Use Lua as an Bevy-Engine asset

bevy_asset_lua.rs

use bevy::asset::{AssetLoader, BoxedFuture, LoadContext, LoadedAsset};
use mlua::prelude::*;
use std::marker::PhantomData;

pub trait LuaFile: Sized {
    fn new(lua: std::sync::Mutex<Lua>) -> Self;
}


/// Loads Text as an asset
pub struct LuaFileAssetLoader<A: bevy::asset::Asset + LuaFile> {
    pub extensions: Vec<&'static str>,
    pub _marker: PhantomData<A>
}

impl<A: bevy::asset::Asset + LuaFile> Default for LuaFileAssetLoader<A> {
    fn default() -> Self {
        Self {
            extensions: vec!["lua"],
            _marker: PhantomData::default()
        }
    }
}


impl<A: bevy::asset::Asset + LuaFile> AssetLoader for LuaFileAssetLoader<A> {
    fn load<'a>(
        &'a self,
        bytes: &'a [u8],
        load_context: &'a mut LoadContext,
    ) -> BoxedFuture<'a, Result<(), anyhow::Error>> {
        return Box::pin(async move {
            let code = String::from_utf8(Vec::from(bytes))?;
            let lua = Lua::new();
            lua.load(&code)
                .exec()
                .expect("Expected correct lua language file");

            lua.gc_stop();

            let lua = std::sync::Mutex::new(lua);

            load_context.set_default_asset(LoadedAsset::new(A::new(lua)));
            Ok(())
        });
    }

    fn extensions(&self) -> &[&str] {
        return &self.extensions;
    }
}