⚠️ This project is in its early early stages. expect bugs and missing features. ⚠️

About

A tool for generating zig code capable of de/serializing to the protocol buffer wire format. Depends on protoc to parse .proto files.

Status

• zig code generation
  • recursive message types don't work yet #1. see examples/recursive.proto
• deserialization from wire format
  • merging messages not yet implemented - 6 conformance failures
• serialization to wire format
• initial serialization to json format - 9 conformance failures
• [w] conformance testing results: 1489/408/15 success/skip/fail. the 408 skipped are in these categories:
  • json input
  • text format output
  • jspb format output

Usage

• download the protoc compiler
• make sure protoc is in your PATH

Note: this project has been tested against

$ protoc --version
libprotoc 21.5

Build

zig build

Run tests.

note: some of these depend on protoc being available.

zig build test

Generate .zig files from .proto files

$ zig build run -- -I examples/ examples/person.proto examples/only_enum.proto
# writes generated content to ./gen/ by default.  
# use --zig_out=/gen-path to specify different directory.

Note: all arguments after -- are forwarded to protoc.

This is equivalent to:

$ zig build
$ protoc --plugin=zig-out/bin/protoc-gen-zig --zig_out=gen -I examples/ examples/person.proto examples/only_enum.proto

Either of the above generate the following files in gen/:

$ ls gen
only_enum.pb.zig  person.pb.zig

Use the generated code

• see below for an example zig test command
• see build.zig for a packaging example

test "readme" {
    // Note - the package 'protobuf' below is src/lib.zig.  this package must
    // include itself. it can be provided in build.zig or on the command line
    // as shown below.    
    const std = @import("std");
    const pb = @import("protobuf");
    const Person = @import("generated").person.Person;

    // serialize to a writer
    const alloc = std.testing.allocator; // could be any zig std.mem.Allocator
    var zero = Person.initFields(.{
        .id = 1,
        .name = pb.extern_types.String.init("zero"),
        .kind = .NONE,
    });
    zero.set(.id, 0);
    var buf = std.ArrayList(u8).init(alloc);
    defer buf.deinit();
    try pb.protobuf.serialize(&zero.base, buf.writer());

    // deserialize from a buffer
    var ctx = pb.protobuf.context(buf.items, alloc);
    const message = try ctx.deserialize(&Person.descriptor);
    defer message.deinit(alloc);
    var zero_copy = try message.as(Person);

    // test that they're equal
    try std.testing.expect(zero_copy.has(.id));
    try std.testing.expectEqual(zero.id, zero_copy.id);
    try std.testing.expect(zero_copy.has(.name));
    try std.testing.expectEqualStrings(zero.name.slice(), zero_copy.name.slice());
    try std.testing.expect(zero_copy.has(.kind));
    try std.testing.expectEqual(zero.kind, zero_copy.kind);

    // serialize to json
    // const stderr = std.io.getStdErr().writer();
    const stderr = std.io.null_writer;
    try pb.json.serialize(&zero.base, stderr, .{
        .pretty_print = .{ .indent_size = 2 },
    });
    _ = try stderr.write("\n");
    // prints
    //{
    //  "name": "zero",
    //  "id": 0,
    //  "kind": "NONE"
    //}
}

$ zig test src/tests.zig --mod protobuf:protobuf:src/lib.zig --mod generated:protobuf:zig-cache/protobuf-zig/lib.zig --deps protobuf,generated

Resources

inspired by

• https://github.com/protobuf-c/protobuf-c
• https://github.com/mlugg/zigpb