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Move placement new operators to module.

This commit is contained in:
Clar Charr 2017-06-07 22:10:21 -04:00
parent d460aca720
commit f774cddcf2
2 changed files with 130 additions and 119 deletions
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123
src/libcore/ops/mod.rs
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@ -150,17 +150,16 @@
mod arith;
mod bit;
mod function;
mod place;
mod range;
#[stable(feature = "rust1", since = "1.0.0")]
pub use self::arith::{Add, Sub, Mul, Div, Rem, Neg};
#[stable(feature = "op_assign_traits", since = "1.8.0")]
pub use self::arith::{AddAssign, SubAssign, MulAssign, DivAssign, RemAssign};
#[stable(feature = "rust1", since = "1.0.0")]
pub use self::bit::{Not, BitAnd, BitOr, BitXor, Shl, Shr};
#[stable(feature = "op_assign_traits", since = "1.8.0")]
pub use self::bit::{BitAndAssign, BitOrAssign, BitXorAssign, ShlAssign, ShrAssign};
@ -173,6 +172,9 @@ pub use self::range::{Range, RangeFrom, RangeFull, RangeTo};
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
pub use self::range::{RangeInclusive, RangeToInclusive};
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub use self::place::{Place, Placer, InPlace, Boxed, BoxPlace};
use marker::Unsize;
/// The `Drop` trait is used to run some code when a value goes out of scope.
@ -592,123 +594,6 @@ impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
#[unstable(feature = "coerce_unsized", issue = "27732")]
impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
/// Both `PLACE <- EXPR` and `box EXPR` desugar into expressions
/// that allocate an intermediate "place" that holds uninitialized
/// state. The desugaring evaluates EXPR, and writes the result at
/// the address returned by the `pointer` method of this trait.
///
/// A `Place` can be thought of as a special representation for a
/// hypothetical `&uninit` reference (which Rust cannot currently
/// express directly). That is, it represents a pointer to
/// uninitialized storage.
///
/// The client is responsible for two steps: First, initializing the
/// payload (it can access its address via `pointer`). Second,
/// converting the agent to an instance of the owning pointer, via the
/// appropriate `finalize` method (see the `InPlace`.
///
/// If evaluating EXPR fails, then it is up to the destructor for the
/// implementation of Place to clean up any intermediate state
/// (e.g. deallocate box storage, pop a stack, etc).
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Place<Data: ?Sized> {
/// Returns the address where the input value will be written.
/// Note that the data at this address is generally uninitialized,
/// and thus one should use `ptr::write` for initializing it.
fn pointer(&mut self) -> *mut Data;
}
/// Interface to implementations of `PLACE <- EXPR`.
///
/// `PLACE <- EXPR` effectively desugars into:
///
/// ```rust,ignore
/// let p = PLACE;
/// let mut place = Placer::make_place(p);
/// let raw_place = Place::pointer(&mut place);
/// let value = EXPR;
/// unsafe {
/// std::ptr::write(raw_place, value);
/// InPlace::finalize(place)
/// }
/// ```
///
/// The type of `PLACE <- EXPR` is derived from the type of `PLACE`;
/// if the type of `PLACE` is `P`, then the final type of the whole
/// expression is `P::Place::Owner` (see the `InPlace` and `Boxed`
/// traits).
///
/// Values for types implementing this trait usually are transient
/// intermediate values (e.g. the return value of `Vec::emplace_back`)
/// or `Copy`, since the `make_place` method takes `self` by value.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Placer<Data: ?Sized> {
/// `Place` is the intermedate agent guarding the
/// uninitialized state for `Data`.
type Place: InPlace<Data>;
/// Creates a fresh place from `self`.
fn make_place(self) -> Self::Place;
}
/// Specialization of `Place` trait supporting `PLACE <- EXPR`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait InPlace<Data: ?Sized>: Place<Data> {
/// `Owner` is the type of the end value of `PLACE <- EXPR`
///
/// Note that when `PLACE <- EXPR` is solely used for
/// side-effecting an existing data-structure,
/// e.g. `Vec::emplace_back`, then `Owner` need not carry any
/// information at all (e.g. it can be the unit type `()` in that
/// case).
type Owner;
/// Converts self into the final value, shifting
/// deallocation/cleanup responsibilities (if any remain), over to
/// the returned instance of `Owner` and forgetting self.
unsafe fn finalize(self) -> Self::Owner;
}
/// Core trait for the `box EXPR` form.
///
/// `box EXPR` effectively desugars into:
///
/// ```rust,ignore
/// let mut place = BoxPlace::make_place();
/// let raw_place = Place::pointer(&mut place);
/// let value = EXPR;
/// unsafe {
/// ::std::ptr::write(raw_place, value);
/// Boxed::finalize(place)
/// }
/// ```
///
/// The type of `box EXPR` is supplied from its surrounding
/// context; in the above expansion, the result type `T` is used
/// to determine which implementation of `Boxed` to use, and that
/// `<T as Boxed>` in turn dictates determines which
/// implementation of `BoxPlace` to use, namely:
/// `<<T as Boxed>::Place as BoxPlace>`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Boxed {
/// The kind of data that is stored in this kind of box.
type Data; /* (`Data` unused b/c cannot yet express below bound.) */
/// The place that will negotiate the storage of the data.
type Place: BoxPlace<Self::Data>;
/// Converts filled place into final owning value, shifting
/// deallocation/cleanup responsibilities (if any remain), over to
/// returned instance of `Self` and forgetting `filled`.
unsafe fn finalize(filled: Self::Place) -> Self;
}
/// Specialization of `Place` trait supporting `box EXPR`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait BoxPlace<Data: ?Sized> : Place<Data> {
/// Creates a globally fresh place.
fn make_place() -> Self;
}
/// This trait has been superseded by the `Try` trait, but must remain
/// here as `?` is still lowered to it in stage0 .
