Reading configuration

Tome reads TOML 1.0 into a small family of typed values. It keeps table entries in source order and returns a TomlError when a document cannot be read. There is no coercion between a string, an integer and a float.

import tome

let assert Ok(config) = tome.parse("[server]\nhost = 'localhost'\nport = 8080")
let assert Some(port) = tome.path(config, ["server", "port"])
assert tome.as_int(port) == Some(8080)

get reads one table key. path follows several table keys; an empty path returns the original value. Use at for a zero-based array position. Missing keys, wrong shapes and out-of-range positions return None.

Reading a file

parse accepts text. parse_bytes accepts a BitArray and checks UTF-8 before reading the document, including bytes hidden in comments.

import pooka/file
import tome

let assert Ok(bytes) = file.read_bytes("settings.toml")
match tome.parse_bytes(bytes) {
  Ok(config) -> echo tome.path(config, ["server", "host"])
  Error(problem) -> echo tome.describe(problem)
}

Run the complete example from examples/config with pooka run.

The values

A parsed document is always a TTable, behind the Toml base class.

Value	Contents
`TString`	Decoded text
`TInt`	An integer, including base-prefixed integers
`TFloat`	A finite floating-point number
`TInfinity`	Whether infinity is positive
`TNan`	TOML's not-a-number value
`TBool`	A Boolean
`TDateTime`, `TDate`, `TTime`	The validated original spelling
`TArray`	A list of `Toml` values
`TTable`	A list of key/value pairs in source order

Dates retain fractional precision and offsets. The permitted space between a date and time becomes T; Tome does not convert time zones or truncate fractions. Infinity and NaN have explicit classes because the BEAM does not expose them as ordinary floating-point values.

Arrays of tables use TArray containing TTable values. Later child headers belong to the latest table in that array. Inline tables are closed values; later declarations cannot add fields to them.

When a document is wrong

TomlError holds a one-based line and a message. describe joins them into a sentence, such as line 3: a value is missing. LF and CRLF both count as one newline. A byte input that cannot be decoded reports its encoding error at the start of the document.

The parser targets TOML 1.0. Its Pooka tests include the upstream TOML 1.0 corpus, with expected values for valid documents, plus accessor, ordering and error-location tests. TOML 1.1 additions are outside this version's scope.