A humble code generator

humblegen is a highly experimental code generator written in Rust that allows defining data structures in a custom language and generating declarations as serialization and deserialization implementations in target languages. It is similar to protobuf but focuses on simple uses cases (i.e. small applications) where simplicity trumps performance. Core design goals are:

• Support Rust and Elm.
• Use JSON on the wire.
• As indistinguishable from hand-written serialization code as possible.

Installation

You can compile and install humblegen directly from github:

$ cargo install --git https://github.com/mbr/humblegen-rs

Usage

Create a Check out generator/tests/rust/showcase/spec.humble for an overview of the format. Then write your own humblespec in protocol.humble

API docs

humblegen -l docs protocol.humble

Elm

rm -rf Protocol
mkdir Protocol
humblegen -l elm -o Protocol --elm-module-root "Protocol" protocol.humble

Add the following dependencies

# 1.0.8
elm install elm/bytes
#1.0.3
elm install danfishgold/base64-bytes
# 1.1.3
elm install rtfeldman/elm-iso8601-date-strings
# 3.2.1
elm install justinmimbs/date
# 1.0.0
elm install elm/time

Rust

humblegen -l rust -o protocol.rs  protocol.humble

Use the generated protocol.rs using include!("../protocol.rs") or similar.

Wherever you use the generated code, put the following into Cargo.toml:

[dependencies]
humblegen-rt = "(match your humblegen version here)"
serde = { version = "1.0.110", features = [ "derive" ] }
tokio = { version = "0.2.20", features = ["rt-threaded", "tcp", "macros"] }

build.rs

humblegen can be used in your build.rs directly, this has the advantage of automatically recompiling the Rust program whenever the underlying spec changes. To enable, you should first add humblegen to your build dependencies:

[build-dependencies]
humblegen = "*"

(Using cargo add --build via cargo edit is recommended instead)

Then, add the following line to build.rs:

humblegen::build("path/to/spec.humble").expect("compile humble");

Finally, import the module (which in this version of humblegen is always in a file called protocol.rs):

mod protocol {
    include!(concat!(env!("OUT_DIR"), "/protocol.rs"));
}