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

zvariant/as_value/
deserialize.rs
