Serde YAML

This crate is a Rust library for using the Serde serialization framework with data in YAML file format.

Dependency

[dependencies]
serde = "1.0"
serde_yaml = "0.9"

Release notes are available under GitHub releases.

Using Serde YAML

API documentation is available in rustdoc form but the general idea is:

use std::collections::BTreeMap;

fn main() -> Result<(), serde_yaml::Error> {
    // You have some type.
    let mut map = BTreeMap::new();
    map.insert("x".to_string(), 1.0);
    map.insert("y".to_string(), 2.0);

    // Serialize it to a YAML string.
    let yaml = serde_yaml::to_string(&map)?;
    assert_eq!(yaml, "x: 1.0\ny: 2.0\n");

    // Deserialize it back to a Rust type.
    let deserialized_map: BTreeMap<String, f64> = serde_yaml::from_str(&yaml)?;
    assert_eq!(map, deserialized_map);
    Ok(())
}

It can also be used with Serde's derive macros to handle structs and enums defined in your program.

[dependencies]
serde = { version = "1.0", features = ["derive"] }
serde_yaml = "0.9"

Structs serialize in the obvious way:

use serde::{Serialize, Deserialize};

#[derive(Debug, PartialEq, Serialize, Deserialize)]
struct Point {
    x: f64,
    y: f64,
}

fn main() -> Result<(), serde_yaml::Error> {
    let point = Point { x: 1.0, y: 2.0 };

    let yaml = serde_yaml::to_string(&point)?;
    assert_eq!(yaml, "x: 1.0\ny: 2.0\n");

    let deserialized_point: Point = serde_yaml::from_str(&yaml)?;
    assert_eq!(point, deserialized_point);
    Ok(())
}

Enums serialize using YAML's !tag syntax to identify the variant name.

use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize, PartialEq, Debug)]
enum Enum {
    Unit,
    Newtype(usize),
    Tuple(usize, usize, usize),
    Struct { x: f64, y: f64 },
}

fn main() -> Result<(), serde_yaml::Error> {
    let yaml = "
        - !Newtype 1
        - !Tuple [0, 0, 0]
        - !Struct {x: 1.0, y: 2.0}
    ";
    let values: Vec<Enum> = serde_yaml::from_str(yaml).unwrap();
    assert_eq!(values[0], Enum::Newtype(1));
    assert_eq!(values[1], Enum::Tuple(0, 0, 0));
    assert_eq!(values[2], Enum::Struct { x: 1.0, y: 2.0 });

    // The last two in YAML's block style instead:
    let yaml = "
        - !Tuple
          - 0
          - 0
          - 0
        - !Struct
          x: 1.0
          y: 2.0
    ";
    let values: Vec<Enum> = serde_yaml::from_str(yaml).unwrap();
    assert_eq!(values[0], Enum::Tuple(0, 0, 0));
    assert_eq!(values[1], Enum::Struct { x: 1.0, y: 2.0 });

    // Variants with no data can be written using !Tag or just the string name.
    let yaml = "
        - Unit  # serialization produces this one
        - !Unit
    ";
    let values: Vec<Enum> = serde_yaml::from_str(yaml).unwrap();
    assert_eq!(values[0], Enum::Unit);
    assert_eq!(values[1], Enum::Unit);

    Ok(())
}

License