#[cfg(stage0)]

126
src/libcore/ops/place.rs Normal file
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@ -0,0 +1,126 @@
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.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.
/// Both `PLACE <- EXPR` and `box EXPR` desugar into expressions
/// that allocate an intermediate "place" that holds uninitialized
/// state. The desugaring evaluates EXPR, and writes the result at
/// the address returned by the `pointer` method of this trait.
///
/// A `Place` can be thought of as a special representation for a
/// hypothetical `&uninit` reference (which Rust cannot currently
/// express directly). That is, it represents a pointer to
/// uninitialized storage.
///
/// The client is responsible for two steps: First, initializing the
/// payload (it can access its address via `pointer`). Second,
/// converting the agent to an instance of the owning pointer, via the
/// appropriate `finalize` method (see the `InPlace`.
///
/// If evaluating EXPR fails, then it is up to the destructor for the
/// implementation of Place to clean up any intermediate state
/// (e.g. deallocate box storage, pop a stack, etc).
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Place<Data: ?Sized> {
/// Returns the address where the input value will be written.
/// Note that the data at this address is generally uninitialized,
/// and thus one should use `ptr::write` for initializing it.
fn pointer(&mut self) -> *mut Data;
}
/// Interface to implementations of `PLACE <- EXPR`.
///
/// `PLACE <- EXPR` effectively desugars into:
///
/// ```rust,ignore
/// let p = PLACE;
/// let mut place = Placer::make_place(p);
/// let raw_place = Place::pointer(&mut place);
/// let value = EXPR;
/// unsafe {
/// std::ptr::write(raw_place, value);
/// InPlace::finalize(place)
/// }
/// ```
///
/// The type of `PLACE <- EXPR` is derived from the type of `PLACE`;
/// if the type of `PLACE` is `P`, then the final type of the whole
/// expression is `P::Place::Owner` (see the `InPlace` and `Boxed`
/// traits).
///
/// Values for types implementing this trait usually are transient
/// intermediate values (e.g. the return value of `Vec::emplace_back`)
/// or `Copy`, since the `make_place` method takes `self` by value.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Placer<Data: ?Sized> {
/// `Place` is the intermedate agent guarding the
/// uninitialized state for `Data`.
type Place: InPlace<Data>;
/// Creates a fresh place from `self`.
fn make_place(self) -> Self::Place;
}
/// Specialization of `Place` trait supporting `PLACE <- EXPR`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait InPlace<Data: ?Sized>: Place<Data> {
/// `Owner` is the type of the end value of `PLACE <- EXPR`
///
/// Note that when `PLACE <- EXPR` is solely used for
/// side-effecting an existing data-structure,
/// e.g. `Vec::emplace_back`, then `Owner` need not carry any
/// information at all (e.g. it can be the unit type `()` in that
/// case).
type Owner;
/// Converts self into the final value, shifting
/// deallocation/cleanup responsibilities (if any remain), over to
/// the returned instance of `Owner` and forgetting self.
unsafe fn finalize(self) -> Self::Owner;
}
/// Core trait for the `box EXPR` form.
///
/// `box EXPR` effectively desugars into:
///
/// ```rust,ignore
/// let mut place = BoxPlace::make_place();
/// let raw_place = Place::pointer(&mut place);
/// let value = EXPR;
/// unsafe {
/// ::std::ptr::write(raw_place, value);
/// Boxed::finalize(place)
/// }
/// ```
///
/// The type of `box EXPR` is supplied from its surrounding
/// context; in the above expansion, the result type `T` is used
/// to determine which implementation of `Boxed` to use, and that
/// `<T as Boxed>` in turn dictates determines which
/// implementation of `BoxPlace` to use, namely:
/// `<<T as Boxed>::Place as BoxPlace>`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait Boxed {
/// The kind of data that is stored in this kind of box.
type Data; /* (`Data` unused b/c cannot yet express below bound.) */
/// The place that will negotiate the storage of the data.
type Place: BoxPlace<Self::Data>;
/// Converts filled place into final owning value, shifting
/// deallocation/cleanup responsibilities (if any remain), over to
/// returned instance of `Self` and forgetting `filled`.
unsafe fn finalize(filled: Self::Place) -> Self;
}
/// Specialization of `Place` trait supporting `box EXPR`.
#[unstable(feature = "placement_new_protocol", issue = "27779")]
pub trait BoxPlace<Data: ?Sized> : Place<Data> {
/// Creates a globally fresh place.
fn make_place() -> Self;
}