deser-toml

TOML 1.1 support for deser. TOML is the format of choice for configuration files that humans edit, and those humans make mistakes. This crate is built to tell them exactly where: errors carry line, column and (with deser-path) the path to the value, also for internally tagged enums whose tag comes after the fields.

use deser::{Deserialize, Serialize};

#[derive(Debug, Serialize, Deserialize)]
struct Config {
    name: String,
    servers: Vec<Server>,
}

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

let config: Config = deser_toml::from_str(r#"
name = "web"

[[servers]]
host = "a.example.com"
port = 8080
"#).unwrap();
assert_eq!(config.servers[0].port, 8080);

// sequences of maps are written as arrays of tables
assert_eq!(
    deser_toml::to_string(&config).unwrap(),
    concat!(
        "name = \"web\"\n\n",
        "[[servers]]\nhost = \"a.example.com\"\nport = 8080\n",
    )
);

// errors point at the problem
let err = deser_toml::from_str::<Config>(
    "name = \"web\"\nservers = [{host = \"a\", port = 80800}]",
)
.unwrap_err();
assert_eq!((err.line(), err.column()), (Some(2), Some(32)));

A from scratch implementation of TOML 1.1 which passes the toml-test suite.
Date-times are passed through deser as the well-known Datetime extension type which falls back to strings. The date and time types of jiff, chrono and time can be used directly with the respective features of deser.
Arbitrarily nested arrays and inline tables do not overflow the stack.
The serializer writes maps as tables and sequences of maps as arrays of tables. The output is compatible with TOML 1.0.
Source locations (see deser::TrackLocations).
from_reader and to_writer work with std::io, the configurations with deser::io and async runtimes (deser-tokio).

Conformance tests

The test data is vendored in tests/data and can be updated with scripts/update-toml-test-data.sh. Run the suite with:

cargo test -p deser-toml --test toml_test_suite

Pass parts of test names to only run some tests and to see the details of failures, including known ones:

cargo test -p deser-toml --test toml_test_suite -- \
    valid/string invalid/table

Every valid test is also serialized again and has to roundtrip. Tests that are expected to fail are listed in tests/toml_test_suite_known_failures.txt. The run fails if a test fails that is not listed there or if a listed test passes. After fixing tests, update the list with:

DESER_TOML_BLESS=1 cargo test -p deser-toml --test toml_test_suite

deser-toml 0.10.1

deser-toml

Conformance tests