created_at2024-02-08 06:31:39.181452
updated_at2024-05-31 15:20:56.74332
descriptionA fully YAML 1.2 compliant YAML parser
David Aguilar (davvid)





yaml-rust2 is a fully compliant YAML 1.2 implementation written in pure Rust.

This work is based on yaml-rust with fixes towards being compliant to the YAML test suite. yaml-rust's parser is heavily influenced by libyaml and yaml-cpp.

yaml-rust2 is a pure Rust YAML 1.2 implementation that benefits from the memory safety and other benefits from the Rust language.

Quick Start

Add the following to the Cargo.toml of your project:

yaml-rust2 = "0.8"

Use yaml_rust2::YamlLoader to load YAML documents and access them as Yaml objects:

use yaml_rust2::{YamlLoader, YamlEmitter};

fn main() {
    let s =
    - list1
    - list2
    - 1
    - 2.0
    let docs = YamlLoader::load_from_str(s).unwrap();

    // Multi document support, doc is a yaml::Yaml
    let doc = &docs[0];

    // Debug support
    println!("{:?}", doc);

    // Index access for map & array
    assert_eq!(doc["foo"][0].as_str().unwrap(), "list1");
    assert_eq!(doc["bar"][1].as_f64().unwrap(), 2.0);

    // Array/map-like accesses are checked and won't panic.
    // They will return `BadValue` if the access is invalid.

    // Dump the YAML object
    let mut out_str = String::new();
        let mut emitter = YamlEmitter::new(&mut out_str);
        emitter.dump(doc).unwrap(); // dump the YAML object to a String
    println!("{}", out_str);

Note that yaml_rust2::Yaml implements Index<&'a str> and Index<usize>:

  • Index<usize> assumes the container is an array
  • Index<&'a str> assumes the container is a string to value map
  • otherwise, Yaml::BadValue is returned

If your document does not conform to this convention (e.g. map with complex type key), you can use the Yaml::as_XXX family API of functions to access your objects.


  • Pure Rust
  • Vec/HashMap access API
  • Low-level YAML events emission


This library does not try to interpret any type specifiers in a YAML document, so there is no risk of, say, instantiating a socket with fields and communicating with the outside world just by parsing a YAML document.

Specification Compliance

This implementation is fully compatible with the YAML 1.2 specification. In order to help with compliance, yaml-rust2 tests against (and passes) the YAML test suite.

Upgrading from yaml-rust

You can use yaml-rust2 as a drop-in replacement for the original yaml-rust crate.

yaml-rust = { version = "#.#", package = "yaml-rust2" }

This Cargo.toml declaration allows you to refer to this crate as yaml_rust in your code.

use yaml_rust::{YamlLoader, YamlEmitter};


Licensed under either of

at your option.

Since this repository was originally maintained by chyh1990, there are 2 sets of licenses. A license of each set must be included in redistributions. See the LICENSE file for more details.

You can find licences in the .licenses subfolder.


Fork this repository and Create a Pull Request on Github. You may need to click on "compare across forks" and select your fork's branch. Make sure that Ethiraric is selected as the base repository, not chyh1990.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.


Commit count: 408

cargo fmt