1use crate::{FixedTag, Header, Reader, Result, SliceReader};
4use core::marker::PhantomData;
5
6#[cfg(feature = "pem")]
7use crate::{pem::PemLabel, PemReader};
8
9#[cfg(doc)]
10use crate::{Length, Tag};
11
12#[cfg(feature = "alloc")]
13use alloc::boxed::Box;
14
15pub trait Decode<'a>: Sized {
20 fn decode<R: Reader<'a>>(decoder: &mut R) -> Result<Self>;
22
23 fn from_der(bytes: &'a [u8]) -> Result<Self> {
25 let mut reader = SliceReader::new(bytes)?;
26 let result = Self::decode(&mut reader)?;
27 reader.finish(result)
28 }
29}
30
31impl<'a, T> Decode<'a> for T
32where
33 T: DecodeValue<'a> + FixedTag,
34{
35 fn decode<R: Reader<'a>>(reader: &mut R) -> Result<T> {
36 let header = Header::decode(reader)?;
37 header.tag.assert_eq(T::TAG)?;
38 T::decode_value(reader, header)
39 }
40}
41
42impl<'a, T> Decode<'a> for PhantomData<T>
45where
46 T: ?Sized,
47{
48 fn decode<R: Reader<'a>>(_reader: &mut R) -> Result<PhantomData<T>> {
49 Ok(PhantomData)
50 }
51}
52
53pub trait DecodeOwned: for<'a> Decode<'a> {}
62
63impl<T> DecodeOwned for T where T: for<'a> Decode<'a> {}
64
65#[cfg(feature = "pem")]
70pub trait DecodePem: DecodeOwned + PemLabel {
71 fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self>;
73}
74
75#[cfg(feature = "pem")]
76impl<T: DecodeOwned + PemLabel> DecodePem for T {
77 fn from_pem(pem: impl AsRef<[u8]>) -> Result<Self> {
78 let mut reader = PemReader::new(pem.as_ref())?;
79 Self::validate_pem_label(reader.type_label())?;
80 T::decode(&mut reader)
81 }
82}
83
84pub trait DecodeValue<'a>: Sized {
87 fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self>;
89}
90
91#[cfg(feature = "alloc")]
92impl<'a, T> DecodeValue<'a> for Box<T>
93where
94 T: DecodeValue<'a>,
95{
96 fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> Result<Self> {
97 Ok(Box::new(T::decode_value(reader, header)?))
98 }
99}