rkyv_dyn 0.3.1

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

rkyv_dyn in action

use rkyv::{
    Aligned,
    Archive,
    ArchiveBuffer,
    Archived,
    archived_value,
    Write,
};
use rkyv_dyn::archive_dyn;
use rkyv_typename::TypeName;

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

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

#[archive_dyn]
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 ArchiveExampleTrait>;
    let boxed_string = Box::new(StringStruct("hello world".to_string())) as Box<dyn ArchiveExampleTrait>;

    let mut writer = ArchiveBuffer::new(Aligned([0u8; 256]));
    let int_pos = writer.archive(&boxed_int)
        .expect("failed to archive boxed int");
    let string_pos = writer.archive(&boxed_string)
        .expect("failed to archive boxed string");
    let buf = writer.into_inner();

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