toml

A serde-compatible TOML decoder and encoder for Rust.

For format-preserving editing or finer control over output, see toml_edit

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/license/mit)

at your option.

Contribution

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.

lib.rs:

A serde-compatible TOML-parsing library

TOML itself is a simple, ergonomic, and readable configuration format:

[package]
name = "toml"

[dependencies]
serde = "1.0"

The TOML format tends to be relatively common throughout the Rust community for configuration, notably being used by Cargo, Rust's package manager.

TOML values

A TOML document is represented with the Table type which maps String to the Value enum:

pub enum Value {
    String(String),
    Integer(i64),
    Float(f64),
    Boolean(bool),
    Datetime(Datetime),
    Array(Array),
    Table(Table),
}

Parsing TOML

The easiest way to parse a TOML document is via the Table type:

use toml::Table;

let value = "foo = 'bar'".parse::<Table>().unwrap();

assert_eq!(value["foo"].as_str(), Some("bar"));

The Table type implements a number of convenience methods and traits; the example above uses FromStr to parse a [str] into a Table.

Deserialization and Serialization

This crate supports serde 1.0 with a number of implementations of the Deserialize, Serialize, Deserializer, and Serializer traits. Namely, you'll find:

• Deserialize for Table
• Serialize for Table
• Deserialize for Value
• Serialize for Value
• Deserialize for Datetime
• Serialize for Datetime
• Deserializer for de::Deserializer
• Serializer for ser::Serializer
• Deserializer for Table
• Deserializer for Value

This means that you can use Serde to deserialize/serialize the Table type as well as Value and Datetime type in this crate. You can also use the Deserializer, Serializer, or Table type itself to act as a deserializer/serializer for arbitrary types.

An example of deserializing with TOML is:

use serde::Deserialize;

#[derive(Deserialize)]
struct Config {
    ip: String,
    port: Option<u16>,
    keys: Keys,
}

#[derive(Deserialize)]
struct Keys {
    github: String,
    travis: Option<String>,
}

let config: Config = toml::from_str(r#"
    ip = '127.0.0.1'

    [keys]
    github = 'xxxxxxxxxxxxxxxxx'
    travis = 'yyyyyyyyyyyyyyyyy'
"#).unwrap();

assert_eq!(config.ip, "127.0.0.1");
assert_eq!(config.port, None);
assert_eq!(config.keys.github, "xxxxxxxxxxxxxxxxx");
assert_eq!(config.keys.travis.as_ref().unwrap(), "yyyyyyyyyyyyyyyyy");

You can serialize types in a similar fashion:

use serde::Serialize;

#[derive(Serialize)]
struct Config {
    ip: String,
    port: Option<u16>,
    keys: Keys,
}

#[derive(Serialize)]
struct Keys {
    github: String,
    travis: Option<String>,
}

let config = Config {
    ip: "127.0.0.1".to_string(),
    port: None,
    keys: Keys {
        github: "xxxxxxxxxxxxxxxxx".to_string(),
        travis: Some("yyyyyyyyyyyyyyyyy".to_string()),
    },
};

let toml = toml::to_string(&config).unwrap();