BTreeMap requires Archived keys #585
Description
Hi. I'm trying to use BTreeMap and.. is it just me or does it seem like ArchivedBTreeMap is really hard to use? It's get method demands the archived key type, which is sometimes quite hard to construct.
Here's a simple case (key is u32) where it would have been nice to just use the unarchived key type, but making the archived flavor is easy enough:
use std::collections::BTreeMap;
#[derive(rkyv::Archive, rkyv::Serialize)]
struct Example {
m: BTreeMap<u32, u32>,
}
fn main() {
let value = Example { m: BTreeMap::new() };
let bytes = rkyv::to_bytes::<rkyv::rancor::Error>(&value).unwrap();
println!("{bytes:?}");
let archived = rkyv::access::<ArchivedExample, rkyv::rancor::Error>(&bytes).unwrap();
let want: u32 = 42;
// PROBLEM: expected `&u32_le`, found `&u32`
// let _found = archived.m.get(&want);
let _found = archived.m.get(&rkyv::rend::u32_le::from_native(want));
}However, it just gets harder and harder from there. Simply wrapping the u32 in a little struct makes constructing the ArchivedKey extremely inconvenient.
(Adding #[rkyv(compare(...)], or deriving just about anything that might be relevant, is of no help.)
use std::collections::BTreeMap;
#[derive(
Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, rkyv::Archive, rkyv::Serialize, Debug,
)]
#[rkyv(derive(Ord, PartialOrd, Eq, PartialEq, Hash, Debug))]
#[rkyv(compare(PartialOrd, PartialEq))]
struct Key(u32);
#[derive(rkyv::Archive, rkyv::Serialize)]
struct Example {
m: BTreeMap<Key, u32>,
}
fn main() {
let value = Example {
m: BTreeMap::from_iter([(Key(42), 13)]),
};
let bytes = rkyv::to_bytes::<rkyv::rancor::Error>(&value).unwrap();
let archived = rkyv::access::<ArchivedExample, rkyv::rancor::Error>(&bytes).unwrap();
let want: Key = Key(42);
// PROBLEM: expected `&ArchivedKey`, found `&Key`
// let _found = archived.m.get(&want);
// iteration still works, and `k` here *is* an `&ArchivedKey`, but I wanted lookup
for (k, v) in archived.m.iter() {
if k == &want {
println!("found {v}");
}
}
}How am I supposed to call ArchivedBTreeMap::get?