This module provides everything necessary to parse and generate Tom's Obvious, Minimal Language (TOML) documents.

As described in the TOML documentation:

TOML aims to be a minimal configuration file format that's easy to read due to obvious semantics. TOML is designed to map unambiguously to a hash table. TOML should be easy to parse into data structures in a wide variety of languages.

Example TOML Document

# This is a TOML document.

title = "TOML Example"

[owner]
name = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00-08:00 # First class dates

[database]
server = "192.168.1.1"
ports = [ 8001, 8001, 8002 ]
connection_max = 5000
enabled = true

[servers]

# Indentation (tabs and/or spaces) is allowed but not required
[servers.alpha]
ip = "10.0.0.1"
dc = "eqdc10"

[servers.beta]
ip = "10.0.0.2"
dc = "eqdc10"

[clients]
data = [ ["gamma", "delta"], [1, 2] ]

# Line breaks are OK when inside arrays
hosts = [
"alpha",
"omega"
]

Parsing

Use the parseToml() top-level function to parse a TOML document into a TomlTable:

import ceylon.toml {
    parseToml, TomlTable, TomlParseException
}
import ceylon.time.timezone {
    ZoneDateTime
}

value sampleDocument = ...;
TomlTable|TomlParseException table = parseToml(sampleDocument);
if (is TomlParseException table) {
    throw table;
}
assert (is TomlTable owner = table["owner"]);
assert (is String ownerName = owner["name"]);
assert (is ZoneDateTime ownerDOB = owner["dob"]);
print("``ownerName`` was born at ``ownerDOB``");

Convenience getters such as TomlTable.getString() and TomlTable.getZoneDateTimeOrNull() can be used when the item type is known:

TomlTable owner = table.getTomlTable("owner");
String ownerName = owner.getString("name");
ZoneDateTime? ownerDOB = owner.getZoneDateTimeOrNull("dob");
print("``ownerName`` was born at ``ownerDOB else "an unknown time!"``");

TomlTables are also MutableLists, and TomlTables are also MutableMaps, and can be iterated and modified as regular collections:

String people =
   "[[people]]
        firstName = \"Joe\"
        lastName = \"Blow\"

    [[people]]
        firstName = \"John\"
        lastName = \"Smith\"
   ";
assert (is TomlTable data = parseToml(people));
data.getTomlArray("people").add {
    TomlTable {
        "firstName" -> "Jane",
        "lastName" -> "Doe"
    };
};
for (person in data.getTomlArray("people")) {
    assert (is TomlTable person);
    print("``person.getString("lastName")``, \
           ``person.getString("firstName")``");
}

outputs:

Blow, Joe
Smith, John
Doe, Jane

Error Handling

parseToml() returns the union TomlTable|TomlParseException. If a TomlParseException is returned, it will contain:

• a brief description of the first error that was found and a count of the total number of errors,

• a listing of all errors, including line number information, and

• a TomlTable containing the portions of the document that could be parsed without error.

The following program can be used to parse a document and report all errors, if any:

import ceylon.toml {
    parseToml, TomlTable, TomlParseException
}

String tomlDocument = ...;
switch (result = parseToml(tomlDocument))
case (is TomlParseException) {
    printAll {
        separator = "\n";
        result.errors.map((e) => "error: ``e``");
    };
    print("\n``result.errors.size`` errors\n");
}
case (is TomlTable) {
    // process(result);
}

Generating TOML Documents

formatToml() can be used to generate a TOML document from a TomlTable or a Map<Anything, Anything>. In either case, the argument must represent a valid TOML document, with Strings for keys and TomlValues, Maps, or Lists for values.

The code below produces a portion of the “Exampe TOML Document”:

    import ceylon.time.timezone {
        zoneDateTime, timeZone
    }
    import ceylon.toml {
        TomlTable, TomlArray, formatToml
    }

    shared void run() {
        value document = TomlTable {
            "title" -> "TOML Example",
            "owner" -> TomlTable {
                "name" -> "Tom Preston-Werner",
                "dob" -> zoneDateTime {
                    timeZone = timeZone.offset {
                        hours = -8;
                    };
                    year = 1979;
                    month = 5;
                    date = 27;
                    hour = 7;
                    minutes = 32;
                }
            },
            "hosts" -> TomlArray {
                "alpha", "omega"
            }
        };
        print(formatToml(document));
    }