dump/restore variables

[qrnch-jan]

I want to serialize a table, and all its subdata, to a file. Then do the opposite operation (load the file, and deserialize it into a table).

Basically I'm looking to store the complete game state of a game engine in a Lua table, and I'm wondering if I can make the game's load/save feature a mere bincode serialization/deserialization (+ file I/O).

Is this possible with mlua? I'm able to serialize (using global just as an illustration; in practice it's a subtable):

let globals = lua.globals();
let encoded: Vec<u8> = bincode::serialize(&globals).unwrap();

But I'm unsure if it's possible to deserialize in a similar manner. The specific issue is that I load the bincode blob from a file into a Vec<u8> .. but then what?

[khvzak]

In general, you need an intermediate representation. Many crates include it (serde_json::Value, serde_yaml::Value and so on).
Otherwise there is an universal serde_value::Value.

I'm not sure that bincode would work as it cannot serialize dynamically sized objects (eg Lua hash tables).
But for ciborium the code would be:

    // Encode
    let value = lua.from_value_with::<ciborium::Value>(
        Value::Table(lua.globals()),
        DeserializeOptions::default()
            .deny_unsupported_types(false)
            .deny_recursive_tables(false),
    )?;
    let mut data = Vec::new();
    ciborium::into_writer(&value, &mut data).unwrap();

    // Decode back
    let value = ciborium::from_reader::<ciborium::Value, _>(&data[..]).unwrap();
    let lua_value = lua.to_value(&value)?;
    println!("{lua_value:#?}");