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diff --git a/vendor/partial_ref/src/lib.rs b/vendor/partial_ref/src/lib.rs new file mode 100644 index 000000000..03d4f01e9 --- /dev/null +++ b/vendor/partial_ref/src/lib.rs @@ -0,0 +1,964 @@ +//! Type checked partial references. +//! +//! This crate provides type checked partial references for rust. Type checked partial references +//! are one solution to solve [interprocedural borrowing conflicts][interprocedural-conflicts]. +//! +//! # Tutorial +//! +//! With this crate it is possible to declare typed parts (using the [`part`] macro) and to assign +//! struct fields to these parts (by [deriving `PartialRefTarget`](partial_ref_derive)). +//! +//! ``` +//! use partial_ref::{part, PartialRefTarget}; +//! +//! part!(pub Neighbors: Vec<Vec<usize>>); +//! part!(pub Colors: Vec<usize>); +//! part!(pub Weights: Vec<f32>); +//! +//! #[derive(PartialRefTarget, Default)] +//! pub struct Graph { +//! #[part(Neighbors)] +//! pub neighbors: Vec<Vec<usize>>, +//! #[part(Colors)] +//! pub colors: Vec<usize>, +//! #[part(Weights)] +//! pub weights: Vec<f32>, +//! } +//! ``` +//! +//! It is then possible to convert a reference to a value using the [`IntoPartialRef`] and +//! [`IntoPartialRefMut`] traits, which are derived alongside PartialRefTarget. Note that a mutable +//! partial reference must itself be mutable for mutable access. +//! +//! ``` +//! # use partial_ref::{part, PartialRefTarget}; +//! # use partial_ref_tests::doctest_helpers::*; +//! use partial_ref::IntoPartialRefMut; +//! +//! let mut g = Graph::default(); +//! +//! let mut g_ref = g.into_partial_ref_mut(); +//! ``` +//! +//! You can access parts using the [`part`](PartialRef::part) and [`part_mut`](PartialRef::part_mut) +//! methods. +//! +//! ``` +//! # use partial_ref::{part, PartialRefTarget, IntoPartialRefMut}; +//! # use partial_ref_tests::doctest_helpers::*; +//! # let mut g = Graph::default(); +//! # let mut g_ref = g.into_partial_ref_mut(); +//! use partial_ref::PartialRef; +//! +//! g_ref.part_mut(Colors).extend(&[0, 1, 0]); +//! g_ref.part_mut(Weights).extend(&[0.25, 0.5, 0.75]); +//! +//! g_ref.part_mut(Neighbors).push(vec![1, 2]); +//! g_ref.part_mut(Neighbors).push(vec![0, 2]); +//! g_ref.part_mut(Neighbors).push(vec![0, 1]); +//! +//! assert_eq!(g_ref.part(Colors).len(), g_ref.part(Neighbors).len()); +//! assert_eq!(g_ref.part(Colors).len(), g_ref.part(Weights).len()); +//! ``` +//! +//! We can now write a function that takes parts of a reference. The type of such a partial +//! reference can be written using the [`partial`] macro, which expands to a combination of [`Mut`], +//! [`Const`] and [`Ref`]. Again the parameter `g` here must be mutable to allow mutable access to +//! the referenced value. To call such a function we use the [`borrow`](PartialRef::borrow) method, +//! which will re-borrow just the required parts. +//! +//! ``` +//! # use partial_ref::{part, PartialRefTarget, IntoPartialRefMut, PartialRef}; +//! # use partial_ref_tests::doctest_helpers::*; +//! # let mut g = example_graph(); +//! # let mut g_ref = g.into_partial_ref_mut(); +//! use partial_ref::partial; +//! +//! pub fn add_color_to_weight( +//! mut g: partial!(Graph, mut Weights, Colors), +//! index: usize, +//! ) { +//! g.part_mut(Weights)[index] += g.part(Colors)[index] as f32; +//! } +//! +//! add_color_to_weight(g_ref.borrow(), 1); +//! +//! assert_eq!(g_ref.part(Weights)[1], 1.5); +//! ``` +//! +//! So far everything could have been written using plain built-in references. This changes as soon +//! as we want to iterate over the neighbors while invoking our function. Usually we couldn't pass a +//! mutable reference to the graph while holding the iterator over the neighbors. +//! +//! This can be easily done using partial references which support splitting. Splitting means +//! turning a single reference into two references where each has a subset of parts, so that each +//! mutably referenced part belongs only to a single reference. This is done by the +//! [`split_borrow`](PartialRef::borrow) and [`split_part`](PartialRef::split_part) methods. +//! +//! ``` +//! # use partial_ref::{part, PartialRefTarget, IntoPartialRefMut, PartialRef, partial}; +//! # use partial_ref_tests::doctest_helpers::*; +//! # let mut g = example_graph(); +//! # let mut g_ref = g.into_partial_ref_mut(); +//! let (neighbors, mut g_ref) = g_ref.split_part_mut(Neighbors); +//! let (colors, mut g_ref) = g_ref.split_part(Colors); +//! +//! for (edges, &color) in neighbors.iter_mut().zip(colors.iter()) { +//! edges.retain(|&neighbor| colors[neighbor] != color); +//! +//! for &neighbor in edges.iter() { +//! add_color_to_weight(g_ref.borrow(), neighbor); +//! } +//! } +//! ``` +//! +//! This covers the basic functionality of this library. Beyond that this library also supports: +//! +//! * Partial references to nested structs using [`Nested`] and [`nested_part`]. +//! * Generic functions with bounds on available parts using [`HasPart`]. +//! +//! # Notes +//! +//! Some documented items are marked with *(internal)*. Typical code using this library doesn't +//! explicitly refer to them. Nevertheless they often appear in error messages and are thus part of +//! this documentation. These items also have to be public for the inference driven meta programming +//! to work. Code that is generic over parts of partial references might also need them. +//! +//! Many traits in this crate are marked as unsafe without documenting any requirements for +//! implementations. This does not mean they are safe to implement, but rather means that they are +//! not intended to be implemented outside of this library. Feel free to file an issue if you have a +//! good reason to implement them so the requirements can be documented. +//! +//! [interprocedural-conflicts]: http://smallcultfollowing.com/babysteps/blog/2018/11/01/after-nll-interprocedural-conflicts/ + +#[macro_use] +mod macros; + +pub use partial_ref_derive::PartialRefTarget; + +use std::marker::PhantomData; + +/// A type that can be the target of partial references. +/// +/// Implementations for this trait should be derived, see [`partial_ref_derive`]. +pub trait PartialRefTarget { + /// A partial reference will be represented by a pointer to this associated type. + /// + /// In most cases this is the implementing type itself. This is not a requirement though. In the + /// future, some features will introduce PartialRefTargets that have a different associated + /// `RawTarget` type. + type RawTarget: ?Sized; +} + +/// Helper trait to associate the target type with a [`PartialRef`] without needing a lifetime. +pub trait HasTarget { + /// The referenced type. + /// + // TODO add a warning that Target::RawTarget could be != Target when such a feature lands) + type Target: PartialRefTarget + ?Sized; +} + +/// A partial reference. +/// +/// This is implemented by variants of [`Ref`], [`Mut`] and [`Const`]. This is only implemented if the +/// parts of any contained [`Mut`] or [`Const`] are valid for the referenced type. +pub trait PartialRef<'a>: HasTarget + Sized { + /// Create a partial reference from a raw pointer. + /// + /// # Safety + /// This is unsafe for two reasons. It can be used to dereference a raw pointer, which is + /// already unsafe on its own, and it can be used to construct invalid partial references, for + /// example containing the same mutable part twice. Thus extra care is required when calling + /// this. + unsafe fn from_raw(ptr: *mut <Self::Target as PartialRefTarget>::RawTarget) -> Self; + + /// Access to the underlying raw pointer. + /// + /// Beware that this can be used even for an empty reference with no parts. Doing anything with + /// the resulting pointer is very likely unsafe, even if the partial reference is still in + /// scope. + fn get_raw(&self) -> *mut <Self::Target as PartialRefTarget>::RawTarget; + + /// Partially re-borrows a partial reference. + /// + /// This returns a new partial reference to the same value. The returned reference can have a + /// subset of the original reference's parts. + /// + /// A typical use case is passing a reference to a function that requires fewer parts than the + /// caller. + /// + /// Usually the type parameters can be inferred. + #[inline(always)] + fn borrow<BorrowedRef, SubsetIndex>(&'a mut self) -> BorrowedRef + where + BorrowedRef: PartialRef<'a, Target = Self::Target>, + Self: HasSubset<'a, BorrowedRef, SubsetIndex>, + { + unsafe { BorrowedRef::from_raw(self.get_raw()) } + } + + /// Access a part of the referenced value. + /// + /// This returns a plain reference to a single part. + /// + /// The parameter is only present for type inference, its value is ignored. As all parts + /// implement [`Default`] it is always possible to pass a default value, which is useful in + /// generic code. + /// + /// Usually the type parameters can be inferred. + #[inline(always)] + fn part<FieldPartSpec, FieldPart, PartIndex, FieldType>( + &'a self, + _part: FieldPartSpec, + ) -> &'a FieldType + where + FieldType: ?Sized, + FieldPart: Part<PartType = Field<FieldType>>, + FieldPartSpec: PartSpec<FieldPart>, + Self: PluckConst<'a, FieldPart, PartIndex>, + Self::Target: HasPart<FieldPart> + 'a, + { + unsafe { + <Const<FieldPart, Ref<'a, Self::Target>> as PartialRef<'a>>::from_raw(self.get_raw()) + .get_part() + } + } + + /// Mutable access to a part of the referenced value. + /// + /// This returns a plain mutable reference to a single part. + /// + /// The parameter is only present for type inference, its value is ignored. As all parts + /// implement [`Default`] it is always possible to pass a default value, which is useful in + /// generic code. + /// + /// Usually the type parameters can be inferred. + #[inline(always)] + fn part_mut<FieldPartSpec, FieldPart, PartIndex, FieldType>( + &'a mut self, + _part: FieldPartSpec, + ) -> &'a mut FieldType + where + FieldType: ?Sized, + FieldPart: Part<PartType = Field<FieldType>>, + FieldPartSpec: PartSpec<FieldPart>, + Self: PluckMut<'a, FieldPart, PartIndex>, + Self::Target: HasPart<FieldPart> + 'a, + { + unsafe { + <Mut<FieldPart, Ref<'a, Self::Target>> as PartialRef<'a>>::from_raw(self.get_raw()) + .get_part_mut() + } + } + + /// Partially re-borrows a partial reference, splitting off the remaining parts. + /// + /// This is equivalent to [`borrow`](PartialRef::borrow) but also returns a second partial + /// reference that contains all parts that can be used simultaneously with the re-borrowed + /// reference. + /// + /// This means that constant parts are contained in both references, while mutable parts that + /// are re-borrowed are missing from the second partial reference. Mutable parts that are + /// re-borrowed as constant parts are constant parts of both references. + /// + /// Usually the type parameters can be inferred. + #[inline(always)] + fn split_borrow<BorrowedRef, SubsetIndex>(&'a mut self) -> (BorrowedRef, Self::Remainder) + where + BorrowedRef: PartialRef<'a, Target = Self::Target>, + Self: HasSubset<'a, BorrowedRef, SubsetIndex>, + { + let ptr = self.get_raw(); + unsafe { (BorrowedRef::from_raw(ptr), Self::Remainder::from_raw(ptr)) } + } + + /// Access a part of the referenced value, splitting off the remaining parts. + /// + /// This is equivalent to [`part`](PartialRef::part) but also returns a partial reference as + /// described in [`split_borrow`](PartialRef::split_borrow). + #[inline(always)] + fn split_part<FieldPartSpec, FieldPart, PartIndex, FieldType>( + &'a mut self, + _part: FieldPartSpec, + ) -> (&'a FieldType, Self::Remainder) + where + FieldType: ?Sized, + FieldPart: Part<PartType = Field<FieldType>>, + FieldPartSpec: PartSpec<FieldPart>, + Self: PluckConst<'a, FieldPart, PartIndex>, + Self::Target: HasPart<FieldPart> + 'a, + { + let ptr = self.get_raw(); + unsafe { + ( + <Const<FieldPart, Ref<'a, Self::Target>> as PartialRef<'a>>::from_raw(ptr) + .get_part(), + Self::Remainder::from_raw(ptr), + ) + } + } + + /// Mutable access to a part of the referenced value, splitting off the remaining parts. + /// + /// This is equivalent to [`part_mut`](PartialRef::part_mut) but also returns a partial + /// reference as described in [`split_borrow`](PartialRef::split_borrow). + #[inline(always)] + fn split_part_mut<FieldPartSpec, FieldPart, PartIndex, FieldType>( + &'a mut self, + _part: FieldPartSpec, + ) -> (&'a mut FieldType, Self::Remainder) + where + FieldType: ?Sized, + FieldPart: Part<PartType = Field<FieldType>>, + FieldPartSpec: PartSpec<FieldPart>, + Self: PluckMut<'a, FieldPart, PartIndex>, + Self::Target: HasPart<FieldPart> + 'a, + { + let ptr = self.get_raw(); + unsafe { + ( + <Mut<FieldPart, Ref<'a, Self::Target>> as PartialRef<'a>>::from_raw(ptr) + .get_part_mut(), + Self::Remainder::from_raw(ptr), + ) + } + } +} + +/// Construction of partial references. +/// +/// See also [`IntoPartialRefMut`]. +/// +/// This trait gets an automatic implementation for references (mutable or immutable) to any type +/// that has a derive statement for [`PartialRefTarget`]. Usually there is no need to implement