pub unsafe trait Delta: Copy + Eq {
type Error;
// Required methods
fn sub(a: *mut u8, b: *mut u8) -> Result<Self, Self::Error>;
unsafe fn sub_unchecked(a: *mut u8, b: *mut u8) -> Self;
unsafe fn add(self, a: *const u8) -> *mut u8;
}Expand description
Delta trait generalizes differences in
memory locations to types like i8 and i16
Note: certain invariants must be upheld to fulfill the unsafe contract of this trait, these invariants are detailed in each function
This trait is intended to be used with RelPtr
Required Associated Types§
Required Methods§
Sourcefn sub(a: *mut u8, b: *mut u8) -> Result<Self, Self::Error>
fn sub(a: *mut u8, b: *mut u8) -> Result<Self, Self::Error>
The difference between two pointers
Note: for all values of a: *mut u8,
you must enforce that Delta::sub(a, a) == Delta::ZERO
and that the following function does not panic for all values
of a and b
fn for_all_a_b(a: *mut u8, b: *mut u8) {
if let Some(x) = Self::sub(a, b) {
unsafe { assert_eq!(Self::add(x, b), a) }
}
}Sourceunsafe fn sub_unchecked(a: *mut u8, b: *mut u8) -> Self
unsafe fn sub_unchecked(a: *mut u8, b: *mut u8) -> Self
The difference between two pointers
Note: for all values of a: *mut u8,
you must enforce that Delta::sub(a, a) == Delta::ZERO
and that the following function does not panic for all values
of a and b if the difference between a and b is valid
fn for_all_a_b(a: *mut u8, b: *mut u8) {
unsafe { assert_eq!(Self::add(Self::sub_unchecked(a, b), b), a) }
}Safety:
If the difference between a and b is not
representable by Self is UB
Sourceunsafe fn add(self, a: *const u8) -> *mut u8
unsafe fn add(self, a: *const u8) -> *mut u8
Adds the difference (in self) to the pointer a
Note: for all values of a: *mut u8,
you must enforce that Delta::add(Delta::ZERO, a) == a
and that the following function does not panic for all values
of a and b
fn for_all_a_b(a: *mut u8, b: *mut u8) {
if let Some(x) = Self::sub(a, b) {
unsafe { assert_eq!(Self::add(x, b), a) }
}
}§Safety
TODO
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.