1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76

use alloc::fmt::{Debug, Display, Formatter, Result as FmtResult};
use core::ops::{Deref, DerefMut};
use core::str;

use crate::{BoxHeader, Header, OwnedSlice, TooLong};

/// An owned string slice.
///
/// This is the same optimisation as [`OwnedSlice`] does, but applied to `&str`.
#[derive(Clone, Default)]
pub struct Str<H: Header = BoxHeader>(OwnedSlice<u8, H>);

impl<H> Str<H>
where
    H: Header,
{
    /// Creates a new owned string slice.
    #[inline]
    pub fn new(s: &str) -> Result<Self, TooLong> {
        OwnedSlice::new(s.as_bytes()).map(Self)
    }
}

impl<H> Debug for Str<H>
where
    H: Header,
{
    #[inline]
    fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
        write!(fmt, "{:?}", self.deref())
    }
}

impl<H> Display for Str<H>
where
    H: Header,
{
    #[inline]
    fn fmt(&self, fmt: &mut Formatter) -> FmtResult {
        write!(fmt, "{}", self.deref())
    }
}

impl<H> Deref for Str<H>
where
    H: Header,
{
    type Target = str;

    #[inline]
    fn deref(&self) -> &str {
        // It was created from str originally
        unsafe { str::from_utf8_unchecked(&self.0) }
    }
}

impl DerefMut for Str<BoxHeader> {
    #[inline]
    fn deref_mut(&mut self) -> &mut Self::Target {
        // It was created from str originally
        unsafe { str::from_utf8_unchecked_mut(&mut self.0) }
    }
}

#[cfg(all(feature = "std", test))]
mod tests {
    use super::*;

    #[test]
    fn strings() {
        let s: Str = Str::new("Hello").unwrap();
        assert_eq!("Hello", s.deref());
        assert_eq!("Hello", s.to_string());
        assert_eq!("\"Hello\"", format!("{:?}", s));
    }
}