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Rust `offsetof` prototype (`offset_of` and `span_of`)
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| pub use std::mem | |
| #[macro_export] | |
| macro_rules! offset_of { | |
| ($sty:ty, $($field:tt)+) => ({ | |
| unsafe { | |
| let root: $sty = $crate::mem::uninitialized(); | |
| let base = &root as *const _ as usize; | |
| let end = &root.$($field)* as *const _ as usize; | |
| end - base | |
| } | |
| }); | |
| } | |
| #[cfg(test)] | |
| mod tests { | |
| #[test] | |
| fn offset_assert() { | |
| use super::*; | |
| #[repr(C)] | |
| struct Member { | |
| foo: u32, | |
| } | |
| #[repr(C)] | |
| struct Test { | |
| x: u64, | |
| y: [u8; 56], | |
| z: Member, | |
| egg: [[u8; 4]; 4], | |
| } | |
| assert_eq!(offset_of!(Test, x), 0); | |
| assert_eq!(offset_of!(Test, y), 8); | |
| assert_eq!(offset_of!(Test, y[4]), 12); | |
| assert_eq!(offset_of!(Test, z.foo), 64); | |
| assert_eq!(offset_of!(Test, egg[1][3]), 75); | |
| } | |
| } |
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| pub use std::mem | |
| #[macro_export] | |
| macro_rules! span_of { | |
| (@helper $root:ident, [] ..=) => { | |
| compile_error!("Expected a range, found '..='") | |
| }; | |
| (@helper $root:ident, [] ..) => { | |
| compile_error!("Expected a range, found '..'") | |
| }; | |
| (@helper $root:ident, [] ..= $($field:tt)+) => { | |
| (&$root as *const _ as usize, | |
| &$root.$($field)* as *const _ as usize + $crate::mem::size_of_val(&$root.$($field)*)) | |
| }; | |
| (@helper $root:ident, [] .. $($field:tt)+) => { | |
| (&$root as *const _ as usize, &$root.$($field)* as *const _ as usize) | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ [] ..= $($end:tt)+) => { | |
| (&$root.$($begin)* as *const _ as usize, | |
| &$root.$($end)* as *const _ as usize + $crate::mem::size_of_val(&$root.$($end)*)) | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ [] .. $($end:tt)+) => { | |
| (&$root.$($begin)* as *const _ as usize, &$root.$($end)* as *const _ as usize) | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ [] ..) => { | |
| (&$root.$($begin)* as *const _ as usize, | |
| &$root as *const _ as usize + $crate::mem::size_of_val(&$root)) | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ [] ..=) => { | |
| compile_error!( | |
| "Found inclusive range to the end of a struct. Did you mean '..' instead of '..='?") | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ []) => { | |
| compile_error!("The second argument of 'span_of!' must be a range") | |
| }; | |
| (@helper $root:ident, $(# $begin:tt)+ [] $tt:tt $($rest:tt)*) => { | |
| span_of!(@helper $root, $(#$begin)* #$tt [] $($rest)*) | |
| }; | |
| (@helper $root:ident, [] $tt:tt $($rest:tt)*) => { | |
| span_of!(@helper $root, #$tt [] $($rest)*) | |
| }; | |
| ($sty:ty, $($exp:tt)+) => ({ | |
| unsafe { | |
| let root: $sty = $crate::mem::uninitialized(); | |
| let base = &root as *const _ as usize; | |
| let (begin, end) = span_of!(@helper root, [] $($exp)*); | |
| begin-base..end-base | |
| } | |
| }); | |
| } | |
| #[cfg(test)] | |
| mod tests { | |
| #[test] | |
| fn span_assert() { | |
| use super::*; | |
| #[repr(C)] | |
| struct Member { | |
| foo: u32, | |
| } | |
| #[repr(C)] | |
| struct Test { | |
| x: u64, | |
| y: [u8; 56], | |
| z: Member, | |
| egg: [[u8; 4]; 4], | |
| } | |
| assert_eq!(span_of!(Test, ..x), 0..0); | |
| assert_eq!(span_of!(Test, ..=x), 0..8); | |
| assert_eq!(span_of!(Test, ..y), 0..8); | |
| assert_eq!(span_of!(Test, ..=y), 0..64); | |
| assert_eq!(span_of!(Test, ..y[0]), 0..8); | |
| assert_eq!(span_of!(Test, ..=y[0]), 0..9); | |
| assert_eq!(span_of!(Test, ..z), 0..64); | |
| assert_eq!(span_of!(Test, ..=z), 0..68); | |
| assert_eq!(span_of!(Test, ..z.foo), 0..64); | |
| assert_eq!(span_of!(Test, ..=z.foo), 0..68); | |
| assert_eq!(span_of!(Test, ..egg), 0..68); | |
| assert_eq!(span_of!(Test, ..=egg), 0..84); | |
| assert_eq!(span_of!(Test, ..egg[0]), 0..68); | |
| assert_eq!(span_of!(Test, ..=egg[0]), 0..72); | |
| assert_eq!(span_of!(Test, ..egg[0][0]), 0..68); | |
| assert_eq!(span_of!(Test, ..=egg[0][0]), 0..69); | |
| assert_eq!(span_of!(Test, x..), | |
| offset_of!(Test, x)..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, y..), | |
| offset_of!(Test, y)..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, y[0]..), | |
| offset_of!(Test, y[0])..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, z..), | |
| offset_of!(Test, z)..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, z.foo..), | |
| offset_of!(Test, z.foo)..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, egg..), | |
| offset_of!(Test, egg)..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, egg[0]..), | |
| offset_of!(Test, egg[0])..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, egg[0][0]..), | |
| offset_of!(Test, egg[0][0])..mem::size_of::<Test>()); | |
| assert_eq!(span_of!(Test, x..y), | |
| offset_of!(Test, x)..offset_of!(Test, y)); | |
| assert_eq!(span_of!(Test, x..=y), | |
| offset_of!(Test, x)..offset_of!(Test, y) + mem::size_of::<[u8; 56]>()); | |
| assert_eq!(span_of!(Test, x..y[4]), | |
| offset_of!(Test, x)..offset_of!(Test, y[4])); | |
| assert_eq!(span_of!(Test, x..=y[4]), | |
| offset_of!(Test, x)..offset_of!(Test, y) + mem::size_of::<[u8; 5]>()); | |
| assert_eq!(span_of!(Test, x..z.foo), | |
| offset_of!(Test, x)..offset_of!(Test, z.foo)); | |
| assert_eq!(span_of!(Test, x..=z.foo), | |
| offset_of!(Test, x)..offset_of!(Test, z.foo) + mem::size_of::<u32>()); | |
| assert_eq!(span_of!(Test, egg[0][0]..egg[1][0]), | |
| offset_of!(Test, egg[0][0])..offset_of!(Test, egg[1][0])); | |
| } | |
| } |
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