zvariant/as_value/
deserialize.rs

1use core::str;
2use std::marker::PhantomData;
3
4use serde::de::{Deserializer, SeqAccess, Visitor};
5
6use crate::{Signature, Type};
7
8/// A wrapper to deserialize a value to `T: Type + serde::Deserialize`.
9///
10/// When the type of a value is well-known, you may avoid the cost and complexity of wrapping to a
11/// generic [`enum@crate::Value`] and instead use this wrapper.
12///
13/// ```
14/// # use zvariant::{to_bytes, serialized::Context, as_value::{Deserialize, Serialize}, LE};
15/// #
16/// # let ctxt = Context::new_dbus(LE, 0);
17/// # let array = [0, 1, 2];
18/// # let v = Serialize(&array);
19/// # let encoded = to_bytes(ctxt, &v).unwrap();
20/// let decoded: Deserialize<[u8; 3]> = encoded.deserialize().unwrap().0;
21/// # assert_eq!(decoded.0, array);
22/// ```
23pub struct Deserialize<'de, T: Type + serde::Deserialize<'de>>(
24    pub T,
25    std::marker::PhantomData<&'de T>,
26);
27
28impl<'de, T: Type + serde::Deserialize<'de>> serde::Deserialize<'de> for Deserialize<'de, T> {
29    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
30    where
31        D: Deserializer<'de>,
32    {
33        // `Value`/`OwnedValue` (and any other type whose signature is already `v`) deserialize
34        // themselves from a variant, so the extra unwrapping below would expect a
35        // variant-of-variant. Just delegate to their own `Deserialize` impl in that case.
36        if T::SIGNATURE == &Signature::Variant {
37            return Ok(Deserialize(T::deserialize(deserializer)?, PhantomData));
38        }
39
40        const FIELDS: &[&str] = &["signature", "value"];
41        Ok(Deserialize(
42            deserializer.deserialize_struct(
43                "Variant",
44                FIELDS,
45                DeserializeValueVisitor(PhantomData),
46            )?,
47            PhantomData,
48        ))
49    }
50}
51
52struct DeserializeValueVisitor<T>(PhantomData<T>);
53
54impl<'de, T: Type + serde::Deserialize<'de>> Visitor<'de> for DeserializeValueVisitor<T> {
55    type Value = T;
56
57    fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
58        formatter.write_str("Variant")
59    }
60
61    fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
62    where
63        V: SeqAccess<'de>,
64    {
65        let sig: Signature = seq
66            .next_element()?
67            .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?;
68        if T::SIGNATURE != &sig {
69            return Err(serde::de::Error::invalid_value(
70                serde::de::Unexpected::Str(&sig.to_string()),
71                &"the value signature",
72            ));
73        }
74
75        seq.next_element()?
76            .ok_or_else(|| serde::de::Error::invalid_length(1, &self))
77    }
78}
79
80impl<'de, T: Type + serde::Deserialize<'de>> Type for Deserialize<'de, T> {
81    const SIGNATURE: &'static Signature = &Signature::Variant;
82}
83
84/// Deserialize a value as a [`enum@zvariant::Value`].
85pub fn deserialize<'de, T, D>(deserializer: D) -> std::result::Result<T, D::Error>
86where
87    D: Deserializer<'de>,
88    T: serde::Deserialize<'de> + Type + 'de,
89{
90    use serde::Deserialize as _;
91
92    Deserialize::deserialize(deserializer).map(|v| v.0)
93}
94
95/// Deserialize an optional value as a [`enum@zvariant::Value`].
96pub fn deserialize_optional<'de, T, D>(deserializer: D) -> std::result::Result<Option<T>, D::Error>
97where
98    D: Deserializer<'de>,
99    T: serde::Deserialize<'de> + Type + 'de,
100{
101    deserialize(deserializer).map(Some)
102}
zvariant/as_value/deserialize.rs

zvariant/as_value/
deserialize.rs
