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use crate::marker::Destruct;
use crate::marker::Tuple;
/// Struct representing a closure with mutably borrowed data.
///
/// Example:
/// ```no_build
/// #![feature(const_mut_refs)]
/// use crate::const_closure::ConstFnMutClosure;
/// const fn imp(state: &mut i32, (arg,): (i32,)) -> i32 {
/// *state += arg;
/// *state
/// }
/// let mut i = 5;
/// let mut cl = ConstFnMutClosure::new(&mut i, imp);
///
/// assert!(7 == cl(2));
/// assert!(8 == cl(1));
/// ```
pub(crate) struct ConstFnMutClosure<CapturedData, Function> {
/// The Data captured by the Closure.
/// Must be either a (mutable) reference or a tuple of (mutable) references.
pub data: CapturedData,
/// The Function of the Closure, must be: Fn(CapturedData, ClosureArgs) -> ClosureReturn
pub func: Function,
}
impl<'a, CapturedData: ?Sized, Function> ConstFnMutClosure<&'a mut CapturedData, Function> {
/// Function for creating a new closure.
///
/// `data` is the a mutable borrow of data that is captured from the environment.
/// If you want Data to be a tuple of mutable Borrows, the struct must be constructed manually.
///
/// `func` is the function of the closure, it gets the data and a tuple of the arguments closure
/// and return the return value of the closure.
pub(crate) const fn new<ClosureArguments, ClosureReturnValue>(
data: &'a mut CapturedData,
func: Function,
) -> Self
where
Function: ~const Fn(&mut CapturedData, ClosureArguments) -> ClosureReturnValue,
{
Self { data, func }
}
}
macro_rules! impl_fn_mut_tuple {
($($var:ident)*) => {
#[allow(unused_parens)]
impl<'a, $($var,)* ClosureArguments: Tuple, Function, ClosureReturnValue> const
FnOnce<ClosureArguments> for ConstFnMutClosure<($(&'a mut $var),*), Function>
where
Function: ~const Fn(($(&mut $var),*), ClosureArguments) -> ClosureReturnValue+ ~const Destruct,
{
type Output = ClosureReturnValue;
extern "rust-call" fn call_once(mut self, args: ClosureArguments) -> Self::Output {
self.call_mut(args)
}
}
#[allow(unused_parens)]
impl<'a, $($var,)* ClosureArguments: Tuple, Function, ClosureReturnValue> const
FnMut<ClosureArguments> for ConstFnMutClosure<($(&'a mut $var),*), Function>
where
Function: ~const Fn(($(&mut $var),*), ClosureArguments)-> ClosureReturnValue,
{
extern "rust-call" fn call_mut(&mut self, args: ClosureArguments) -> Self::Output {
#[allow(non_snake_case)]
let ($($var),*) = &mut self.data;
(self.func)(($($var),*), args)
}
}
};
}
impl_fn_mut_tuple!(A);
impl_fn_mut_tuple!(A B);
impl_fn_mut_tuple!(A B C);
impl_fn_mut_tuple!(A B C D);
impl_fn_mut_tuple!(A B C D E);
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