Crate toml

source ·
Expand description

A serde-compatible TOML-parsing library

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

[package]
name = "toml"
version = "0.4.2"
authors = ["Alex Crichton <alex@alexcrichton.com>"]

[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();

Modules§

  • de
    Deserializing TOML into Rust structures.
  • map
    A map of String to Value.
  • ser
    Serializing Rust structures into TOML.
  • value
    Definition of a TOML value

Macros§

Structs§

  • Deserializer
    Deserialization TOML document
  • Spanned
    A spanned value, indicating the range at which it is defined in the source.

Enums§

  • Value
    Representation of a TOML value.

Functions§

  • from_str
    Deserializes a string into a type.

Type Aliases§

  • Table
    Type representing a TOML table, payload of the Value::Table variant. By default it is backed by a BTreeMap, enable the preserve_order feature to use a LinkedHashMap instead.