1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432
use core::cmp; use core::convert::TryFrom; use core::fmt; use core::marker::PhantomData; use core::ptr::NonNull; use typenum::{IsGreaterOrEqual, True, Unsigned}; use crate::internal::Internal; use crate::pointer::{ self, InvalidNullError, Marked::{self, Null, Value}, MarkedNonNull, MarkedPtr, NonNullable, }; //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Copy & Clone //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N> Clone for MarkedNonNull<T, N> { #[inline] fn clone(&self) -> Self { Self::from(self.inner) } } impl<T, N> Copy for MarkedNonNull<T, N> {} //////////////////////////////////////////////////////////////////////////////////////////////////// // impl inherent //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N> MarkedNonNull<T, N> { /// Cast to a pointer of another type. #[inline] pub const fn cast<U>(self) -> MarkedNonNull<U, N> { MarkedNonNull { inner: self.inner.cast(), _marker: PhantomData } } /// Creates a new `MarkedNonNull` that is dangling, but well-aligned. /// /// This is useful for initializing types which lazily allocate, like /// `Vec::new` does. /// /// Note that the pointer value may potentially represent a valid pointer to /// a `T`, which means this must not be used as a "not yet initialized" /// sentinel value. Types that lazily allocate must track initialization by /// some other means. #[inline] pub const fn dangling() -> Self { Self { inner: NonNull::dangling(), _marker: PhantomData } } } impl<T, N: Unsigned> MarkedNonNull<T, N> { /// The number of available mark bits for this type. pub const MARK_BITS: usize = N::USIZE; /// The bitmask for the lower markable bits. pub const MARK_MASK: usize = pointer::mark_mask::<T>(Self::MARK_BITS); /// The bitmask for the (higher) pointer bits. pub const POINTER_MASK: usize = !Self::MARK_MASK; /// Returns the inner pointer *as is*, meaning potential tags are not /// stripped. #[inline] pub fn into_non_null(self) -> NonNull<T> { self.inner } /// Converts a marked non-null pointer with `M` potential mark bits to the /// **same** marked pointer with `N` potential mark bits, requires that /// `N >= M`. #[inline] pub fn convert<M: Unsigned>(other: MarkedNonNull<T, M>) -> Self where N: IsGreaterOrEqual<M, Output = True>, { Self::from(other.inner) } /// Creates a new `MarkedNonNull` from a marked pointer without checking /// for `null`. /// /// # Safety /// /// `ptr` may be marked, but must be be neither an unmarked nor a marked /// null pointer. #[inline] pub unsafe fn new_unchecked(ptr: MarkedPtr<T, N>) -> Self { Self::from(NonNull::new_unchecked(ptr.inner)) } /// Creates a new `MarkedNonNull` wrapped in a [`Marked`] if `ptr` is /// non-null. pub fn new(ptr: MarkedPtr<T, N>) -> Marked<Self> { match ptr.decompose() { (raw, _) if !raw.is_null() => unsafe { Value(Self::new_unchecked(ptr)) }, (_, tag) => Null(tag), } } /// Clears the tag of `self` and returns the same but untagged pointer. #[inline] pub fn clear_tag(self) -> Self { Self::from(self.decompose_non_null()) } /// Clears the tag of `self` and replaces it with `tag`. #[inline] pub fn with_tag(self, tag: usize) -> Self { Self::compose(self.decompose_non_null(), tag) } /// Converts the pointer to the equivalent [`MarkedPtr`]. #[inline] pub fn into_marked_ptr(self) -> MarkedPtr<T, N> { MarkedPtr::new(self.inner.as_ptr()) } /// Composes a new marked non-null pointer from a non-null pointer and a tag /// value. #[inline] pub fn compose(ptr: NonNull<T>, tag: usize) -> Self { debug_assert_eq!