messagepack_core/decode/
nil.rs

1//! Nil and `Option` decoding helpers.
2
3use super::{Decode, DecodeBorrowed, Error};
4use crate::{formats::Format, io::IoRead};
5
6/// Decode the MessagePack `nil` value.
7pub struct NilDecoder;
8
9impl<'de> DecodeBorrowed<'de> for NilDecoder {
10    type Value = ();
11
12    fn decode_borrowed_with_format<R>(
13        format: Format,
14        _reader: &mut R,
15    ) -> core::result::Result<Self::Value, Error<R::Error>>
16    where
17        R: IoRead<'de>,
18    {
19        match format {
20            Format::Nil => Ok(()),
21            _ => Err(Error::UnexpectedFormat),
22        }
23    }
24}
25
26impl<'de> DecodeBorrowed<'de> for () {
27    type Value = ();
28
29    fn decode_borrowed_with_format<R>(
30        format: Format,
31        reader: &mut R,
32    ) -> core::result::Result<Self::Value, Error<R::Error>>
33    where
34        R: IoRead<'de>,
35    {
36        NilDecoder::decode_borrowed_with_format(format, reader)
37    }
38}
39
40impl<'de, V> Decode<'de> for Option<V>
41where
42    V: Decode<'de>,
43{
44    type Value<'a>
45        = Option<V::Value<'a>>
46    where
47        Self: 'a,
48        'de: 'a;
49    fn decode_with_format<'a, R>(
50        format: Format,
51        reader: &'a mut R,
52    ) -> Result<Self::Value<'a>, Error<R::Error>>
53    where
54        R: IoRead<'de>,
55        'de: 'a,
56    {
57        match format {
58            Format::Nil => Ok(None),
59            other => {
60                let val = V::decode_with_format(other, reader)?;
61                Ok(Some(val))
62            }
63        }
64    }
65}
66
67#[cfg(test)]
68mod tests {
69    use super::*;
70
71    #[test]
72    fn decode_nil() {
73        let buf: &[u8] = &[0xc0];
74        let mut r = crate::io::SliceReader::new(buf);
75        NilDecoder::decode(&mut r).unwrap();
76        assert_eq!(r.rest().len(), 0);
77    }
78
79    #[test]
80    fn decode_option() {
81        let buf: &[u8] = &[0xc0];
82        let mut r = crate::io::SliceReader::new(buf);
83        let decoded = Option::<bool>::decode(&mut r).unwrap();
84        assert_eq!(decoded, None);
85        assert_eq!(r.rest().len(), 0);
86
87        let buf: &[u8] = &[0xc3];
88        let mut r = crate::io::SliceReader::new(buf);
89        let decoded = Option::<bool>::decode(&mut r).unwrap();
90        assert_eq!(decoded, Some(true));
91        assert_eq!(r.rest().len(), 0);
92    }
93}
messagepack_core/decode/nil.rs

messagepack_core/decode/
nil.rs
