zvariant/
deserialize_value.rs

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1use core::str;
2use std::marker::PhantomData;
3
4use serde::de::{Deserialize, Deserializer, SeqAccess, Visitor};
5use static_assertions::assert_impl_all;
6
7use crate::{Signature, Type, Value};
8
9/// A wrapper to deserialize a value to `T: Type + Deserialize`.
10///
11/// When the type of a value is well-known, you may avoid the cost and complexity of wrapping to a
12/// generic [`Value`] and instead use this wrapper.
13///
14/// ```
15/// # use zvariant::{to_bytes, serialized::Context, DeserializeValue, SerializeValue, LE};
16/// #
17/// # let ctxt = Context::new_dbus(LE, 0);
18/// # let array = [0, 1, 2];
19/// # let v = SerializeValue(&array);
20/// # let encoded = to_bytes(ctxt, &v).unwrap();
21/// let decoded: DeserializeValue<[u8; 3]> = encoded.deserialize().unwrap().0;
22/// # assert_eq!(decoded.0, array);
23/// ```
24///
25/// [`Value`]: enum.Value.html
26pub struct DeserializeValue<'de, T: Type + Deserialize<'de>>(
27    pub T,
28    std::marker::PhantomData<&'de T>,
29);
30
31assert_impl_all!(DeserializeValue<'_, i32>: Send, Sync, Unpin);
32
33impl<'de, T: Type + Deserialize<'de>> Deserialize<'de> for DeserializeValue<'de, T> {
34    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
35    where
36        D: Deserializer<'de>,
37    {
38        const FIELDS: &[&str] = &["zvariant::Value::Signature", "zvariant::Value::Value"];
39        Ok(DeserializeValue(
40            deserializer.deserialize_struct(
41                "zvariant::Value",
42                FIELDS,
43                DeserializeValueVisitor(PhantomData),
44            )?,
45            PhantomData,
46        ))
47    }
48}
49
50struct DeserializeValueVisitor<T>(PhantomData<T>);
51
52impl<'de, T: Type + Deserialize<'de>> Visitor<'de> for DeserializeValueVisitor<T> {
53    type Value = T;
54
55    fn expecting(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
56        formatter.write_str("zvariant::Value")
57    }
58
59    fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
60    where
61        V: SeqAccess<'de>,
62    {
63        let sig: Signature<'_> = seq
64            .next_element()?
65            .ok_or_else(|| serde::de::Error::invalid_length(0, &self))?;
66        if sig != T::signature() {
67            return Err(serde::de::Error::invalid_value(
68                serde::de::Unexpected::Str(&sig),
69                &"the value signature",
70            ));
71        }
72
73        seq.next_element()?
74            .ok_or_else(|| serde::de::Error::invalid_length(1, &self))
75    }
76}
77
78impl<'de, T: Type + Deserialize<'de>> Type for DeserializeValue<'de, T> {
79    fn signature() -> Signature<'static> {
80        Value::signature()
81    }
82}
zvariant/deserialize_value.rs

zvariant/
deserialize_value.rs
