der/
str_ref.rs

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1//! Common handling for types backed by `str` slices with enforcement of a
2//! library-level length limitation i.e. `Length::max()`.
3
4use crate::{BytesRef, DecodeValue, EncodeValue, Header, Length, Reader, Result, Writer};
5use core::str;
6
7/// String slice newtype which respects the [`Length::max`] limit.
8#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
9pub struct StrRef<'a> {
10    /// Inner value
11    pub(crate) inner: &'a str,
12
13    /// Precomputed `Length` (avoids possible panicking conversions)
14    pub(crate) length: Length,
15}
16
17impl<'a> StrRef<'a> {
18    /// Create a new [`StrRef`], ensuring that the byte representation of
19    /// the provided `str` value is shorter than `Length::max()`.
20    pub fn new(s: &'a str) -> Result<Self> {
21        Ok(Self {
22            inner: s,
23            length: Length::try_from(s.as_bytes().len())?,
24        })
25    }
26
27    /// Parse a [`StrRef`] from UTF-8 encoded bytes.
28    pub fn from_bytes(bytes: &'a [u8]) -> Result<Self> {
29        Self::new(str::from_utf8(bytes)?)
30    }
31
32    /// Borrow the inner `str`
33    pub fn as_str(&self) -> &'a str {
34        self.inner
35    }
36
37    /// Borrow the inner byte slice
38    pub fn as_bytes(&self) -> &'a [u8] {
39        self.inner.as_bytes()
40    }
41
42    /// Get the [`Length`] of this [`StrRef`]
43    pub fn len(self) -> Length {
44        self.length
45    }
46
47    /// Is this [`StrRef`] empty?
48    pub fn is_empty(self) -> bool {
49        self.len() == Length::ZERO
50    }
51}
52
53impl AsRef<str> for StrRef<'_> {
54    fn as_ref(&self) -> &str {
55        self.as_str()
56    }
57}
58
59impl AsRef<[u8]> for StrRef<'_> {
60    fn as_ref(&self) -> &[u8] {
61        self.as_bytes()
62    }
63}
64
65impl<'a> DecodeValue<'a> for StrRef<'a> {
66    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
67        Self::from_bytes(BytesRef::decode_value(reader, header)?.as_slice())
68    }
69}
70
71impl<'a> EncodeValue for StrRef<'a> {
72    fn value_len(&self) -> Result<Length> {
73        Ok(self.length)
74    }
75
76    fn encode_value(&self, writer: &mut impl Writer) -> Result<()> {
77        writer.write(self.as_ref())
78    }
79}
80
81#[cfg(feature = "alloc")]
82mod allocating {
83    use super::StrRef;
84    use crate::{referenced::RefToOwned, StrOwned};
85
86    impl<'a> RefToOwned<'a> for StrRef<'a> {
87        type Owned = StrOwned;
88        fn ref_to_owned(&self) -> Self::Owned {
89            StrOwned::from(*self)
90        }
91    }
92}
der/str_ref.rs

der/
str_ref.rs
