der/
str_slice.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::{ByteSlice, DecodeValue, Decoder, EncodeValue, Encoder, Length, Result};
5use core::str;
6
7/// String slice newtype which respects the [`Length::max`] limit.
8#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord)]
9pub(crate) struct StrSlice<'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> StrSlice<'a> {
18    /// Create a new [`StrSlice`], 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 [`StrSlice`] 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 [`StrSlice`]
43    pub fn len(self) -> Length {
44        self.length
45    }
46
47    /// Is this [`StrSlice`] empty?
48    pub fn is_empty(self) -> bool {
49        self.len() == Length::ZERO
50    }
51}
52
53impl AsRef<str> for StrSlice<'_> {
54    fn as_ref(&self) -> &str {
55        self.as_str()
56    }
57}
58
59impl AsRef<[u8]> for StrSlice<'_> {
60    fn as_ref(&self) -> &[u8] {
61        self.as_bytes()
62    }
63}
64
65impl<'a> DecodeValue<'a> for StrSlice<'a> {
66    fn decode_value(decoder: &mut Decoder<'a>, length: Length) -> Result<Self> {
67        Self::from_bytes(ByteSlice::decode_value(decoder, length)?.as_bytes())
68    }
69}
70
71impl<'a> EncodeValue for StrSlice<'a> {
72    fn value_len(&self) -> Result<Length> {
73        Ok(self.length)
74    }
75
76    fn encode_value(&self, encoder: &mut Encoder<'_>) -> Result<()> {
77        encoder.bytes(self.as_ref())
78    }
79}
der/str_slice.rs

der/
str_slice.rs
