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// Copyright 2016 Amanieu d'Antras
//
// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
// http://opensource.org/licenses/MIT>, at your option. This file may not be
// copied, modified, or distributed except according to those terms.
use IntrusivePointer;
/// Trait for a adapter which allows a type to be inserted into an intrusive
/// collection. The `Link` type contains the collection-specific metadata which
/// allows an object to be inserted into an intrusive collection. This type
/// needs to match the collection type (eg. `LinkedListLink` for inserting
/// in a `LinkedList`).
///
/// `Value` is the actual object type managed by the collection. This type will
/// typically have an instance of `Link` as a struct field.
///
/// `Pointer` is a pointer type which "owns" an object of type `Value`.
/// Operations which insert an element into an intrusive collection will accept
/// such a pointer and operations which remove an element will return this type.
///
/// A single object type may have multiple adapters, which allows it to be part
/// of multiple intrusive collections simultaneously.
///
/// In most cases you do not need to implement this trait manually: the
/// `intrusive_adapter!` macro will generate the necessary implementation for a
/// given type and its link field. However it is possible to implement it
/// manually if the intrusive link is not a direct field of the object type.
///
/// It is also possible to create stateful adapters. This allows links and
/// containers to be separated and avoids the need for objects to be modified to
/// contain a link.
///
/// # Safety
///
/// It must be possible to get back a reference to the container by passing a
/// pointer returned by `get_link` to `get_container`.
pub unsafe trait Adapter {
/// Collection-specific link type which allows an object to be inserted in
/// an intrusive collection.
type Link;
/// Object type which is inserted in an intrusive collection.
type Value: ?Sized;
/// Pointer type which owns an instance of a value.
type Pointer: IntrusivePointer<Self::Value>;
/// Gets a reference to an object from a reference to a link in that object.
unsafe fn get_value(&self, link: *const Self::Link) -> *const Self::Value;
/// Gets a reference to the link for the given object.
unsafe fn get_link(&self, value: *const Self::Value) -> *const Self::Link;
}
/// Macro to get the offset of a struct field in bytes from the address of the
/// struct.
#[macro_export]
macro_rules! offset_of {
($container:path, $field:ident) => {{
// Make sure the field actually exists. This line ensures that a
// compile-time error is generated if $field is accessed through a
// Deref impl.
#[cfg_attr(feature = "cargo-clippy", allow(unneeded_field_pattern))]
let $container { $field: _, .. };
// Create an instance of the container and calculate the offset to its
// field. Although we are creating references to uninitialized data this
// is fine since we are not dereferencing them.
#[allow(unused_unsafe)]
let val: $container = unsafe { $crate::__core::mem::uninitialized() };
let result = &val.$field as *const _ as usize - &val as *const _ as usize;
#[cfg_attr(feature = "cargo-clippy", allow(forget_copy))]
$crate::__core::mem::forget(val);
result as isize
}};
}
/// Unsafe macro to get a raw pointer to an outer object from a pointer to one
/// of its fields.
///
/// # Examples
///
/// ```
/// # #[macro_use] extern crate intrusive_collections;
/// # fn main() {
/// struct S { x: u32, y: u32 };
/// let container = S { x: 1, y: 2 };
/// let field = &container.x;
/// let container2: *const S = unsafe { container_of!(field, S, x) };
/// assert_eq!(&container as *const S, container2);
/// # }
/// ```
///
/// # Safety
///
/// This is unsafe because it assumes that the given expression is a valid
/// pointer to the specified field of some container type.
#[macro_export(local_inner_macros)]
macro_rules! container_of {
($ptr:expr, $container:path, $field:ident) => {
#[cfg_attr(feature = "cargo-clippy", allow(cast_ptr_alignment))]
{
($ptr as *const _ as *const u8).offset(-offset_of!($container, $field))
as *mut $container
}
};
}
// Note that we define the macro twice here. The nightly version of the macro
// defines the new() constructor for adapters as a const fn, while the normal
// version defines it as a normal function. Unfortunately, this is necessary
// because #[cfg] in a macro are evaluated in crates using the macro rather
// than the crate which defines the macro.
/// Macro to generate an implementation of `Adapter` for a given set of types.
/// In particular this will automatically generate implementations of the
/// `get_value` and `get_link` methods for a given named field in a struct.
