protox

An implementation of the protobuf compiler in rust, intended for use as a library with crates such as prost-build to avoid needing to build protoc.

Examples

Compiling a single source file:

assert_eq!(protox::compile(["root.proto"], ["."]).unwrap(), FileDescriptorSet {
    file: vec![
        FileDescriptorProto {
            name: Some("root.proto".to_owned()),
            /* ... */
        }
    ],
});

Usage with prost-build:

let file_descriptors = protox::compile(["root.proto"], ["."]).unwrap();
prost_build::compile_fds(file_descriptors).unwrap();

Usage with tonic-build:

let file_descriptors = protox::compile(["root.proto"], ["."]).unwrap();

let file_descriptor_path = PathBuf::from(env::var_os("OUT_DIR").expect("OUT_DIR not set"))
    .join("file_descriptor_set.bin");
fs::write(&file_descriptor_path, file_descriptors.encode_to_vec()).unwrap();

tonic_build::Config::new()
    .file_descriptor_set_path(&file_descriptor_path)
    .skip_protoc_run()
    .compile_protos(["root.proto"], ["."])
    .unwrap();

Error messages

This crate uses miette to add additional details to errors. For nice error messages, add miette as a dependency with the fancy feature enabled and return a miette::Result from your build script.

fn main() -> miette::Result<()> {
  let _ = protox::compile(["root.proto"], ["."])?;

  Ok(())
}

Example error message:

Error:
  × name 'Bar' is not defined
   ╭─[root.proto:3:1]
 3 │ message Foo {
 4 │     Bar bar = 1;
   ·     ─┬─
   ·      ╰── found here
 5 │ }
   ╰────

Minimum Supported Rust Version

Rust 1.64 or higher.

The minimum supported Rust version may be changed in the future, but it will be done with a minor version bump.

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

This project includes code imported from the Protocol Buffers project, which is included under its original (BSD) license.

Contribution