risingwave_expr_impl/scalar/
translate.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::collections::HashMap;
16use std::fmt::Write;
17
18use risingwave_expr::function;
19
20#[function("translate(varchar, varchar, varchar) -> varchar")]
21pub fn translate(s: &str, match_str: &str, replace_str: &str, writer: &mut impl Write) {
22    let mut char_map = HashMap::new();
23    let mut match_chars = match_str.chars();
24    let mut replace_chars = replace_str.chars();
25
26    loop {
27        let m = match_chars.next();
28        let r = replace_chars.next();
29        if let Some(match_c) = m {
30            char_map.entry(match_c).or_insert(r);
31        } else {
32            break;
33        }
34    }
35
36    let iter = s.chars().filter_map(|c| match char_map.get(&c) {
37        Some(Some(m)) => Some(*m),
38        Some(None) => None,
39        None => Some(c),
40    });
41    for c in iter {
42        writer.write_char(c).unwrap();
43    }
44}
45
46#[cfg(test)]
47mod tests {
48    use super::*;
49
50    #[test]
51    fn test_translate() {
52        let cases = [
53            ("hello world", "lo", "12", "he112 w2r1d"),
54            (
55                "人之初，性本善。性相近，习相远。",
56                "人性。",
57                "abcd",
58                "a之初，b本善cb相近，习相远c",
59            ),
60            (
61                "奇点无限 RisingWave Labs",
62                "Labs ",
63                "1234",
64                "奇点无限Ri4ingW2ve1234",
65            ),
66        ];
67
68        for (s, match_str, replace_str, expected) in cases {
69            let mut writer = String::new();
70            translate(s, match_str, replace_str, &mut writer);
71            assert_eq!(writer, expected);
72        }
73    }
74}
risingwave_expr_impl/scalar/translate.rs

risingwave_expr_impl/scalar/
translate.rs
