Crate protobuf_codegen
source · [−]Expand description
Protobuf code generator for protobuf crate
This crate is useful mostly from build.rs scripts to generate .rs files during the build.
How to generate code
There are three main ways to generate .rs files from .proto files:
- using
protoccommand line tool andprotoc-gen-rustplugin - using this crate
Codegenwith pure rust parser - using this crate
Codegenwithprotocparser
Which one should you use depends on your needs.
If you are using non-cargo build system (like Bazel), you might prefer
using protoc-gen-rust plugin for protoc.
If you build with cargo, you probably want to use Codegen from this crate.
Protoc parser vs pure rust parser
There are two protobuf parsers which can be plugged into this crate:
protoc-based parser (protocis a command like utility from Google protobuf)- pure rust parser (
protobuf-parsecrate)
protoc-based parser is expected to parse .proto files very correctly:
all Google’s protobuf implementations rely on it.
Where there are no known bugs in protobuf-parse, it is not tested very well.
Also protobuf-parse does not implement certain rarely used features of .proto parser,
mostly complex message options specified in .proto files.
I never saw anyone using them, but you have been warned.
Note protoc command can be obtained from protoc-bin-vendored crate.
Version 3
Note this is documentation for protobuf-codegen version 3 (which is currently in development).
In version 3 this crate encapsulates both protoc-based codegen and pure rust codegen.
In version 2 protobuf-codegen contains protoc-based codegen,
and protobuf-codegen-pure is pure rust codegen.
Example
// Use this in build.rs
protobuf_codegen::Codegen::new()
.includes(&["src/protos"])
// Inputs must reside in some of include paths.
.input("src/protos/apple.proto")
.input("src/protos/banana.proto")
.out_dir("src/protos")
.run_from_script();