shipyard 0.11.2

Entity Component System
Documentation 
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use crate::all_storages::AllStorages;
use crate::atomic_refcell::ARef;
use crate::borrow::{Borrow, BorrowInfo, WorldBorrow};
use crate::component::Unique;
use crate::error;
use crate::scheduler::info::TypeInfo;
use crate::tracking::TrackingTimestamp;
use crate::views::UniqueView;
use crate::world::World;
use alloc::vec::Vec;
use core::ops::Deref;

/// Shared view over a unique storage of a component with a default value.
///
/// If the component is not already present, its default value will be inserted.
pub struct UniqueOrDefaultView<'v, T: Unique + Default>(UniqueView<'v, T>);

impl<'v, T: Unique + Default> Deref for UniqueOrDefaultView<'v, T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<'v, T: Unique + Default + Send + Sync> WorldBorrow for UniqueOrDefaultView<'v, T> {
    type WorldView<'a> = UniqueOrDefaultView<'a, T>;

    fn world_borrow(
        world: &World,
        last_run: Option<TrackingTimestamp>,
        current: TrackingTimestamp,
    ) -> Result<Self::WorldView<'_>, error::GetStorage> {
        let all_storages = world
            .all_storages()
            .map_err(error::GetStorage::AllStoragesBorrow)?;

        match all_storages.borrow::<UniqueView<'_, T>>() {
            Ok(_) => {}
            Err(error::GetStorage::MissingStorage { .. }) => all_storages.add_unique(T::default()),
            Err(err) => return Err(err),
        };

        let (all_storages, all_borrow) = unsafe { ARef::destructure(all_storages) };

        let view = UniqueView::borrow(all_storages, Some(all_borrow), last_run, current)?;

        Ok(UniqueOrDefaultView(view))
    }
}

unsafe impl<'v, T: Unique + Default + Send + Sync> BorrowInfo for UniqueOrDefaultView<'v, T> {
    fn borrow_info(info: &mut Vec<TypeInfo>) {
        UniqueView::<T>::borrow_info(info);
    }

    fn enable_tracking(
        enable_tracking_fn: &mut Vec<fn(&AllStorages) -> Result<(), error::GetStorage>>,
    ) {
        UniqueView::<T>::enable_tracking(enable_tracking_fn);
    }
}