Struct std::ptr::Shared
[−]
[src]
pub struct Shared<T> where T: ?Sized {
// some fields omitted
}A wrapper around a raw *mut T that indicates that the possessor
of this wrapper has shared ownership of the referent. Useful for
building abstractions like Rc<T> or Arc<T>, which internally
use raw pointers to manage the memory that they own.
Methods
impl<T> Shared<T> where T: ?Sized
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>
ptr_as_ref #27780): 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>
ptr_as_ref #27780): 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 Behavior, regardless of whether
the pointer is used.
unsafe fn as_mut(&self) -> Option<&'a mut T>
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 Shared<T> where T: ?Sized
Shared pointers are not Send because the data they reference may be aliased.
impl<T> !Sync for Shared<T> where T: ?Sized
Shared pointers are not Sync because the data they reference may be aliased.