this +/// trait manually. +pub trait IntoPartialRef<'a> { + type Ref: PartialRef<'a>; + + /// Convert a mutable or immutable reference into a partial reference. + fn into_partial_ref(self) -> Self::Ref; +} + +/// Construction of partial references from mutable references. +/// +/// This has an implementation for mutable references that implement [`IntoPartialRefMut`]. It +/// performs the same operation as [`IntoPartialRefMut`] but is only implemented for mutable +/// references. This is useful as it allows writing `value.into_partial_ref_mut()` instead of `(&mut +/// value).into_partial_ref_mut()` using auto referencing of method calls. Using just +/// [`value.into_partial_ref()`] would result in an immutable reference. +pub trait IntoPartialRefMut<'a>: IntoPartialRef<'a> { + /// Convert a mutable reference into a partial reference. + fn into_partial_ref_mut(self) -> Self::Ref; +} + +impl<'a, T> IntoPartialRefMut<'a> for &'a mut T +where + Self: IntoPartialRef<'a>, +{ + fn into_partial_ref_mut(self) -> Self::Ref { + self.into_partial_ref() + } +} + +/// *(internal)* Split a part into nested parts. +/// +/// This is used to implement splitting of nested parts. +pub unsafe trait SplitIntoParts<'a, ContainingPart, Reference: PartialRef<'a>> { + /// A partial reference that has all the parts `Reference` and all parts of `Self` nested in + /// `ContainingPart` as constant parts. + type Result: PartialRef<'a, Target = Reference::Target>; + /// A partial reference that has all the parts `Reference` and all parts of `Self` nested in + /// `ContainingPart` as mutable parts. + type ResultMut: PartialRef<'a, Target = Reference::Target>; +} + +/// An empty partial reference borrowing no parts. +/// +/// Partial references with a non-empty set of borrowed parts are built by nesting this type within +/// the [`Mut`] and [`Const`] types. +#[repr(transparent)] +pub struct Ref<'a, Target: PartialRefTarget + ?Sized> { + ptr: *mut Target::RawTarget, + phantom: PhantomData<&'a mut Target>, +} + +impl<'a, Target: PartialRefTarget + ?Sized> HasTarget for Ref<'a, Target> { + type Target = Target; +} + +/// An empty reference to a valid target is a valid reference. +impl<'a, 'b: 'a, Target: PartialRefTarget + ?Sized> PartialRef<'a> for Ref<'b, Target> { + #[inline(always)] + unsafe fn from_raw(ptr: *mut <Self::Target as PartialRefTarget>::RawTarget) -> Self { + Ref { + ptr, + phantom: PhantomData, + } + } + + #[inline(always)] + fn get_raw(&self) -> *mut <Self::Target as PartialRefTarget>::RawTarget { + self.ptr + } +} + +/// An empty reference contains no mutable parts and thus is safe to clone. +impl<'a, Target: PartialRefTarget> Copy for Ref<'a, Target> {} + +/// An empty reference contains no mutable parts and thus is safe to clone. +impl<'a, Target: PartialRefTarget> Clone for Ref<'a, Target> { + #[inline(always)] + fn clone(&self) -> Self { + *self + } +} + +/// A mutable part of a partial reference. +#[repr(transparent)] +pub struct Mut<Part, Reference: HasTarget> { + ptr: *mut <<Reference as HasTarget>::Target as PartialRefTarget>::RawTarget, + phantom: PhantomData<(Reference, Part)>, +} + +impl<'a, SomePart: Part, Reference: PartialRef<'a>> HasTarget for Mut<SomePart, Reference> +where + Reference::Target: HasPart<SomePart>, +{ + type Target = Reference::Target; +} + +/// Extending a valid reference by a mutable part is still a valid reference when the reference +/// target has such a part. +impl<'a, SomePart: Part, Reference: PartialRef<'a>> PartialRef<'a> for Mut<SomePart, Reference> +where + Reference::Target: HasPart<SomePart>, +{ + #[inline(always)] + unsafe fn from_raw(ptr: *mut <Self::Target as PartialRefTarget>::RawTarget) -> Self { + Mut { + ptr, + phantom: PhantomData, + } + } + + #[inline(always)] + fn get_raw(&self) -> *mut <Self::Target as PartialRefTarget>::RawTarget { + self.ptr + } +} + +/// A constant (immutable) part of a partial reference. +#[repr(transparent)] +pub struct Const<Part, Reference: HasTarget> { + ptr: *mut <<Reference as HasTarget>::Target as PartialRefTarget>::RawTarget, + phantom: PhantomData<(Reference, Part)>, +} + +impl<'a, SomePart: Part, Reference: PartialRef<'a>> HasTarget for Const<SomePart, Reference> +where + Reference::Target: HasPart<SomePart>, +{ + type Target = Reference::Target; +} + +/// Extending a valid reference by a constant part is still a valid