risingwave_expr_impl/scalar/
position.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 risingwave_expr::function;
16
17/// Returns the index of the first occurrence of the specified substring in the input string,
18/// or zero if the substring is not present.
19///
20/// # Example
21///
22/// ```slt
23/// query I
24/// select position('om' in 'Thomas');
25/// ----
26/// 3
27///
28/// query I
29/// select strpos('hello, world', 'lo');
30/// ----
31/// 4
32///
33/// query I
34/// select strpos('high', 'ig');
35/// ----
36/// 2
37///
38/// query I
39/// select strpos('abc', 'def');
40/// ----
41/// 0
42///
43/// query I
44/// select strpos('床前明月光', '月光');
45/// ----
46/// 4
47/// ```
48#[function("strpos(varchar, varchar) -> int4", deprecated)]
49#[function("position(varchar, varchar) -> int4")]
50pub fn position(str: &str, sub_str: &str) -> i32 {
51    match str.find(sub_str) {
52        Some(byte_idx) => (str[..byte_idx].chars().count() + 1) as i32,
53        None => 0,
54    }
55}
56
57#[cfg(test)]
58mod tests {
59
60    use super::*;
61
62    #[test]
63    fn test_length() {
64        let cases = [
65            ("hello world", "world", 7),
66            ("床前明月光", "月光", 4),
67            ("床前明月光", "故乡", 0),
68        ];
69
70        for (str, sub_str, expected) in cases {
71            assert_eq!(position(str, sub_str), expected)
72        }
73    }
74}
risingwave_expr_impl/scalar/position.rs

risingwave_expr_impl/scalar/
position.rs
