ocaml-rust-parser-generator

This is a library for parsing and generating Rust in OCaml. It is essentially (mostly automatically) generated bindings for syn and proc-macro2.

Architecture

Data is communicated to and from OCaml using the Marshal module. Data structures are serialized to and deserialized from the corresponding binary format and given to taken or from OCaml in the form of bytes. To simplify writing functions that are executed from OCaml, ocaml-rs is used.

The modules of the project are in following folders:

• generator, a generator written in Rust
• rust-lib, a Rust library that is loaded from OCaml
• ocaml-lib, an OCaml library to be used by the end users

The main files containing code are:

• generator/src/main.rs, which generates from the syn.json file the following files:
  • rust-lib/src/generated.rs with marshaling code and parsing/generating code (if applicable) for each syn type
  • ocaml-lib/ocaml_rust_parser_generator.mli with types definitions and functions
  • ocaml-lib/ocaml_rust_parser_generator.ml with implementations that call the functions from the Marshal module and functions from the Rust library
• rust-lib/src/lib.rs with MarshalingOutput and MarshalingInput structs for marshaling OCaml values and hand-written marshaling code for some particular types

API

Below SynType mean almost any of the syn types.

type rs_syn_type = ...

val token_stream_of_string : string -> rs_token_stream
val string_of_token_stream : rs_token_stream -> string
val span_of_token_stream : rs_token_stream -> rs_span

val parse_syn_type_from_token_stream : rs_token_stream -> rs_syn_type
val parse_syn_type_from_string : string -> rs_syn_type
val generate_syn_type_to_token_stream : rs_syn_type -> rs_token_stream
val generate_syn_type_to_string : rs_syn_type -> string
val span_of_syn_type : rs_syn_type -> rs_span

Building and running

The library can be built by executing the following command (Rust and OCaml with Dune are required):

make build

An example, which demonstrates the usage of the library (round tripping a Rust file and getting parts from it) and also how Rustfmt can be used to make the output better (the shexp package from OPAM is required), can be run by executing the following command:

make example

License

This project is 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.