.. | ||
src | ||
.cargo-checksum.json | ||
build.rs | ||
Cargo.toml | ||
CHANGELOG.md | ||
LICENSE | ||
README.md |
memoffset
C-Like offset_of
functionality for Rust structs.
Introduces the following macros:
offset_of!
for obtaining the offset of a member of a struct.offset_of_tuple!
for obtaining the offset of a member of a tuple. (Requires Rust 1.20+)offset_of_union!
for obtaining the offset of a member of a union.span_of!
for obtaining the range that a field, or fields, span.
memoffset
works under no_std
environments.
If you're using a rustc version greater or equal to 1.77, this crate's offset_of!()
macro simply forwards to core::mem::offset_of!()
.
Usage
Add the following dependency to your Cargo.toml
:
[dependencies]
memoffset = "0.9"
These versions will compile fine with rustc versions greater or equal to 1.19.
Examples
use memoffset::{offset_of, span_of};
#[repr(C, packed)]
struct Foo {
a: u32,
b: u32,
c: [u8; 5],
d: u32,
}
fn main() {
assert_eq!(offset_of!(Foo, b), 4);
assert_eq!(offset_of!(Foo, d), 4+4+5);
assert_eq!(span_of!(Foo, a), 0..4);
assert_eq!(span_of!(Foo, a .. c), 0..8);
assert_eq!(span_of!(Foo, a ..= c), 0..13);
assert_eq!(span_of!(Foo, ..= d), 0..17);
assert_eq!(span_of!(Foo, b ..), 4..17);
}
Usage in constants
memoffset
has support for compile-time offset_of!
on rust>=1.65.
On versions below 1.77, this is an incomplete implementation with one caveat:
Due to dependence on #![feature(const_refs_to_cell)]
, you cannot get the offset of a Cell
field in a const-context.