///
/// The basic syntax to create an adapter is:
///
/// ```rust,ignore
/// intrusive_adapter!(Adapter = Pointer: Value { link_field: LinkType });
/// ```
///
/// # Generics
///
/// This macro supports generic arguments:
///
/// ```rust,ignore
/// intrusive_adapter!(
/// Adapter<'lifetime, Type, Type2: ?Sized> =
/// Pointer: Value {
/// link_field: LinkType
/// }
/// where
/// Type: Copy,
/// Type2: 'lifetime
/// );
/// ```
///
/// Note that due to macro parsing limitations, only `?Trait` style bounds are
/// allowed in the generic argument list. In most cases this is only needed for
/// `?Sized`. Other bounds can be specified in the `where` clause at the end
/// the macro.
///
/// # Examples
///
/// ```
/// #[macro_use]
/// extern crate intrusive_collections;
/// use intrusive_collections::{LinkedListLink, RBTreeLink};
///
/// pub struct Test {
/// link: LinkedListLink,
/// link2: RBTreeLink,
/// }
/// intrusive_adapter!(MyAdapter = Box<Test>: Test { link: LinkedListLink });
/// intrusive_adapter!(pub MyAdapter2 = Box<Test>: Test { link2: RBTreeLink });
///
/// pub struct Test2<T: ?Sized>
/// where T: Clone
/// {
/// link: LinkedListLink,
/// val: T,
/// }
/// intrusive_adapter!(MyAdapter3<'a, T: ?Sized> = &'a Test2<T>: Test2<T> { link: LinkedListLink } where T: Clone + 'a);
/// # fn main() {}
/// ```
#[cfg(feature = "nightly")]
#[macro_export(local_inner_macros)]
#[allow_internal_unstable]
macro_rules! intrusive_adapter {
(@impl
($($privacy:tt)*) $name:ident ($($args:tt $(: ?$bound:tt)*),*)
= $pointer:ty: $value:path { $field:ident: $link:ty } $($where_:tt)*
) => {
$($privacy)* struct $name<$($args),*>($crate::__core::marker::PhantomData<$pointer>) $($where_)*;
unsafe impl<$($args $(: ?$bound)*),*> Send for $name<$($args),*> $($where_)* {}
unsafe impl<$($args $(: ?$bound)*),*> Sync for $name<$($args),*> $($where_)* {}
impl<$($args $(: ?$bound)*),*> Copy for $name<$($args),*> $($where_)* {}
impl<$($args $(: ?$bound)*),*> Clone for $name<$($args),*> $($where_)* {
fn clone(&self) -> Self {
*self
}
}
impl<$($args $(: ?$bound)*),*> Default for $name<$($args),*> $($where_)* {
fn default() -> Self {
Self::new()
}
}
#[allow(dead_code)]
impl<$($args $(: ?$bound)*),*> $name<$($args),*> $($where_)* {
pub const fn new() -> Self {
$name($crate::__core::marker::PhantomData)
}
}
#[allow(dead_code, unsafe_code)]
unsafe impl<$($args $(: ?$bound)*),*> $crate::Adapter for $name<$($args),*> $($where_)* {
type Link = $link;
type Value = $value;
type Pointer = $pointer;
#[inline]
unsafe fn get_value(&self, link: *const $link) -> *const $value {
container_of!(link, $value, $field)
}
#[inline]
unsafe fn get_link(&self, value: *const $value) -> *const $link {
&(*value).$field
}
}
};
(@find_generic
($($privacy:tt)*) $name:tt ($($prev:tt)*) > $($rest:tt)*
) => {
intrusive_adapter!(@impl
($($privacy)*) $name ($($prev)*) $($rest)*
);
};
(@find_generic
($($privacy:tt)*) $name:tt ($($prev:tt)*) $cur:tt $($rest:tt)*
) => {
intrusive_adapter!(@find_generic
($($privacy)*) $name ($($prev)* $cur) $($rest)*
);
};
(@find_if_generic
($($privacy:tt)*) $name:tt < $($rest:tt)*
) => {
intrusive_adapter!(@find_generic
($($privacy)*) $name () $($rest)*
);
};
(@find_if_generic
($($privacy:tt)*) $name:tt $($rest:tt)*
) => {
intrusive_adapter!(@impl
($($privacy)*) $name () $($rest)*
);
};
(pub $name:tt $($rest:tt)*) => {
intrusive_adapter!(@find_if_generic
(pub) $name $($rest)*
);
};
($name:tt $($rest:tt)*) => {
intrusive_adapter!(@find_if_generic
() $name $($rest)*
);
};
}
/// Macro to generate an implementation of `Adapter` for a given set of types.
/// In particular this will automatically generate implementations of the
/// `get_value` and `get_link` methods for a given named field in a struct.
