A low-level interface for writing out TOML

Considerations when serializing arbitrary data:

• Verify the implementation with toml-test-harness
• Be sure to group keys under a table before writing another table
• Watch for extra trailing newlines and leading newlines, both when starting with top-level keys or a table
• When serializing an array-of-tables, be sure to verify that all elements of the array serialize as tables
• Standard tables and inline tables may need separate implementations of corner cases, requiring verifying them both

When serializing Rust data structures

• Option: Skip key-value pairs with a value of None, otherwise error when seeing None
  • When skipping key-value pairs, be careful that a deeply nested None doesn't get skipped
• Scalars and arrays are unsupported as top-level data types
• Tuples and tuple variants seriallize as arrays
• Structs, struct variants, and maps serialize as tables
• Newtype variants serialize as to the inner type
• Unit variants serialize to a string
• Unit and unit structs don't have a clear meaning in TOML

Example

use toml_write::TomlWrite as _;

let mut output = String::new();
output.newline()?;
output.open_table_header()?;
output.key("table")?;
output.close_table_header()?;
output.newline()?;

output.key("key")?;
output.space()?;
output.keyval_sep()?;
output.space()?;
output.value("value")?;
output.newline()?;

assert_eq!(output, r#"
[table]
key = "value"
"#);

toml_write

A low-level interface for writing out TOML

License

This project is licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in toml-rs by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.