zig-msgpack

A MessagePack implementation for the Zig programming language. This library provides a simple and efficient way to serialize and deserialize data using the MessagePack format.

An article introducing it: Zig Msgpack

Features

Full MessagePack Support: Implements all MessagePack types including the timestamp extension.
Timestamp Support: Complete implementation of MessagePack timestamp extension type (-1) with support for all three formats (32-bit, 64-bit, and 96-bit).
Efficient: Designed for high performance with minimal memory overhead.
Type-Safe: Leverages Zig's type system to ensure safety during serialization and deserialization.
Simple API: Offers a straightforward and easy-to-use API for encoding and decoding.

Installation

Version Compatibility

Zig Version	Library Version	Status
0.13 and older	0.0.6	Legacy support
0.14.0	Current	✅ Fully supported
0.15.x	Current	✅ Fully supported
0.16.0-dev (nightly)	Current	✅ Supported with compatibility layer

Note: For Zig 0.13 and older versions, please use version 0.0.6 of this library. Note: Zig 0.16+ removes std.io.FixedBufferStream, but this library provides a compatibility layer to maintain the same API across all supported versions.

For Zig 0.14.0, 0.15.x, and 0.16.0-dev, follow these steps:

Add as a dependency: Add the library to your build.zig.zon file. You can fetch a specific commit or branch.
```
zig fetch --save https://github.com/zigcc/zig-msgpack/archive/{COMMIT_OR_BRANCH}.tar.gz
```

Configure your build.zig: Add the zig-msgpack module to your executable.

const std = @import("std");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    const exe = b.addExecutable(.{
        .name = "my-app",
        .root_source_file = .{ .path = "src/main.zig" },
        .target = target,
        .optimize = optimize,
    });

    const msgpack_dep = b.dependency("zig_msgpack", .{
        .target = target,
        .optimize = optimize,
    });

    exe.root_module.addImport("msgpack", msgpack_dep.module("msgpack"));

    b.installArtifact(exe);
}

Usage

Basic Usage

const std = @import("std");
const msgpack = @import("msgpack");

pub fn main() !void {
    const allocator = std.heap.page_allocator;
    var buffer: [1024]u8 = undefined;
    
    // Use the compatibility layer for cross-version support
    const compat = msgpack.compat;
    var write_buffer = compat.fixedBufferStream(&buffer);
    var read_buffer = compat.fixedBufferStream(&buffer);

    const BufferType = compat.BufferStream;
    var packer = msgpack.Pack(
        *BufferType, *BufferType,
        BufferType.WriteError, BufferType.ReadError,
        BufferType.write, BufferType.read,
    ).init(&write_buffer, &read_buffer);

    // Create and encode data
    var map = msgpack.Payload.mapPayload(allocator);
    defer map.free(allocator);
    try map.mapPut("name", try msgpack.Payload.strToPayload("Alice", allocator));
    try map.mapPut("age", msgpack.Payload.uintToPayload(30));
    try packer.write(map);

    // Decode
    read_buffer.pos = 0;
    const decoded = try packer.read(allocator);
    defer decoded.free(allocator);
    
    const name = (try decoded.mapGet("name")).?.str.value();
    const age = (try decoded.mapGet("age")).?.uint;
    std.debug.print("Name: {s}, Age: {d}\n", .{ name, age });
}

Data Types

// Basic types
const nil_val = msgpack.Payload.nilToPayload();
const bool_val = msgpack.Payload.boolToPayload(true);
const int_val = msgpack.Payload.intToPayload(-42);
const uint_val = msgpack.Payload.uintToPayload(42);
const float_val = msgpack.Payload.floatToPayload(3.14);

// String and binary
const str_val = try msgpack.Payload.strToPayload("hello", allocator);
const bin_val = try msgpack.Payload.binToPayload(&[_]u8{1, 2, 3}, allocator);

// Array
var arr = try msgpack.Payload.arrPayload(2, allocator);
try arr.setArrElement(0, msgpack.Payload.intToPayload(1));
try arr.setArrElement(1, msgpack.Payload.intToPayload(2));

// Extension type
const ext_val = try msgpack.Payload.extToPayload(5, &[_]u8{0xaa, 0xbb}, allocator);

Timestamp Usage

// Create timestamps
const ts1 = msgpack.Payload.timestampFromSeconds(1234567890);
const ts2 = msgpack.Payload.timestampToPayload(1234567890, 123456789);

// Write and read timestamp
try packer.write(ts2);
read_buffer.pos = 0;
const decoded_ts = try packer.read(allocator);
defer decoded_ts.free(allocator);

std.debug.print("Timestamp: {}s + {}ns\n", 
    .{ decoded_ts.timestamp.seconds, decoded_ts.timestamp.nanoseconds });
std.debug.print("As float: {d}\n", .{ decoded_ts.timestamp.toFloat() });

Error Handling

// Type conversion with error handling
const int_payload = msgpack.Payload.intToPayload(-42);
const uint_result = int_payload.getUint() catch |err| switch (err) {
    msgpack.MsGPackError.INVALID_TYPE => {
        std.debug.print("Cannot convert negative to unsigned\n");
        return;
    },
    else => return err,
};

API Overview

msgpack.Pack: The main struct for packing and unpacking MessagePack data. It is initialized with read and write contexts.
msgpack.Payload: A union that represents any MessagePack type. It provides methods for creating and interacting with different data types (e.g., mapPayload, strToPayload, mapGet).

Implementation Notes

Zig 0.16 Compatibility

Starting from Zig 0.16, the standard library underwent significant changes to the I/O subsystem. The std.io.FixedBufferStream was removed as part of a broader redesign. This library includes a compatibility layer (src/compat.zig) that:

Provides a BufferStream implementation for Zig 0.16+ that mimics the behavior of the old FixedBufferStream
Uses conditional compilation to maintain backward compatibility with Zig 0.14 and 0.15
Ensures all existing functionality works seamlessly across different Zig versions

This means you can use the same API regardless of your Zig version, and the library will handle the differences internally.

Testing

To run the unit tests for this library, use the following command:

zig build test

# For more detailed test output
zig build test --summary all

Documentation

To generate documentation for this library:

zig build docs

Contributing

Contributions are welcome! Please feel free to open an issue or submit a pull request.

License

This project is licensed under the MIT License. See the LICENSE file for details.

Dependents

README