///
/// The basic syntax to create an adapter is:
///
/// ```rust,ignore
/// intrusive_adapter!(Adapter = Pointer: Value { link_field: LinkType });
/// ```
///
/// # Generics
///
/// This macro supports generic arguments:
///
/// ```rust,ignore
/// intrusive_adapter!(Adapter<'lifetime, Type, Type2: ?Sized> = Pointer: Value { link_field: LinkType } where Type: Copy, Type2: 'lifetiem);
/// ```
///
/// Note that due to macro parsing limitations, only `?Trait` style bounds are
/// allowed in the generic argument list. In most cases this is only needed for
/// `?Sized`. Other bounds can be specified in the `where` clause at the end
/// the macro.
///
/// # Examples
///
/// ```
/// #[macro_use]
/// extern crate intrusive_collections;
/// use intrusive_collections::{LinkedListLink, RBTreeLink};
///
/// pub struct Test {
/// link: LinkedListLink,
/// link2: RBTreeLink,
/// }
/// intrusive_adapter!(MyAdapter = Box<Test>: Test { link: LinkedListLink });
/// intrusive_adapter!(pub MyAdapter2 = Box<Test>: Test { link2: RBTreeLink });
///
/// pub struct Test2<T: ?Sized>
/// where T: Clone
/// {
/// link: LinkedListLink,
/// val: T,
/// }
/// intrusive_adapter!(MyAdapter3<'a, T: ?Sized> = &'a Test2<T>: Test2<T> { link: LinkedListLink } where T: Clone + 'a);
/// # fn main() {}
/// ```
#[cfg(not(feature = "nightly"))]
#[macro_export(local_inner_macros)]
macro_rules! intrusive_adapter {
(@impl
($($privacy:tt)*) $name:ident ($($args:tt $(: ?$bound:tt)*),*)
= $pointer:ty: $value:path { $field:ident: $link:ty } $($where_:tt)*
) => {
$($privacy)* struct $name<$($args),*>($crate::__core::marker::PhantomData<$pointer>) $($where_)*;
unsafe impl<$($args $(: ?$bound)*),*> Send for $name<$($args),*> $($where_)* {}
unsafe impl<$($args $(: ?$bound)*),*> Sync for $name<$($args),*> $($where_)* {}
impl<$($args $(: ?$bound)*),*> Copy for $name<$($args),*> $($where_)* {}
impl<$($args $(: ?$bound)*),*> Clone for $name<$($args),*> $($where_)* {
fn clone(&self) -> Self {
*self
}
}
impl<$($args $(: ?$bound)*),*> Default for $name<$($args),*> $($where_)* {
fn default() -> Self {
Self::new()
}
}
#[allow(dead_code)]
impl<$($args $(: ?$bound)*),*> $name<$($args),*> $($where_)* {
pub fn new() -> Self {
$name($crate::__core::marker::PhantomData)
}
}
#[allow(dead_code, unsafe_code)]
unsafe impl<$($args $(: ?$bound)*),*> $crate::Adapter for $name<$($args),*> $($where_)* {
type Link = $link;
type Value = $value;
type Pointer = $pointer;
#[inline]
unsafe fn get_value(&self, link: *const $link) -> *const $value {
container_of!(link, $value, $field)
}
#[inline]
unsafe fn get_link(&self, value: *const $value) -> *const $link {
&(*value).$field
}
}
};
(@find_generic
($($privacy:tt)*) $name:tt ($($prev:tt)*) > $($rest:tt)*
) => {
intrusive_adapter!(@impl
($($privacy)*) $name ($($prev)*) $($rest)*
);
};
(@find_generic
($($privacy:tt)*) $name:tt ($($prev:tt)*) $cur:tt $($rest:tt)*
) => {
intrusive_adapter!(@find_generic
($($privacy)*) $name ($($prev)* $cur) $($rest)*
);
};
(@find_if_generic
($($privacy:tt)*) $name:tt < $($rest:tt)*
) => {
intrusive_adapter!(@find_generic
($($privacy)*) $name () $($rest)*
);
};
(@find_if_generic
($($privacy:tt)*) $name:tt $($rest:tt)*
) => {
intrusive_adapter!(@impl
($($privacy)*) $name () $($rest)*
);
};
(pub $name:tt $($rest:tt)*) => {
intrusive_adapter!(@find_if_generic
(pub) $name $($rest)*
);
};
($name:tt $($rest:tt)*) => {
intrusive_adapter!(@find_if_generic
() $name $($rest)*
);
};
}