tuplemagic 0.1.3

Utilities for manipulating tuples through various operations like mapping, filtering, nesting, and reducing
Documentation 
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use crate::nest::{TupleNest, TupleUnnest};
use crate::TypeMap;

#[doc(hidden)]
pub trait TupleMapper {
    type Output;
}

impl<TUPLE, PREDICATE> TupleMapper for (TUPLE, PREDICATE)
where
    TUPLE: TupleNest,
    <TUPLE as TupleNest>::Nested: TypeMap<PREDICATE>,
    <<TUPLE as TupleNest>::Nested as TypeMap<PREDICATE>>::Mapped: TupleUnnest,
{
    type Output =
        <<<TUPLE as TupleNest>::Nested as TypeMap<PREDICATE>>::Mapped as TupleUnnest>::Unnested;
}

/// Perform a mapping operation on a tuple using the given predicate type (a
/// [`TypeMap`] that returns a mapped type).
///
/// ```
/// # use tuplemagic::{TypeMap, tuple_mapper};
/// type T = (Option<u8>, Option<u16>, Option<()>);
/// struct RemoveOption {}
/// impl<T> TypeMap<RemoveOption> for Option<T> {
///     type Mapped = T;
/// }
///
/// type U = tuple_mapper!(RemoveOption::map(T));
/// let _: (u8, u16, ()) = U::default();
/// ```
#[macro_export]
macro_rules! tuple_mapper {
    ($predicate:ident::map($ty:ty)) => {
        <($ty, $predicate) as $crate::__macro_support::TupleMapper>::Output
    };
}