum_at(0).to_owned_datum());
80        }
81    }
82}
risingwave_expr_impl/scalar/concat_ws.rs

risingwave_expr_impl/scalar/
concat_ws.rs
