risingwave_expr_impl/scalar/
trim.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_expr::function;
18
19#[function("trim(varchar) -> varchar")]
20pub fn trim(s: &str, writer: &mut impl Write) {
21    writer.write_str(s.trim()).unwrap();
22}
23
24/// Note: the behavior of `ltrim` in `PostgreSQL` and `trim_start` (or `trim_left`) in Rust
25/// are actually different when the string is in right-to-left languages like Arabic or Hebrew.
26/// Since we would like to simplify the implementation, currently we omit this case.
27#[function("ltrim(varchar) -> varchar")]
28pub fn ltrim(s: &str, writer: &mut impl Write) {
29    writer.write_str(s.trim_start()).unwrap();
30}
31
32/// Note: the behavior of `rtrim` in `PostgreSQL` and `trim_end` (or `trim_right`) in Rust
33/// are actually different when the string is in right-to-left languages like Arabic or Hebrew.
34/// Since we would like to simplify the implementation, currently we omit this case.
35#[function("rtrim(varchar) -> varchar")]
36pub fn rtrim(s: &str, writer: &mut impl Write) {
37    writer.write_str(s.trim_end()).unwrap();
38}
39
40#[function("trim(varchar, varchar) -> varchar")]
41pub fn trim_characters(s: &str, characters: &str, writer: &mut impl Write) {
42    let pattern = |c| characters.chars().any(|ch| ch == c);
43    // We remark that feeding a &str and a slice of chars into trim_left/right_matches
44    // means different, one is matching with the entire string and the other one is matching
45    // with any char in the slice.
46    writer.write_str(s.trim_matches(pattern)).unwrap();
47}
48
49#[function("ltrim(varchar, varchar) -> varchar")]
50pub fn ltrim_characters(s: &str, characters: &str, writer: &mut impl Write) {
51    let pattern = |c| characters.chars().any(|ch| ch == c);
52    writer.write_str(s.trim_start_matches(pattern)).unwrap();
53}
54
55#[function("rtrim(varchar, varchar) -> varchar")]
56pub fn rtrim_characters(s: &str, characters: &str, writer: &mut impl Write) {
57    let pattern = |c| characters.chars().any(|ch| ch == c);
58    writer.write_str(s.trim_end_matches(pattern)).unwrap();
59}
60
61#[cfg(test)]
62mod tests {
63    use super::*;
64
65    #[test]
66    fn test_trim() {
67        let cases = [
68            (" Hello\tworld\t", "Hello\tworld"),
69            (" 空I ❤️ databases空 ", "空I ❤️ databases空"),
70        ];
71
72        for (s, expected) in cases {
73            let mut writer = String::new();
74            trim(s, &mut writer);
75            assert_eq!(writer, expected);
76        }
77    }
78
79    #[test]
80    fn test_ltrim() {
81        let cases = [
82            (" \tHello\tworld\t", "Hello\tworld\t"),
83            (" \t空I ❤️ databases空 ", "空I ❤️ databases空 "),
84        ];
85
86        for (s, expected) in cases {
87            let mut writer = String::new();
88            ltrim(s, &mut writer);
89            assert_eq!(writer, expected);
90        }
91    }
92
93    #[test]
94    fn test_rtrim() {
95        let cases = [
96            (" \tHello\tworld\t ", " \tHello\tworld"),
97            (" \t空I ❤️ databases空\t ", " \t空I ❤️ databases空"),
98        ];
99
100        for (s, expected) in cases {
101            let mut writer = String::new();
102            rtrim(s, &mut writer);
103            assert_eq!(writer, expected);
104        }
105    }
106
107    #[test]
108    fn test_trim_characters() {
109        let cases = [
110            ("Hello world", "Hdl", "ello wor"),
111            ("abcde", "aae", "bcd"),
112            ("zxy", "yxz", ""),
113        ];
114
115        for (s, characters, expected) in cases {
116            let mut writer = String::new();
117            trim_characters(s, characters, &mut writer);
118            assert_eq!(writer, expected);
119        }
120    }
121
122    #[test]
123    fn test_ltrim_characters() {
124        let cases = [
125            ("Hello world", "Hdl", "ello world"),
126            ("abcde", "aae", "bcde"),
127            ("zxy", "yxz", ""),
128        ];
129
130        for (s, characters, expected) in cases {
131            let mut writer = String::new();
132            ltrim_characters(s, characters, &mut writer);
133            assert_eq!(writer, expected);
134        }
135    }
136
137    #[test]
138    fn test_rtrim_characters() {
139        let cases = [
140            ("Hello world", "Hdl", "Hello wor"),
141            ("abcde", "aae", "abcd"),
142            ("zxy", "yxz", ""),
143        ];
144
145        for (s, characters, expected) in cases {
146            let mut writer = String::new();
147            rtrim_characters(s, characters, &mut writer);
148            assert_eq!(writer, expected);
149        }
150    }
151}
risingwave_expr_impl/scalar/trim.rs

risingwave_expr_impl/scalar/
trim.rs