(0, ptr.as_ptr() as usize & Self::MARK_MASK, "`ptr` is not well aligned"); unsafe { Self::from(NonNull::new_unchecked(pointer::compose::<_, N>(ptr.as_ptr(), tag))) } } /// Decomposes the marked pointer, returning the separated raw /// [`NonNull`] pointer and its tag. #[inline] pub fn decompose(self) -> (NonNull<T>, usize) { let (ptr, tag) = pointer::decompose(self.inner.as_ptr() as usize, Self::MARK_BITS); (unsafe { NonNull::new_unchecked(ptr) }, tag) } /// Decomposes the marked pointer, returning only the separated raw pointer. #[inline] pub fn decompose_ptr(self) -> *mut T { pointer::decompose_ptr(self.inner.as_ptr() as usize, Self::MARK_BITS) } /// Decomposes the marked pointer, returning only the separated raw /// [`NonNull`] pointer. #[inline] pub fn decompose_non_null(self) -> NonNull<T> { unsafe { NonNull::new_unchecked(pointer::decompose_ptr( self.inner.as_ptr() as usize, Self::MARK_BITS, )) } } /// Decomposes the marked pointer, returning only the separated tag. #[inline] pub fn decompose_tag(self) -> usize { pointer::decompose_tag::<T>(self.inner.as_ptr() as usize, Self::MARK_BITS) } /// Decomposes the marked pointer, dereferences the the raw pointer and /// returns both the reference and the separated tag. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use e.g. `&*my_ptr.decompose_ptr()`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer. #[inline] pub unsafe fn decompose_ref(&self) -> (&T, usize) { let (ptr, tag) = self.decompose(); (&*ptr.as_ptr(), tag) } /// Decomposes the marked pointer, dereferences the the raw pointer and /// returns both the reference and the separated tag. The returned reference /// is not bound to the lifetime of the `MarkedNonNull`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer, nor can it ensure that the lifetime `'a` returned is indeed a /// valid lifetime for the contained data. #[inline] pub unsafe fn decompose_ref_unbounded<'a>(self) -> (&'a T, usize) { let (ptr, tag) = self.decompose(); (&*ptr.as_ptr(), tag) } /// Decomposes the marked pointer, mutably dereferences the the raw pointer /// and returns both the mutable reference and the separated tag. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use e.g. `&mut *my_ptr.decompose_ptr()`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer. #[inline] pub unsafe fn decompose_mut(&mut self) -> (&mut T, usize) { let (ptr, tag) = self.decompose(); (&mut *ptr.as_ptr(), tag) } /// Decomposes the marked pointer, mutably dereferences the the raw pointer /// and returns both the mutable reference and the separated tag. The /// returned reference is not bound to the lifetime of the `MarkedNonNull`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer, nor can it ensure that the lifetime `'a` returned is indeed a /// valid lifetime for the contained data. #[inline] pub unsafe fn decompose_mut_unbounded<'a>(&mut self) -> (&'a mut T, usize) { let (ptr, tag) = self.decompose(); (&mut *ptr.as_ptr(), tag) } /// Decomposes the marked pointer, returning only the de-referenced raw /// pointer. /// /// The resulting lifetime is bound to self so this behaves "as if" it were /// actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use e.g. `&*my_ptr.decompose_ptr()` /// or [`as_ref_unbounded`][MarkedNonNull::as_ref_unbounded]. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer. #[inline] pub unsafe fn as_ref(&self) -> &T { &*self.decompose_non_null().as_ptr() } /// Decomposes the marked pointer, returning only the de-referenced raw /// pointer, which is not bound to the lifetime of the `MarkedNonNull`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer, nor can it ensure that the lifetime `'a` returned is indeed a /// valid lifetime for the contained data. #[inline] pub unsafe fn as_ref_unbounded<'a>(self) -> &'a T { &*self.decompose_non_null().as_ptr() } /// Decomposes the marked pointer, returning only the mutably de-referenced /// raw pointer. /// /// The resulting lifetime is bound to self so this behaves "as if" /// it were actually an instance of T that is getting borrowed. If a longer /// (unbound) lifetime is needed, use e.g. `&mut *my_ptr.decompose_ptr()` /// or [`as_mut_unbounded`][MarkedNonNull::as_ref_unbounded]. