Crate taplo[][src]


The main purpose of the library is to provide tools for analyzing TOML data where the layout must be preserved and the original position of every parsed token must be known. It can also format TOML documents.

It uses Rowan for the syntax tree, and every character is preserved from the input, including all comments and white space.

A DOM can be constructed for data-oriented analysis where each node wraps a part of the syntax tree with additional information and functionality.

Taplo also exposes a Value type that can be created from DOM nodes and can be serialized with Serde allowing for conversion to JSON, YAML or any other format.

TOML serialization is currently not implemented, but it is planned with a low priority.


  • chrono: Use chrono for TOML dates and times
  • time: Use time for TOML dates and times

chrono and time are mutually exclusive, if neither is set dates will be treated as strings.

  • serde: Support for serde
  • schema: Enable schema-related utilities and built-in schemas.
  • rewrite: Enable DOM manipulation features (WIP!)


A TOML document has to be parsed with parse first, it will build a syntax tree that can be traversed.

If there were no syntax errors during parsing, then a DOM root node can be constructed. It will build a DOM tree and validate the TOML document according to the specification. A DOM tree can be constructed even with syntax errors present, however parts of it will be missing.

If any errors ocurred, they will be collected in the root node. In that case the DOM must be analyzed with caution as parts of it might be missing.

const SOURCE: &str =
"value = 1
value = 2

string = 'some string'";

let parse_result = parse(SOURCE);

// Check for syntax errors.
// These are not carried over to DOM errors.

let root_node = parse_result.into_dom();

// Check for semantic errors.
// In this example "value" is a duplicate key.
assert_eq!(root_node.errors().len(), 1);


pub use rowan;



This module contains various methods and utilities for analyzing the DOM and/or the syntax tree.


This module contains the DOM for TOML source.


This module is used to format TOML.


TOML document to syntax tree parsing.


Declaration of the syntax tokens and lexer implementation.


This module is used to convert the DOM nodes into the values they contain.