/
ptr.rs
141 lines (119 loc) · 3.63 KB
/
ptr.rs
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// HACK(eddyb) this is a copy of `syntax::ptr`, minus the mutation (the HIR is
// frozen anyway). The only reason for doing this instead of replacing `P<T>`
// with `Box<T>` in HIR, is that `&Box<[T]>` doesn't implement `IntoIterator`.
use std::fmt::{self, Display, Debug};
use std::iter::FromIterator;
use std::ops::Deref;
use std::{slice, vec};
use serialize::{Encodable, Decodable, Encoder, Decoder};
use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult,
HashStable};
/// An owned smart pointer.
#[derive(Hash, PartialEq, Eq)]
pub struct P<T: ?Sized> {
ptr: Box<T>
}
/// Construct a `P<T>` from a `T` value.
#[allow(non_snake_case)]
pub fn P<T: 'static>(value: T) -> P<T> {
P {
ptr: box value
}
}
impl<T: 'static> P<T> {
// HACK(eddyb) used by HIR lowering in a few places still.
// NOTE: do not make this more public than `pub(super)`.
pub(super) fn into_inner(self) -> T {
*self.ptr
}
}
impl<T: ?Sized> Deref for P<T> {
type Target = T;
fn deref(&self) -> &T {
&self.ptr
}
}
impl<T: ?Sized + Debug> Debug for P<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
Debug::fmt(&self.ptr, f)
}
}
impl<T: Display> Display for P<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
Display::fmt(&**self, f)
}
}
impl<T: 'static + Decodable> Decodable for P<T> {
fn decode<D: Decoder>(d: &mut D) -> Result<P<T>, D::Error> {
Decodable::decode(d).map(P)
}
}
impl<T: Encodable> Encodable for P<T> {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
(**self).encode(s)
}
}
impl<T> P<[T]> {
pub const fn new() -> P<[T]> {
// HACK(eddyb) bypass the lack of a `const fn` to create an empty `Box<[T]>`
// (as trait methods, `default` in this case, can't be `const fn` yet).
P {
ptr: unsafe {
use std::ptr::NonNull;
std::mem::transmute(NonNull::<[T; 0]>::dangling() as NonNull<[T]>)
},
}
}
#[inline(never)]
pub fn from_vec(v: Vec<T>) -> P<[T]> {
P { ptr: v.into_boxed_slice() }
}
// HACK(eddyb) used by HIR lowering in a few places still.
// NOTE: do not make this more public than `pub(super)`,
// and do not make this into an `IntoIterator` impl.
pub(super) fn into_iter(self) -> vec::IntoIter<T> {
self.ptr.into_vec().into_iter()
}
}
impl<T> Default for P<[T]> {
/// Creates an empty `P<[T]>`.
fn default() -> P<[T]> {
P::new()
}
}
impl<T> From<Vec<T>> for P<[T]> {
fn from(v: Vec<T>) -> Self {
P::from_vec(v)
}
}
impl<T> FromIterator<T> for P<[T]> {
fn from_iter<I: IntoIterator<Item=T>>(iter: I) -> P<[T]> {
P::from_vec(iter.into_iter().collect())
}
}
impl<'a, T> IntoIterator for &'a P<[T]> {
type Item = &'a T;
type IntoIter = slice::Iter<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.ptr.into_iter()
}
}
impl<T: Encodable> Encodable for P<[T]> {
fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
Encodable::encode(&**self, s)
}
}
impl<T: Decodable> Decodable for P<[T]> {
fn decode<D: Decoder>(d: &mut D) -> Result<P<[T]>, D::Error> {
Ok(P::from_vec(Decodable::decode(d)?))
}
}
impl<CTX, T> HashStable<CTX> for P<T>
where T: ?Sized + HashStable<CTX>
{
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut CTX,
hasher: &mut StableHasher<W>) {
(**self).hash_stable(hcx, hasher);
}
}