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 name:"zvariant::Value",
42 FIELDS,
43 visitor: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}
83