reference when the reference +/// target has such a part. +impl<'a, SomePart: Part, Reference: PartialRef<'a>> PartialRef<'a> for Const<SomePart, Reference> +where + Reference::Target: HasPart<SomePart>, +{ + #[inline(always)] + unsafe fn from_raw(ptr: *mut <Self::Target as PartialRefTarget>::RawTarget) -> Self { + Const { + ptr, + phantom: PhantomData, + } + } + + #[inline(always)] + fn get_raw(&self) -> *mut <Self::Target as PartialRefTarget>::RawTarget { + self.ptr + } +} + +/// A reference containing just constant parts is safe to clone. +impl<SomePart, Reference: Copy + HasTarget> Copy for Const<SomePart, Reference> {} + +/// A reference containing just constant parts is safe to clone. +impl<SomePart, Reference: Copy + HasTarget> Clone for Const<SomePart, Reference> { + #[inline(always)] + fn clone(&self) -> Self { + *self + } +} + +impl<'a, SomePart, Target, FieldType> Const<SomePart, Ref<'a, Target>> +where + FieldType: ?Sized, + SomePart: Part<PartType = Field<FieldType>>, + Target: ?Sized, + Target: HasPart<SomePart>, +{ + /// Only available on single part references, used to implement the more general + /// [`part`](PartialRef::part) method of [`PartialRef`]. + #[inline(always)] + fn get_part(self) -> &'a FieldType { + unsafe { &*Target::part_ptr(self.get_raw() as *const _) } + } +} + +impl<'a, SomePart, Target, FieldType> Mut<SomePart, Ref<'a, Target>> +where + FieldType: ?Sized, + SomePart: Part<PartType = Field<FieldType>>, + Target: ?Sized, + Target: HasPart<SomePart>, +{ + /// Only available on single part references, used to implement the more general + /// [`part_mut`](PartialRef::part_mut) method of [`PartialRef`] + #[inline(always)] + fn get_part_mut(self) -> &'a mut FieldType { + unsafe { &mut *Target::part_ptr_mut(self.get_raw()) } + } +} + +// Parts + +/// Marker types for a part of a type. +/// +/// Types implementing this trait are usually created using the [`part`] macro. +/// +/// A type implementing this trait is used to identify a part of a reference target. Multiple +/// different reference targets can have a part identified by the same [`Part`] (see also +/// [`HasPart`]). A part has an associated [`PartType`], which determines what can be done with a +/// part. +pub trait Part: Default { + type PartType: PartType; +} + +/// Helper trait to strip lifetimes from a part. +/// +/// Every part `SomePart<'a, ...>` should implement `PartSpec<SomePart<'b, ...>>`. This is used by +/// the [`part`](PartialRef::part), [`part_mut`](PartialRef::part_mut), +/// [`split_part`](PartialRef::split_part) and [`split_part_mut`](PartialRef::split_part_mut) +/// functions. This allows the passed parameter to have a different lifetime than the accessed part. +/// This in turn enables part selection using globals with static lifetimes as declared by the +/// [`part`] macro. +pub trait PartSpec<Part> {} + +/// Implemented when a reference target has a part. +/// +/// This trait provides methods for unchecked access to a part of a reference target. +/// Implementations for this are automatically created when deriving PartialRefTarget. +pub trait HasPart<SomePart: Part>: PartialRefTarget { + /// Given a constant pointer to a target, produce a constant pointer to a part of it. + /// + /// # Safety + /// Implementations may construct a temporary reference to ptr, which thus must be valid. + unsafe fn part_ptr(ptr: *const Self::RawTarget) -> <SomePart::PartType as PartType>::Ptr; + /// Given a mutable pointer to a target, produce a mutable pointer to a part of it. + /// + /// # Safety + /// Implementations may construct a temporary reference to ptr, which thus must be valid. + unsafe fn part_ptr_mut(ptr: *mut Self::RawTarget) -> <SomePart::PartType as PartType>::PtrMut; +} + +/// Type of a part, determines what can be done with a part. +/// +/// Common part types are [`Field`] and [`AbstractPart`]. +pub trait PartType { + /// Type that can be produced from a constant pointer to a reference target. + type Ptr; + /// Type that can be produced from a mutable pointer to a reference target. + type PtrMut; +} + +/// Type of a part that corresponds to a struct field. +/// +/// Partial references containing a part of this type provide access to that field. +pub struct Field<FieldType: ?Sized>(PhantomData<FieldType>); + +impl<FieldType: ?Sized> PartType for Field<FieldType> { + type Ptr = *const