hecs-schedule 0.3.6

Provides shedulable systems and parallel execution for hecs
Documentation 
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///! This module works around the lifetimes for borrow when GAT isn't available
use std::marker::PhantomData;

use crate::{Context, Read, Result, SubWorld, Write};

use super::{ContextBorrow, MaybeRead, MaybeWrite};

/// Lifetime erasure in waiting of GAT
pub trait IntoBorrow {
    /// The borrow type
    type Borrow: for<'x> ContextBorrow<'x>;
}

/// Macro for implementing lifetime eliding IntoBorrow

macro_rules! impl_into_borrow {
    ($name: tt => $borrower: tt) => {
        #[doc(hidden)]
        pub struct $borrower<T>(PhantomData<T>);

        impl<T: 'static> IntoBorrow for $name<'_, T> {
            type Borrow = $borrower<T>;
        }

        impl<'a, T: 'static> ContextBorrow<'a> for $borrower<T> {
            type Target = $name<'a, T>;

            fn borrow(context: &'a Context) -> Result<Self::Target> {
                Self::Target::borrow(context)
            }
        }
    };
}

impl_into_borrow!(Read => Borrower);
impl_into_borrow!(Write => BorrowMut);
impl_into_borrow!(MaybeRead => MaybeBorrower);
impl_into_borrow!(MaybeWrite => MaybeBorrowerMut);
impl_into_borrow!(SubWorld => SubWorldBorrower);