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 [`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/// ```
23///
24/// [`Value`]: enum.Value.html
25pub struct Deserialize<'de, T: Type + serde::Deserialize<'de>>(
26    pub T,
27    std::marker::PhantomData<&'de T>,
28);
29
30impl<'de, T: Type + serde::Deserialize<'de>> serde::Deserialize<'de> for Deserialize<'de, T> {
31    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
32    where
33        D: Deserializer<'de>,
34    {
35        const FIELDS: &[&str] = &["signature", "value"];
36        Ok(Deserialize(
37            deserializer.deserialize_struct(
38                "Variant",
39                FIELDS,
40                DeserializeValueVisitor(PhantomData),
41            )?,
42            PhantomData,
43        ))
44    }
45}
46
47struct DeserializeValueVisitor<T>(PhantomData<T>);
48
49impl<'de, T: Type + serde::Deserialize<'de>> Visitor<'de> for DeserializeValueVisitor<T> {
50    type Value = T;
51
52    fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
53        formatter.write_str("Variant")
54    }
55
56    fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
57    where
58        V: SeqAccess<'de>,
59    {
60        let sig: Signature = seq
61            .next_element()?
62            .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?;
63        if T::SIGNATURE != &sig {
64            return Err(serde::de::Error::invalid_value(
65                serde::de::Unexpected::Str(&sig.to_string()),
66                &"the value signature",
67            ));
68        }
69
70        seq.next_element()?
71            .ok_or_else(|| serde::de::Error::invalid_length(1, &self))
72    }
73}
74
75impl<'de, T: Type + serde::Deserialize<'de>> Type for Deserialize<'de, T> {
76    const SIGNATURE: &'static Signature = &Signature::Variant;
77}
78
79/// Deserialize a value as a [`enum@zvariant::Value`].
80pub fn deserialize<'de, T, D>(deserializer: D) -> std::result::Result<T, D::Error>
81where
82    D: Deserializer<'de>,
83    T: serde::Deserialize<'de> + Type + 'de,
84{
85    use serde::Deserialize as _;
86
87    Deserialize::deserialize(deserializer).map(|v| v.0)
88}
89
90/// Deserialize an optional value as a [`enum@zvariant::Value`].
91pub fn deserialize_optional<'de, T, D>(deserializer: D) -> std::result::Result<Option<T>, D::Error>
92where
93    D: Deserializer<'de>,
94    T: serde::Deserialize<'de> + Type + 'de,
95{
96    deserialize(deserializer).map(Some)
97}
zvariant/as_value/deserialize.rs

zvariant/as_value/
deserialize.rs
