cu_bincode/de/
decoder.rs

1use super::{
2    read::{BorrowReader, Reader},
3    BorrowDecoder, Decoder,
4};
5use crate::{config::Config, error::DecodeError, utils::Sealed};
6
7/// A Decoder that reads bytes from a given reader `R`.
8///
9/// This struct should rarely be used.
10/// In most cases, prefer any of the `decode` functions.
11///
12/// The ByteOrder that is chosen will impact the endianness that
13/// is used to read integers out of the reader.
14///
15/// ```
16/// # extern crate cu_bincode as bincode;
17/// # let slice: &[u8] = &[0, 0, 0, 0];
18/// # let some_reader = bincode::de::read::SliceReader::new(slice);
19/// use bincode::de::{DecoderImpl, Decode};
20/// let mut context = ();
21/// let mut decoder = DecoderImpl::new(some_reader, bincode::config::standard(), &mut context);
22/// // this u32 can be any Decode
23/// let value = u32::decode(&mut decoder).unwrap();
24/// ```
25pub struct DecoderImpl<R, C: Config, Context> {
26    reader: R,
27    config: C,
28    bytes_read: usize,
29    context: Context,
30}
31
32impl<R: Reader, C: Config, Context> DecoderImpl<R, C, Context> {
33    /// Construct a new Decoder
34    pub fn new(reader: R, config: C, context: Context) -> DecoderImpl<R, C, Context> {
35        DecoderImpl {
36            reader,
37            config,
38            bytes_read: 0,
39            context,
40        }
41    }
42}
43
44impl<R, C: Config, Context> Sealed for DecoderImpl<R, C, Context> {}
45
46impl<'de, R: BorrowReader<'de>, C: Config, Context> BorrowDecoder<'de>
47    for DecoderImpl<R, C, Context>
48{
49    type BR = R;
50
51    fn borrow_reader(&mut self) -> &mut Self::BR {
52        &mut self.reader
53    }
54}
55
56impl<R: Reader, C: Config, Context> Decoder for DecoderImpl<R, C, Context> {
57    type R = R;
58
59    type C = C;
60    type Context = Context;
61
62    fn reader(&mut self) -> &mut Self::R {
63        &mut self.reader
64    }
65
66    fn config(&self) -> &Self::C {
67        &self.config
68    }
69
70    #[inline]
71    fn claim_bytes_read(&mut self, n: usize) -> Result<(), DecodeError> {
72        // C::LIMIT is a const so this check should get compiled away
73        if let Some(limit) = C::LIMIT {
74            // Make sure we don't accidentally overflow `bytes_read`
75            self.bytes_read = self
76                .bytes_read
77                .checked_add(n)
78                .ok_or(DecodeError::LimitExceeded)?;
79            if self.bytes_read > limit {
80                Err(DecodeError::LimitExceeded)
81            } else {
82                Ok(())
83            }
84        } else {
85            Ok(())
86        }
87    }
88
89    #[inline]
90    fn unclaim_bytes_read(&mut self, n: usize) {
91        // C::LIMIT is a const so this check should get compiled away
92        if C::LIMIT.is_some() {
93            // We should always be claiming more than we unclaim, so this should never underflow
94            self.bytes_read -= n;
95        }
96    }
97
98    fn context(&mut self) -> &mut Self::Context {
99        &mut self.context
100    }
101}
102
103pub struct WithContext<'a, D: ?Sized, C> {
104    pub(crate) decoder: &'a mut D,
105    pub(crate) context: C,
106}
107
108impl<C, D: Decoder + ?Sized> Sealed for WithContext<'_, D, C> {}
109
110impl<Context, D: Decoder + ?Sized> Decoder for WithContext<'_, D, Context> {
111    type R = D::R;
112
113    type C = D::C;
114
115    type Context = Context;
116
117    fn context(&mut self) -> &mut Self::Context {
118        &mut self.context
119    }
120
121    fn reader(&mut self) -> &mut Self::R {
122        self.decoder.reader()
123    }
124
125    fn config(&self) -> &Self::C {
126        self.decoder.config()
127    }
128
129    fn claim_bytes_read(&mut self, n: usize) -> Result<(), DecodeError> {
130        self.decoder.claim_bytes_read(n)
131    }
132
133    fn unclaim_bytes_read(&mut self, n: usize) {
134        self.decoder.unclaim_bytes_read(n)
135    }
136}
137
138impl<'de, C, D: BorrowDecoder<'de>> BorrowDecoder<'de> for WithContext<'_, D, C> {
139    type BR = D::BR;
140    fn borrow_reader(&mut self) -> &mut Self::BR {
141        self.decoder.borrow_reader()
142    }
143}
cu_bincode/de/decoder.rs

cu_bincode/de/
decoder.rs