FieldType; + type PtrMut = *mut FieldType; +} + +/// Type of an abstract part. +/// +/// Partial reference keep track of an abstract part, without providing any operations on it. +pub struct AbstractPart; + +impl PartType for AbstractPart { + type Ptr = (); + type PtrMut = (); +} + +/// A nested part. +/// +/// A nested part can be constructed from an outer part and an inner part. The outer part must be a +/// [`Field`] part, and the field's type must be a [`PartialRefTarget`] having the the inner part +/// ([`HasPart`]). +/// +/// When nesting multiple times, the nested part should always be the outer part. This isn't +/// enforced, but some operations are only supported in that case. +#[derive(Default)] +pub struct Nested<Outer, Inner>(Outer, Inner); + +/// Create default values for nested parts. +/// +/// These are useful as parameters to pass to [`PartialRef`]'s part functions. +impl<NewInnerPart: Part, Outer: Part, Inner: Part> std::ops::BitOr<NewInnerPart> + for Nested<Outer, Inner> +{ + type Output = Nested<Nested<Outer, Inner>, NewInnerPart>; + + fn bitor(self, _rhs: NewInnerPart) -> Self::Output { + std::default::Default::default() + } +} + +/// A nested part is itself a part. +impl<Outer, OuterFieldType, Inner> Part for Nested<Outer, Inner> +where + Outer: Part<PartType = Field<OuterFieldType>>, + Inner: Part, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<Inner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, +{ + type PartType = Inner::PartType; +} + +impl<Outer, Inner, OuterS, InnerS> PartSpec<Nested<OuterS, InnerS>> for Nested<Outer, Inner> +where + Outer: PartSpec<OuterS>, + Inner: PartSpec<InnerS>, +{ +} + +/// A reference has a nested part if it has the outer part and the nested part is valid. +impl<Reference, Outer, OuterFieldType, Inner> HasPart<Nested<Outer, Inner>> for Reference +where + Reference: ?Sized, + Reference: HasPart<Outer>, + Outer: Part<PartType = Field<OuterFieldType>>, + Inner: Part, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<Inner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, +{ + #[inline(always)] + unsafe fn part_ptr(ptr: *const Self::RawTarget) -> <Inner::PartType as PartType>::Ptr { + <OuterFieldType as HasPart<Inner>>::part_ptr(<Self as HasPart<Outer>>::part_ptr(ptr)) + } + + #[inline(always)] + unsafe fn part_ptr_mut(ptr: *mut Self::RawTarget) -> <Inner::PartType as PartType>::PtrMut { + <OuterFieldType as HasPart<Inner>>::part_ptr_mut(<Self as HasPart<Outer>>::part_ptr_mut( + ptr, + )) + } +} + +// Type level logic for subsetting +// This is inspired by the `frunk` crate + +/// *(internal)* Select the first part. +pub struct IndexHere; + +/// *(internal)* Skip the first part. +pub struct IndexNext<Index>(Index); + +/// *(internal)* Split the first part. +pub struct IndexSplit<NestedPartIndex, Index>(NestedPartIndex, Index); + +/// *(internal)* Extracts the constant part `PluckedPart` at position `Index` from the partial +/// reference having this trait, leaving `Self::Remainder`. +/// +/// Plucking a constant part still leaves the part in the remaining reference, but will change it +/// from mutable to constant. +/// +/// The `Index` type can be inferred. +pub unsafe trait PluckConst<'a, PluckedPart, Index>: PartialRef<'a> { + /// The partial reference left after plucking. + type Remainder: PartialRef<'a, Target = Self::Target>; +} + +/// *(internal)* Extracts the mutable part `PluckedPart` at position `Index` from the partial +/// reference having this trait, leaving `Self::Remainder`. +/// +/// Plucking a mutable part removes it from the remaining reference. +/// +/// The `Index` type can be inferred. +pub unsafe trait PluckMut<'a, PluckedPart, Index>: PartialRef<'a> { + /// The partial reference left after plucking. + type Remainder: PartialRef<'a, Target = Self::Target>; +} + +/// *(internal)* Plucks the outermost constant part. +unsafe impl<'a, PluckedPart, Reference> PluckConst<'a, PluckedPart, IndexHere> + for Const<PluckedPart, Reference> +where + PluckedPart: Part, + Reference: PartialRef<'a>, + Reference::Target: HasPart<PluckedPart>, +{ + type Remainder = Const<PluckedPart, Reference>; +} + +/// *(internal)* Plucks the first part, converting it from mutable to constant. +unsafe impl<'a, PluckedPart, Reference> PluckConst<'a, PluckedPart, IndexHere> + for Mut<PluckedPart, Reference> +where + PluckedPart: