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|
/// Declares a [`Part`].
///
/// Defines an empty struct type and derives all necessary instances to use it as a marker type for
/// parts.
///
/// This macro can define [`AbstractPart`]s using `part!(PartName);` or `part!(pub PartName);` and
/// [`Field`] parts using `part!(PartName: FieldType);` or `part!(pub PartName: FieldType);`.
#[macro_export]
macro_rules! part {
($part:ident) => { part!(@template $part () () ($crate::AbstractPart)); };
(pub $part:ident) => { part!(@template $part () (pub) ($crate::AbstractPart)); };
($part:ident<> : $field:ty) => { part!($part : $field); };
(pub $part:ident<> : $field:ty) => { part!(pub $part : $field); };
($part:ident<$($lt:lifetime),*> : $field:ty) => {
part!(@template $part ($($lt),*) () ($crate::Field<$field>) ($field));
};
(pub $part:ident<$($lt:lifetime),*> : $field:ty) => {
part!(@template $part ($($lt),*) (pub) ($crate::Field<$field>) ($field));
};
($part:ident : $field:ty) => { part!(@template $part () () ($crate::Field<$field>)); };
(pub $part:ident : $field:ty) => { part!(@template $part () (pub) ($crate::Field<$field>)); };
(@template $part:ident () ($($vis:tt)*) ($($part_type:tt)*)) => {
#[derive(Default)]
$($vis)* struct $part;
impl $crate::Part for $part {
type PartType = $($part_type)*;
}
impl $crate::PartSpec<$part> for $part {}
// TODO maybe constrain InnerPart
impl<InnerPart: $crate::Part> ::std::ops::BitOr<InnerPart> for $part {
type Output = $crate::Nested<$part, InnerPart>;
fn bitor(self, _rhs: InnerPart) -> Self::Output {
std::default::Default::default()
}
}
};
(@template $part:ident ($($lt:lifetime),*) ($($vis:tt)*) ($($part_type:tt)*) ($field:ty)) => {
#[derive(Default)]
$($vis)* struct $part<$($lt),*> {
phantom: ::std::marker::PhantomData<$field>,
}
#[allow(non_upper_case_globals)]
$($vis)* const $part: $part = $part { phantom: ::std::marker::PhantomData };
impl<$($lt),*> $crate::Part for $part<$($lt),*> {
type PartType = $($part_type)*;
}
part!(@spec_template $part ($($lt),*));
// TODO maybe constrain InnerPart
impl<$($lt),*, InnerPart: $crate::Part> ::std::ops::BitOr<InnerPart> for $part<$($lt),*> {
type Output = $crate::Nested<$part<$($lt),*>, InnerPart>;
fn bitor(self, _rhs: InnerPart) -> Self::Output {
std::default::Default::default()
}
}
};
(@spec_template $part:ident ($l:lifetime)) => {
impl<'a, 'b> $crate::PartSpec<$part<'a>> for $part<'b> {}
};
(@spec_template $part:ident ($l1:lifetime, $l2:lifetime)) => {
impl<'a1, 'a2, 'b1, 'b2> $crate::PartSpec<$part<'a1, 'a2>> for $part<'b1, 'b2> {}
};
(@spec_template $part:ident ($l1:lifetime, $l2:lifetime, $l3:lifetime)) => {
impl<'a1, 'a2, 'a3, 'b1, 'b2, 'b3>
$crate::PartSpec<$part<'a1, 'a2, 'a3>>
for $part<'b1, 'b2, 'b3> {}
};
(@spec_template $part:ident ($($tt:tt)*)) => {
// TODO avoid this limitation
compile_error!("parts with more than 3 lifetimes are not supported yet");
};
}
/// Concise syntax for partial reference types.
///
/// The first parameter is the reference target type, optionally preceded by a lifetime. The
/// following parameters are the referenced parts, each optionally preceded by the keyword `mut` to
/// indicate a mutable reference to that part. Nested parts can be specified using the pipe syntax
/// of [`nested_part`].
///
/// Examples:
/// * `partial!(Ty, PartA)` is `Const<PartA, Ref<Ty>>`
/// * `partial!('a Ty, mut PartA)` is `Mut<PartA, Ref<'a, Ty>>`
/// * `partial!(Ty, PartA, PartB, mut PartC)` is
/// `Const<PartA, Const<PartB, Mut<PartC, Ref<Ty>>`
/// * `partial!('a Ty, mut PartA | PartB)` is `Mut<Nested<PartA, PartB>, Ref<'a, Ty>>`
#[macro_export]
macro_rules! partial {
($target_lt:lifetime $target:ty) => { $crate::Ref<$target_lt, $target> };
($target_lt:lifetime $target:ty, $($parts:tt)*) => {
partial!(@extend $crate::Ref<$target_lt, $target>, $($parts)*)
};
($target:ty) => { $crate::Ref<$target> };
($target:ty, $($parts:tt)* ) => {
partial!(@extend $crate::Ref<$target>, $($parts)*)
};
(@extend $target:ty) => {$target};
(@extend $target:ty, ) => {$target};
(@extend $target:ty, mut $($part:ty)|* , $($rest:tt)*) => {
partial!(@extend $crate::Mut<$crate::nested_part!($($part)|*), $target>, $($rest)*)
};
(@extend $target:ty, mut $($part:ty)|*) => {
partial!(@extend $target, mut $($part)|*, )
};
(@extend $target:ty, $($part:ty)|* , $($rest:tt)*) => {
partial!(@extend $crate::Const<$crate::nested_part!($($part)|*), $target>, $($rest)*)
};
(@extend $target:ty, $($part:ty)|*) => {
partial!(@extend $target, $($part)|*, )
};
}
/// Expands `A | B | ... | Z` to `Nested<...Nested<A, B>, ..., Z>`
///
/// This mirrors the syntax for the expressions that can be passed to [`PartialRef`]'s part
/// functions.
#[macro_export]
macro_rules! nested_part {
($target:ty) => { $target };
($target:ty | $part:ty) => {
$crate::Nested<$target , $part>
};
($target:ty | $part:ty | $($subparts:ty)|*) => {
nested_part!($crate::Nested<$target , $part> | $($subparts)|*)
};
}
/// Helper macro for splitting a partial reference.
///
/// The statement `split_borrow!(target, rest = &(...) expr)` where `...` is a list of parts (same
/// syntax as used for [`partial`]) splits the partial reference returned by expr and binds the listed
/// parts to the identifier `target` and the remaining parts to the identifier `rest`. This is done
/// using [`PartialRef`]'s split_borrow method.
///
/// As shorter version is available as `split_borrow!(target = &(...) ident)` which is identical to
/// `split_borrow!(target, ident = &(...) ident)`. This shadows the existing partial reference with
/// a new binding.
#[macro_export]
macro_rules! split_borrow {
($target:ident = &($($parts:tt)*) $from:ident) => {
split_borrow!($target, $from = &($($parts)*) $from)
};
($target:ident, $rest:ident = &($($parts:tt)*) $from:expr) => {
#[allow(unused_variables, unused_mut)]
let (mut $target, mut $rest) = ($from).split_borrow::<partial!(_, $($parts)*), _>();
};
}
|
