vec_strings/
two_strs.rs

1use core::fmt;
2use core::str;
3
4/// Box of two strings.
5/// Store two strings efficiently in an immutable way.
6#[derive(Debug, Eq, PartialEq, Clone, Hash)]
7pub struct TwoStrs(Box<[u8]>);
8
9impl From<(&str, &str)> for TwoStrs {
10    fn from((s1, s2): (&str, &str)) -> Self {
11        Self::new(s1, s2)
12    }
13}
14
15impl TwoStrs {
16    /// * `s1` - must not contain null byte.
17    /// * `s2` - must not contain null byte.
18    pub fn new(s1: &str, s2: &str) -> Self {
19        let iter1 = s1.as_bytes().iter().copied().filter(|byte| *byte != b'\0');
20        let iter2 = s2.as_bytes().iter().copied().filter(|byte| *byte != b'\0');
21
22        let len1 = iter1.clone().count();
23        let len2 = iter2.clone().count();
24
25        let mut bytes = Vec::with_capacity(len1 + 1 + len2);
26
27        if len1 == s1.len() {
28            bytes.extend_from_slice(s1.as_bytes());
29        } else {
30            bytes.extend(iter1);
31        }
32
33        bytes.push(0);
34
35        if len2 == s2.len() {
36            bytes.extend_from_slice(s2.as_bytes());
37        } else {
38            bytes.extend(iter2);
39        }
40
41        Self(bytes.into_boxed_slice())
42    }
43
44    pub fn get(&self) -> (&str, &str) {
45        let pos = self.0.iter().position(|byte| *byte == 0).unwrap();
46
47        (
48            unsafe { str::from_utf8_unchecked(&self.0[..pos]) },
49            unsafe { str::from_utf8_unchecked(&self.0[pos + 1..]) },
50        )
51    }
52}
53
54impl fmt::Display for TwoStrs {
55    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> Result<(), fmt::Error> {
56        let (s1, s2) = self.get();
57        write!(f, "({}, {})", s1, s2)
58    }
59}
60
61#[cfg(test)]
62mod tests {
63    use super::TwoStrs;
64
65    fn assert(s1: &str, s2: &str) {
66        let two_strs = TwoStrs::new(s1, s2);
67        assert_eq!(two_strs.get(), (s1, s2));
68    }
69
70    #[test]
71    fn test() {
72        assert("", "");
73        assert("12", "");
74        assert("", "12");
75        assert("12", "12");
76        assert("12", "2333");
77        assert("acdbd3", "2333");
78    }
79
80    #[allow(clippy::octal_escapes)]
81    #[test]
82    fn test_null() {
83        let two_strs = TwoStrs::new("1\023d\0", "\023e\0");
84        assert_eq!(two_strs.get(), ("123d", "23e"));
85    }
86}
vec_strings/two_strs.rs

vec_strings/
two_strs.rs