Part, + Reference: PartialRef<'a>, + Reference::Target: HasPart<PluckedPart>, +{ + type Remainder = Const<PluckedPart, Reference>; +} + +/// *(internal)* Plucks the first mutable part. +unsafe impl<'a, PluckedPart, Reference> PluckMut<'a, PluckedPart, IndexHere> + for Mut<PluckedPart, Reference> +where + PluckedPart: Part, + Reference: PartialRef<'a>, + Reference::Target: HasPart<PluckedPart>, +{ + type Remainder = Reference; +} + +/// *(internal)* Skips the constant first part while plucking a constant part. +unsafe impl<'a, PluckedPart, SkippedPart, Reference, Index> + PluckConst<'a, PluckedPart, IndexNext<Index>> for Const<SkippedPart, Reference> +where + PluckedPart: Part, + SkippedPart: Part, + Reference::Target: HasPart<PluckedPart>, + Reference::Target: HasPart<SkippedPart>, + Reference: PluckConst<'a, PluckedPart, Index>, +{ + type Remainder = Const<SkippedPart, Reference::Remainder>; +} + +/// *(internal)* Skips the mutable first part while plucking a constant part. +unsafe impl<'a, PluckedPart, SkippedPart, Reference, Index> + PluckConst<'a, PluckedPart, IndexNext<Index>> for Mut<SkippedPart, Reference> +where + PluckedPart: Part, + SkippedPart: Part, + Reference::Target: HasPart<PluckedPart>, + Reference::Target: HasPart<SkippedPart>, + Reference: PluckConst<'a, PluckedPart, Index>, +{ + type Remainder = Mut<SkippedPart, Reference::Remainder>; +} + +/// *(internal)* Skips the constant first part while plucking a mutable part. +unsafe impl<'a, PluckedPart, SkippedPart, Reference, Index> + PluckMut<'a, PluckedPart, IndexNext<Index>> for Const<SkippedPart, Reference> +where + PluckedPart: Part, + SkippedPart: Part, + Reference::Target: HasPart<PluckedPart>, + Reference::Target: HasPart<SkippedPart>, + Reference: PluckMut<'a, PluckedPart, Index>, +{ + type Remainder = Const<SkippedPart, Reference::Remainder>; +} + +/// *(internal)* Skips the mutable first part while plucking a mutable part. +unsafe impl<'a, PluckedPart, SkippedPart, Reference, Index> + PluckMut<'a, PluckedPart, IndexNext<Index>> for Mut<SkippedPart, Reference> +where + PluckedPart: Part, + SkippedPart: Part, + Reference::Target: HasPart<PluckedPart>, + Reference::Target: HasPart<SkippedPart>, + Reference: PluckMut<'a, PluckedPart, Index>, +{ + type Remainder = Mut<SkippedPart, Reference::Remainder>; +} + +/// *(internal)* Pluck a mutable nested subpart of the mutable first part. +/// +/// This leaves all other subparts in the remaining reference. +unsafe impl< + 'a, + ContainingPart, + PluckedOuter, + PluckedInner, + Reference, + NestedPartIndex, + Index, + OuterFieldType, + ContainingFieldType, + > PluckMut<'a, Nested<PluckedOuter, PluckedInner>, IndexSplit<NestedPartIndex, Index>> + for Mut<ContainingPart, Reference> +where + PluckedOuter: Part<PartType = Field<OuterFieldType>>, + PluckedInner: Part, + ContainingPart: Part<PartType = Field<ContainingFieldType>>, + ContainingFieldType: SplitIntoParts<'a, ContainingPart, Reference>, + ContainingFieldType: ?Sized, + ContainingFieldType::ResultMut: PluckMut<'a, Nested<PluckedOuter, PluckedInner>, Index>, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<PluckedInner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, + Reference: PartialRef<'a>, + Reference::Target: HasPart<ContainingPart>, + ContainingPart: ContainsNestedPart<PluckedOuter, NestedPartIndex>, +{ + type Remainder = <ContainingFieldType::ResultMut as PluckMut< + 'a, + Nested<PluckedOuter, PluckedInner>, + Index, + >>::Remainder; +} + +/// *(internal)* Pluck a constant nested subpart of the mutable first part. +/// +/// This leaves all other subparts as mutable in the remaining reference. +unsafe impl< + 'a, + ContainingPart, + PluckedOuter, + PluckedInner, + Reference, + NestedPartIndex, + Index, + OuterFieldType, + ContainingFieldType, + > PluckConst<'a, Nested<PluckedOuter, PluckedInner>, IndexSplit<NestedPartIndex, Index>> + for Mut<ContainingPart, Reference> +where + PluckedOuter: Part<PartType = Field<OuterFieldType>>, + PluckedInner: Part, + ContainingPart: Part<PartType = Field<ContainingFieldType>>, + ContainingFieldType: SplitIntoParts<'a, ContainingPart, Reference>, + ContainingFieldType: ?Sized, + ContainingFieldType::ResultMut: PluckConst<'a, Nested<PluckedOuter, PluckedInner>, Index>, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<PluckedInner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, + Reference: PartialRef<'a>, + Reference::Target: HasPart<ContainingPart>, + ContainingPart: ContainsNestedPart<PluckedOuter, NestedPartIndex>, +{ + type Remainder = <ContainingFieldType::ResultMut as PluckConst< + 'a, + Nested<PluckedOuter, PluckedInner>, + Index, + >>::Remainder; +} + +/// *(internal)* Pluck a constant nested subpart of the constant first part. +unsafe impl< + 'a, + ContainingPart, + PluckedOuter, + PluckedInner, + Reference, + NestedPartIndex, + Index, + OuterFieldType, + ContainingFieldType, + > PluckConst<'a, Nested<PluckedOuter, PluckedInner>, IndexSplit<NestedPartIndex, Index>> + for Const<ContainingPart, Reference> +where + PluckedOuter: Part<PartType = Field<OuterFieldType>>, + PluckedInner: Part, + ContainingPart: Part<PartType = Field<ContainingFieldType>>, + ContainingFieldType: SplitIntoParts<'a, ContainingPart, Reference>, + ContainingFieldType: ?Sized, + ContainingFieldType::ResultMut: PluckConst<'a, Nested<PluckedOuter, PluckedInner>, Index>, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<PluckedInner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, + Reference: PartialRef<'a>, + Reference::Target: HasPart<ContainingPart>, + ContainingPart: ContainsNestedPart<PluckedOuter, NestedPartIndex>, +{ + type Remainder = Const<ContainingPart, Reference>; +} + +/// *(internal)* Index for the empty subset. +pub struct SubsetIndexEnd; + +/// *(internal)* Construct a subset index from a part index and another subset index. +pub struct SubsetIndexCons<PartIndex, TailIndex>(PartIndex, TailIndex); + +/// *(internal)* Asserts that the parts of the partial reference `Reference` are a subset of the +/// parts of the partial reference having this trait. +/// +/// A list of parts is considered a subset if they can be plucked in sequence. +pub unsafe trait HasSubset<'a, Reference, SubsetIndex>: PartialRef<'a> { + type Remainder: PartialRef<'a, Target = Self::Target>; +} + +/// *(internal)* Every reference has the empty reference as subset. +unsafe impl<'a, Reference> HasSubset<'a, Ref<'a, Reference::Target>, SubsetIndexEnd> for Reference +where + Reference: PartialRef<'a>, +{ + type Remainder = Reference; +} + +/// *(internal)* To have a reference with a constant first part as subset, pluck that part and make +/// sure the remaining references are in a subset relation. +unsafe impl<'a, SubsetPart, Reference, PluckedRef, PartIndex, TailIndex> + HasSubset<'a, Const<SubsetPart, Reference>, SubsetIndexCons<PartIndex, TailIndex>> + for PluckedRef +where + PluckedRef: PluckConst<'a, SubsetPart, PartIndex>, + <PluckedRef as PluckConst<'a, SubsetPart, PartIndex>>::Remainder: + HasSubset<'a, Reference, TailIndex>, + Reference: HasTarget, +{ + type Remainder = + <<PluckedRef as PluckConst<'a, SubsetPart, PartIndex>>::Remainder as HasSubset< + 'a, + Reference, + TailIndex, + >>::Remainder; +} + +/// *(internal)* To have a reference with a mutable first part as subset, pluck that part and make +/// sure the remaining references are in a subset relation. +unsafe impl<'a, SubsetPart, Reference, PluckedRef, PartIndex, TailIndex> + HasSubset<'a, Mut<SubsetPart, Reference>, SubsetIndexCons<PartIndex, TailIndex>> for PluckedRef +where + PluckedRef: PluckMut<'a, SubsetPart, PartIndex>, + <PluckedRef as PluckMut<'a, SubsetPart, PartIndex>>::Remainder: + HasSubset<'a, Reference, TailIndex>, + Reference: HasTarget, +{ + type Remainder = + <<PluckedRef as PluckMut<'a, SubsetPart, PartIndex>>::Remainder as HasSubset< + 'a, + Reference, + TailIndex, + >>::Remainder; +} + +// Nesting helpers + +/// *(internal)* Check whether a part is nested inside another part. +pub trait ContainsNestedPart<NestedPart, Index>: Part {} + +/// *(internal)* A part contains itself as a nested part. +impl<NestedPart> ContainsNestedPart<NestedPart, IndexHere> for NestedPart where NestedPart: Part {} + +/// *(internal)* A part contains a nested part if it contains the outer part of the nested part. +impl<NestedPart, Outer, Inner, OuterFieldType, Index> + ContainsNestedPart<Nested<Outer, Inner>, IndexNext<Index>> for NestedPart +where + NestedPart: Part, + Inner: Part, + NestedPart: ContainsNestedPart<Outer, Index>, + Outer: Part<PartType = Field<OuterFieldType>>, + OuterFieldType: ?Sized, + OuterFieldType: HasPart<Inner>, + OuterFieldType: PartialRefTarget<RawTarget = OuterFieldType>, +{ +} |