rkyv_dyn 0.6.6

Trait object serialization for rkyv.

API Documentation

• rkyv, the core library
• rkyv_dyn, which adds trait object support to rkyv
• rkyv_typename, a type naming library

Book

• The rkyv book covers the motivation and architecture of rkyv

Sister Crates:

• bytecheck, which rkyv uses for validation
• ptr_meta, which rkyv uses for pointer manipulation

rkyv_dyn in action

use rkyv::{
    archived_value,
    de::deserializers::AllocDeserializer,
    ser::{
        serializers::AlignedSerializer,
        Serializer,
    },
    AlignedVec,
    Archive,
    Archived,
    Deserialize,
    Serialize,
};
use rkyv_dyn::archive_dyn;
use rkyv_typename::TypeName;

#[archive_dyn(deserialize)]
trait ExampleTrait {
    fn value(&self) -> String;
}

#[derive(Archive, Serialize, Deserialize)]
#[archive(derive(TypeName))]
struct StringStruct(String);

#[archive_dyn]
impl ExampleTrait for StringStruct {
    fn value(&self) -> String {
        self.0.clone()
    }
}

impl ExampleTrait for Archived<StringStruct> {
    fn value(&self) -> String {
        self.0.as_str().to_string()
    }
}

#[derive(Archive, Serialize, Deserialize)]
#[archive(derive(TypeName))]
struct IntStruct(i32);

#[archive_dyn(deserialize)]
impl ExampleTrait for IntStruct {
    fn value(&self) -> String {
        format!("{}", self.0)
    }
}

impl ExampleTrait for Archived<IntStruct> {
    fn value(&self) -> String {
        format!("{}", self.0)
    }
}

fn main() {
    let boxed_int = Box::new(IntStruct(42)) as Box<dyn SerializeExampleTrait>;
    let boxed_string = Box::new(StringStruct("hello world".to_string())) as Box<dyn SerializeExampleTrait>;
    let mut serializer = AlignedSerializer::new(AlignedVec::new());

    let int_pos = serializer.serialize_value(&boxed_int)
        .expect("failed to archive boxed int");
    let string_pos = serializer.serialize_value(&boxed_string)
        .expect("failed to archive boxed string");
    let buf = serializer.into_inner();

    let archived_int = unsafe { archived_value::<Box<dyn SerializeExampleTrait>>(buf.as_ref(), int_pos) };
    let archived_string = unsafe { archived_value::<Box<dyn SerializeExampleTrait>>(buf.as_ref(), string_pos) };
    assert_eq!(archived_int.value(), "42");
    assert_eq!(archived_string.value(), "hello world");

    let deserialized_int: Box<dyn SerializeExampleTrait> = archived_int.deserialize(&mut AllocDeserializer).unwrap();
    let deserialized_string: Box<dyn SerializeExampleTrait> = archived_string.deserialize(&mut AllocDeserializer).unwrap();
    assert_eq!(deserialized_int.value(), "42");
    assert_eq!(deserialized_string.value(), "hello world");
}