Trait DeserializeEnum

Source

pub trait DeserializeEnum<'borr, NE>: InterfaceType {
    type Proxy;

    // Required method
    fn deserialize_enum(s: Self::Proxy) -> Result<NE, RBoxError>;
}

Expand description

Describes how a nonexhaustive enum is deserialized.

Generally this delegates to a library function, so that the implementation can be delegated to the implementation crate.

This is generally implemented by the interface of an enum (Enum_Interface for Enum),which also implements InterfaceType).

The NE type parameter is expected to be NonExhaustive.

§Example

use abi_stable::{
    nonexhaustive_enum::{DeserializeEnum, NonExhaustive, NonExhaustiveFor},
    external_types::RawValueRef,
    std_types::{RBoxError, RResult, ROk, RErr, RStr, RString},
    rstr, StableAbi,
};

let input = r#"{"C": {"name": "hello"}}"#;
let ne = serde_json::from_str::<NonExhaustiveFor<Foo>>(input).unwrap();
assert_eq!(ne, Foo::C{name: "hello".into()});


#[repr(u8)]
#[derive(StableAbi, Debug, PartialEq, Eq, serde::Deserialize)]
#[sabi(kind(WithNonExhaustive(
    size = 64,
    traits(Debug, PartialEq, Eq, Deserialize)
)))]
pub enum Foo {
    A,
    B(i8),
    C {
        name: RString
    },
}

impl<'borr> DeserializeEnum<'borr, NonExhaustiveFor<Foo>> for Foo_Interface {
    /// The intermediate type the `NE` is converted from,to deserialize it.
    type Proxy = RawValueRef<'borr>;

    /// Deserializes an enum from its proxy type.
    fn deserialize_enum(s: Self::Proxy) -> Result<NonExhaustiveFor<Foo>, RBoxError> {
        deserialize_foo(s.get_rstr()).into_result()
    }
}

/////////////
// everything below could be defined in an implementation crate
//
// This allows the library that defines the enum to add variants,
// and deserialize the variants that it added,
// regardless of whether the dependent crates know about those variants.

extern "C" fn deserialize_foo(s: RStr<'_>) -> RResult<NonExhaustiveFor<Foo>, RBoxError> {
    abi_stable::extern_fn_panic_handling!{
        match serde_json::from_str::<Foo>(s.into()) {
            Ok(x) => ROk(NonExhaustive::new(x)),
            Err(e) => RErr(RBoxError::new(e)),
        }
    }
}