projects / rustc.git / blame
| Commit | Line | Data |
|---|---|---|
| 416331ca XL |
1 | # memoffset # |
| 2 | ||
| 3 | [](https://crates.io/crates/memoffset) | |
| 4 | ||
| 5 | C-Like `offset_of` functionality for Rust structs. | |
| 6 | ||
| 7 | Introduces the following macros: | |
| 8 | * `offset_of!` for obtaining the offset of a member of a struct. | |
| 9 | * `span_of!` for obtaining the range that a field, or fields, span. | |
| 10 | ||
| 11 | `memoffset` works under `no_std` environments. | |
| 12 | ||
| 13 | ## Usage ## | |
| 14 | Add the following dependency to your `Cargo.toml`: | |
| 15 | ||
| 16 | ```toml | |
| 17 | [dependencies] | |
| 18 | memoffset = "0.2" | |
| 19 | ``` | |
| 20 | ||
| 21 | Add the following lines at the top of your `main.rs` or `lib.rs` files. | |
| 22 | ||
| 23 | ```rust | |
| 24 | #[macro_use] | |
| 25 | extern crate memoffset; | |
| 26 | ``` | |
| 27 | ||
| 28 | ## Examples ## | |
| 29 | ```rust | |
| 30 | #[repr(C, packed)] | |
| 31 | struct Foo { | |
| 32 | a: u32, | |
| 33 | b: u32, | |
| 34 | c: [u8; 5], | |
| 35 | d: u32, | |
| 36 | } | |
| 37 | ||
| 38 | assert_eq!(offset_of!(Foo, b), 4); | |
| 39 | assert_eq!(offset_of!(Foo, c[3]), 11); | |
| 40 | ||
| 41 | assert_eq!(span_of!(Foo, a), 0..4); | |
| 42 | assert_eq!(span_of!(Foo, a .. c), 0..8); | |
| 43 | assert_eq!(span_of!(Foo, a .. c[1]), 0..9); | |
| 44 | assert_eq!(span_of!(Foo, a ..= c[1]), 0..10); | |
| 45 | assert_eq!(span_of!(Foo, ..= d), 0..14); | |
| 46 | assert_eq!(span_of!(Foo, b ..), 4..17); | |
| 47 | ``` |