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer. #[inline] pub unsafe fn as_mut(&mut self) -> &mut T { &mut *self.decompose_non_null().as_ptr() } /// Decomposes the marked pointer, returning only the mutably de-referenced /// raw pointer, which is not bound to the lifetime of the `MarkedNonNull`. /// /// # Safety /// /// This is unsafe because it cannot verify the validity of the returned /// pointer, nor can it ensure that the lifetime `'a` returned is indeed a /// valid lifetime for the contained data. #[inline] pub unsafe fn as_mut_unbounded<'a>(self) -> &'a mut T { &mut *self.decompose_non_null().as_ptr() } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Debug & Pointer (fmt) //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N: Unsigned> fmt::Debug for MarkedNonNull<T, N> { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { let (ptr, tag) = self.decompose(); f.debug_struct("MarkedNonNull").field("ptr", &ptr).field("tag", &tag).finish() } } impl<T, N: Unsigned> fmt::Pointer for MarkedNonNull<T, N> { #[inline] fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { fmt::Pointer::fmt(&self.decompose_non_null(), f) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl From & TryFrom //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N> From<NonNull<T>> for MarkedNonNull<T, N> { #[inline] fn from(ptr: NonNull<T>) -> Self { Self { inner: ptr, _marker: PhantomData } } } impl<'a, T, N: Unsigned> From<&'a T> for MarkedNonNull<T, N> { #[inline] fn from(reference: &'a T) -> Self { Self::from(NonNull::from(reference)) } } impl<'a, T, N: Unsigned> From<&'a mut T> for MarkedNonNull<T, N> { #[inline] fn from(reference: &'a mut T) -> Self { Self::from(NonNull::from(reference)) } } impl<T, N: Unsigned> TryFrom<MarkedPtr<T, N>> for MarkedNonNull<T, N> { type Error = InvalidNullError; #[inline] fn try_from(ptr: MarkedPtr<T, N>) -> Result<Self, Self::Error> { match ptr.decompose() { (raw, _) if raw.is_null() => Err(InvalidNullError), _ => unsafe { Ok(MarkedNonNull::new_unchecked(ptr)) }, } } } //////////////////////////////////////////////////////////////////////////////////////////////////// // impl Eq, Ord, PartialEq, PartialOrd //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N> PartialEq for MarkedNonNull<T, N> { #[inline] fn eq(&self, other: &Self) -> bool { self.inner == other.inner } } impl<T, N> PartialOrd for MarkedNonNull<T, N> { #[inline] fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { self.inner.partial_cmp(&other.inner) } } impl<T, N> Eq for MarkedNonNull<T, N> {} impl<T, N> Ord for MarkedNonNull<T, N> { #[inline] fn cmp(&self, other: &Self) -> cmp::Ordering { self.inner.cmp(&other.inner) } } impl<T, N> PartialEq<MarkedPtr<T, N>> for MarkedNonNull<T, N> { #[inline] fn eq(&self, other: &MarkedPtr<T, N>) -> bool { self.inner.as_ptr() == other.inner } } impl<T, N> PartialOrd<MarkedPtr<T, N>> for MarkedNonNull<T, N> { #[inline] fn partial_cmp(&self, other: &MarkedPtr<T, N>) -> Option<cmp::Ordering> { self.inner.as_ptr().partial_cmp(&other.inner) } } //////////////////////////////////////////////////////////////////////////////////////////////////// // NonNullable //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N: Unsigned> NonNullable for MarkedNonNull<T, N> { type Item = T; type MarkBits = N; #[inline] fn into_marked_non_null(self) -> MarkedNonNull<Self::Item, Self::MarkBits> { self } } //////////////////////////////////////////////////////////////////////////////////////////////////// // Internal //////////////////////////////////////////////////////////////////////////////////////////////////// impl<T, N: Unsigned> Internal for MarkedNonNull<T, N> {} #[cfg(test)] mod tests { use std::ptr; use typenum::U2; use crate::align::Aligned4; type MarkedPtr<T> = crate::pointer::MarkedPtr<T, U2>; type MarkedNonNull<T> = crate::pointer::MarkedNonNull<T, U2>; #[test] fn new() { let reference = &mut Aligned4(1); let unmarked = MarkedPtr::new(reference); let marked = MarkedNonNull::new(unmarked); assert_eq!(unsafe { marked.unwrap_value().decompose_ref() }, (&Aligned4(1), 0)); let marked = MarkedNonNull::new(MarkedPtr::compose(reference, 0b11)); assert_eq!(unsafe { marked.unwrap_value().decompose_ref() }, (&Aligned4(1), 0b11)); let null: *mut Aligned4<i32> = ptr::null_mut(); let marked = MarkedNonNull::new(MarkedPtr::compose(null, 0b11)); assert!(marked.is_null()); assert_eq!(marked.unwrap_null(), 0b11); let marked = MarkedNonNull::new(MarkedPtr::compose(null, 0)); assert!(marked.is_null()); } }