#codec #lcm

rust-lcm-codec

Rust support for reading and writing the LCM data format

2 releases

✓ Uses Rust 2018 edition

0.2.1 Jun 19, 2020
0.2.0 Feb 12, 2020

#39 in Encoding

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rust-lcm-codec

Rust support for reading and writing the LCM data format.

Overview

rust-lcm-codec is a Rust project for interacting with LCM encoded data. Other aspects of LCM, like an RPC mechanism, are not supported by this project.

The rust-lcm-codec API is derived from the combination of the rust-lcm-codec runtime library and code generated from your LCM type specification data definitions/schemas by rust-lcm-codegen.

TODO

  • Works for no_std, no global allocator (read: embedded) use cases.
  • Builds on stable Rust.
  • Minimize performance costs of de/serialization.
  • Maximize de/serialization correctness through use of session types.
  • No rustc or clippy warnings in generated code.
  • Support multidimensional arrays.
  • Rigorously test for cross-implementation compatibility.

Getting Started

This project requires a Rust (stable) toolchain. The recommended toolchain management system in Rust is rustup.

There are two key components to the rust-lcm-codec workflow:

  1. Setup up your build.rs to use rust-lcm-codegen to generate API code.
  2. Use the generated rust-lcm-codec API to interact with LCM encoded data.

Usage

rust-lcm-codegen setup

Add the following dependencies to your Rust project's Cargo.toml:

[dependencies]
rust-lcm-codec = "0.1.0"

[build-dependencies]
rust-lcm-codegen = "0.1.0"

Import rust-lcm-codegen:generate in your Rust project's build.rs file, and point the generate function at your .lcm schemas and desired output location for the generated code:

use rust_lcm_codegen::generate;
use std::env;
use std::fs::File;
use std::io::Read;
use std::path::Path;

fn main() {
    println!("cargo:rerun-if-changed=../schemas");
    println!("cargo:rerun-if-changed=../../src");
    println!("cargo:rerun-if-changed=../../../rust-lcm-codegen");

    let schema_files = vec![
        "./schemas/example_schema_a.lcm",
        "path/to/schemas/example_schema_b.lcm",
    ];
    let out_dir = env::var("OUT_DIR").expect("OUT_DIR");
    let out_path = Path::join(Path::new(&out_dir), "generated_lcm_api.rs");
    generate(schema_files, &out_path);
}

Include the generated API in your Rust project's code:

#![allow(non_snake_case)]
include!(concat!(env!("OUT_DIR"), "/generated_lcm_api.rs"));

Generated API

Based on the above setup the generated types and API from your LCM schemas would be in a file named generated_lcm_api.rs in the OUT_DIR from your last cargo build or cargo test attempt.

You can find the location of this file this using:

find ./target/ -name generated_lcm_api.rs -printf "%T@ %Tc %p\n" | sort -n

The file referenced at the end of the list will be the most recent one generated.

See tests for more examples of how to use the de/serializers exposed by the generated crate for the example schemas included with this project.

Tests

To run the tests for this project make sure you're in /rust-lcm-codec and then run:

cargo test

License

See LICENSE for more details.

Copyright 2020 Auxon Corporation

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

No runtime deps