rust

YAMLStar Rust Binding

YAML 1.2 loader for Rust using the libyamlstar shared library.

Overview

YAMLStar is a Rust binding for the YAMLStar library - a pure YAML 1.2 implementation written in Clojure. This binding provides a fast, spec-compliant YAML parser with zero Rust dependencies beyond the FFI layer.

Quick Start

use yamlstar::YAMLStar;
use serde::Deserialize;

#[derive(Deserialize)]
struct Config {
    host: String,
    port: u16,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let ys = YAMLStar::new()?;

    // Load YAML to dynamic type
    let data: serde_json::Value = ys.load("key: value")?;

    // Load YAML to typed struct
    let config: Config = ys.load("host: localhost\nport: 8080")?;

    // Load multiple documents
    let docs: Vec<String> = ys.load_all("---\ndoc1\n---\ndoc2")?;

    Ok(())
}

Installation

Add to your Cargo.toml:

[dependencies]
yamlstar = "0.1"
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"

Installing the Shared Library

The binding requires libyamlstar.so to be available at runtime. You have several options:

Option 1: Build from source

cd libyamlstar
make native

Option 2: Install to system

# Copy to system library directory
sudo cp libyamlstar/lib/libyamlstar.so.0.1.3 /usr/local/lib/

Option 3: Use LD_LIBRARY_PATH

export LD_LIBRARY_PATH=/path/to/libyamlstar/lib:$LD_LIBRARY_PATH
cargo run

API Reference

YAMLStar::new() -> Result<Self, Error>

Creates a new YAMLStar instance. This initializes the GraalVM isolate for thread-safe YAML parsing.

YAMLStar::load<T>(&self, yaml: &str) -> Result<T, Error>

Loads a single YAML document and deserializes it into type T. The type must implement serde::de::DeserializeOwned.

Example:

let config: Config = ys.load("host: localhost\nport: 8080")?;

YAMLStar::load_all<T>(&self, yaml: &str) -> Result<Vec<T>, Error>

Loads all YAML documents from a multi-document string and returns them as a Vec<T>.

Example:

let docs: Vec<String> = ys.load_all("---\ndoc1\n---\ndoc2")?;

YAMLStar::version(&self) -> Result<String, Error>

Returns the version string of the underlying YAMLStar library.

Features

• 100% YAML 1.2 Core Schema Compliance: Implements the full YAML 1.2 specification
• Type-Safe: Generic deserialization using Serde
• Zero-Copy where possible: Efficient FFI layer
• Thread-Safe: Each YAMLStar instance has its own GraalVM isolate

Known Limitations

• Special Float Values: While YAML 1.2 supports .inf, -.inf, and .nan, these values cannot be serialized to JSON by the underlying library and will result in an error

Examples

Run the included example:

cd rust
make example

Or with cargo:

LD_LIBRARY_PATH=../libyamlstar/lib cargo run --example load_yaml

Testing

make test

Or with cargo:

LD_LIBRARY_PATH=../libyamlstar/lib cargo test

YAML 1.2 Core Schema

YAMLStar implements the YAML 1.2 Core Schema with the following type mappings:

YAML Type	Rust Type
!!null	None, ()
!!bool	bool
!!int	i64, u64, etc.
!!float	f64, f32
!!str	String, &str
!!map	HashMap, structs
!!seq	Vec, arrays

Requirements

• Rust 1.70 or higher
• libyamlstar shared library (built with GraalVM)
• Linux or macOS (other platforms not yet supported)

License

MIT License - Copyright 2024 yaml.org

See License file for details.

Related Projects

• YAMLStar - Core YAML 1.2 implementation in Clojure
• YAMLScript - Programming language that compiles to YAML