Struct std::ptr::Unique
[−]
[src]
pub struct Unique<T> where T: ?Sized {
// some fields omitted
}A wrapper around a raw *mut T that indicates that the possessor
of this wrapper owns the referent. This in turn implies that the
Unique<T> is Send/Sync if T is Send/Sync, unlike a raw
*mut T (which conveys no particular ownership semantics). It
also implies that the referent of the pointer should not be
modified without a unique path to the Unique reference. Useful
for building abstractions like Vec<T> or Box<T>, which
internally use raw pointers to manage the memory that they own.
Methods
impl<T> Unique<T> where T: ?Sized
unsafe fn new(ptr: *mut T) -> Unique<T>
Creates a new Unique.
unsafe fn get(&self) -> &T
Dereferences the content.
unsafe fn get_mut(&mut self) -> &mut T
Mutably dereferences the content.
Methods from Deref<Target=*mut T>
fn is_null(self) -> bool
Returns true if the pointer is null.
unsafe fn as_ref(&self) -> Option<&'a T>
: Option is not clearly the right return type, and we may want to tie the return lifetime to a borrow of the raw pointer
Returns None if the pointer is null, or else returns a reference to
the value wrapped in Some.
Safety
While this method and its mutable counterpart are useful for null-safety, it is important to note that this is still an unsafe operation because the returned value could be pointing to invalid memory.
unsafe fn offset(self, count: isize) -> *const T
Calculates the offset from a pointer. count is in units of T; e.g. a
count of 3 represents a pointer offset of 3 * sizeof::<T>() bytes.
Safety
Both the starting and resulting pointer must be either in bounds or one byte past the end of an allocated object. If either pointer is out of bounds or arithmetic overflow occurs then any further use of the returned value will result in undefined behavior.
fn is_null(self) -> bool
Returns true if the pointer is null.
unsafe fn as_ref(&self) -> Option<&'a T>
: Option is not clearly the right return type, and we may want to tie the return lifetime to a borrow of the raw pointer
Returns None if the pointer is null, or else returns a reference to
the value wrapped in Some.
Safety
While this method and its mutable counterpart are useful for null-safety, it is important to note that this is still an unsafe operation because the returned value could be pointing to invalid memory.
unsafe fn offset(self, count: isize) -> *mut T
Calculates the offset from a pointer. count is in units of T; e.g. a
count of 3 represents a pointer offset of 3 * sizeof::<T>() bytes.
Safety
The offset must be in-bounds of the object, or one-byte-past-the-end.
Otherwise offset invokes Undefined Behaviour, regardless of whether
the pointer is used.
unsafe fn as_mut(&self) -> Option<&'a mut T>
: return value does not necessarily convey all possible information
Returns None if the pointer is null, or else returns a mutable
reference to the value wrapped in Some.
Safety
As with as_ref, this is unsafe because it cannot verify the validity
of the returned pointer.
Trait Implementations
impl<T> Send for Unique<T> where T: Send + ?Sized
Unique pointers are Send if T is Send because the data they
reference is unaliased. Note that this aliasing invariant is
unenforced by the type system; the abstraction using the
Unique must enforce it.
impl<T> Sync for Unique<T> where T: Sync + ?Sized
Unique pointers are Sync if T is Sync because the data they
reference is unaliased. Note that this aliasing invariant is
unenforced by the type system; the abstraction using the
Unique must enforce it.