hun_offsetof

Provides C-like macros: offsetof and containerof

和memoffset crate的区别- Differences between crate memoffset and crate self

1. 基于指针操作，不占用栈空间，支持超大数据结构，无栈溢出风险
2. Pointer-based opertions do not occupy stack space, support super-large data structures, and avoid stack overflow risks.
3. 提供container_of操作
4. Provides the container_of operation.

基于指针的操作属于unsafe范围，如果使用声明宏方式，可能出现嵌套unsafe的编译告 警，而过程宏可以消除这类告警。 Pointer-based operations are unsafe, If the declaration macro mode is used, nested unsafe compilation warnings may be generated, which can be eliminated by procedure macro.

interfaces

rust offset_of!(type, member) -> usize; container_of!(&obj, type, member) -> &type; container_of_mut!(&obj, type, member) -> &mut type;

Examples

```rust

extern crate hun_offsetof as hun;

[repr(C)]

struct Bar { key: i32, value: i32, }

[repr(C)]

struct Foo { key: i32, value: [Bar; 2], }

asserteq!(hun::offsetof!(Bar, value), 4); asserteq!(hun::offsetof!(Foo, value[1].key), 12);

let foo = Foo { key: 1, value: [ Bar { key: 2, value: 2}, Bar { key: 3, value: 3 }], }; let value = &foo.value[1].value;

let obj = unsafe { hun::containerof!(value, Foo, value[1].value) }; asserteq!(obj as *const _, &foo as *const _); ```