Lean buffer

Rust macro for structs to leverage flatbuffers serialization without *.fbs files and without bloated generated code.

There is no support for enums and complicated nesting. Keep it simple silly.

Show me the code

use std::rc::Rc;

use flatbuffers::FlatBufferBuilder;
use lean_buffer::{
    macros::LeanBufferWrite,
    traits::{AdapterExt, Factory, FactoryExt},
};

#[derive(LeanBufferWrite)]
struct Entity {
    t_i64: i64,
}

enum EnumSupport {
  NO,
  YES { e: Entity }
}

type TupleSupport = (Entity, Entity);

include!(concat!(env!("OUT_DIR"), "/Entity_lb_gen.rs"));

fn main() {
    let mut builder = FlatBufferBuilder::new();

    let factory = Factory::<Entity> {
        phantom_data: std::marker::PhantomData,
    };
    let f = Rc::new(factory) as Rc<dyn FactoryExt<Entity>>;
    let mut e1 = f.new_object();

    e1.t_i64 = 0x1337833F;
    let e1_t_i64 = e1.t_i64;

    let a1 = Box::new(e1) as Box<dyn AdapterExt>;

    // flatten
    a1.flatten(&mut builder);
    let data = builder.finished_data();

    // inflate
    let first_offset: usize = data[0].into();

    unsafe {
        let mut table = flatbuffers::Table::new(data, first_offset);
        let resurrected_e1 = f.inflate(&mut table);

        if resurrected_e1.t_i64 == e1_t_i64 {
            println!("Hello world! {}", resurrected_e1.t_i64);
        } else {
            println!("Goodbye cruel world! {}", resurrected_e1.t_i64);
        }
    }
}

Usage

Please see the struct with scalar values and struct with vector values.

Make sure that your cargo project, contains a build.rs file, albeit an empty one.

Longer description

This is a macro library, for Rust, that generates extension traits that leverage flatbuffers to flatten struct objects in Vec<u8>, which can be used later to reinflate them again as struct objects.

The required code is generated in one step.

All without the aid of *.fbs files and flatc.

This can be, in its turn, leveraged to facilitate inter-process / thread / channel communication.

Requirements

To use this library, a build.rs, with an (empty) fn main is required, in your crate project.

PRs are welcome!

...

TODO

• IDEA: Replace custom trait with Copy trait, so its flat buffer bytes can be copied
• lean-buffer-internal begs to be put in its own project, with its non-regexp, tokenization, file merging features. Working name: rs-ast-bundler?
• Benchmark: Is it optimal to pack in this order 64 bit, Vectors, then 32 bit, 16 bit etc.? Is the current implementation good enough?