Crate flatty

Expand description

Flat message buffers with direct mapping to Rust types without packing/unpacking.

Main traits

Flat - type that occupies a single contiguous memory area. Guaranteed to always have the same binary representation on the same platform.
Portable - flat type that has stable platform-independent binary representation and therefore it can be safely transfered between different platforms (of even different endianness).

Unit type (()).
Signed and unsigned integers (u8, i8, u16, i16, u32, i32, u64, i64, u128, i128, usize, isize).
Floating-point numbers (f32, f64).
Array of some sized flat type ([T; N]where T:FlatSized).

User can create new composite types by using flat macro.

#[flatty::flat]
struct SizedStruct {
    a: u8,
    b: u16,
    c: u32,
    d: [u64; 4],
}

For enum you may explicitly set the type of tag (default value is u8).

#[flatty::flat(tag_type = "u32")]
enum SizedEnum {
    A,
    B(u16, u8),
    C { a: u8, b: u16 },
    D(u32),
}

Unsized struct is DST. The reference to that structure contains its size.

#[flatty::flat(sized = false)]
struct UnsizedStruct {
    a: u8,
    b: u16,
    c: flatty::FlatVec<u64>,
}

Rust doesn’t support DST enums yet so for now enum declaration is translated to unsized structure.

But it has as_ref/as_mut methods that returns a native enum that contains references to original enum fields.

#[flatty::flat(sized = false)]
enum UnsizedEnum {
    A,
    B(u8, u16),
    C { a: u8, b: flatty::FlatVec<u8, u16> },
}

flat
Attribute macro that creates a flat type from struct or enum declaration.