toml-tstring

TOML rendering for PEP 750 t-strings. Parsing and rendering happen in Rust; this package is the Python wrapper.

Requires Python 3.14+.

This package depends on tstring-bindings, a native PyO3 extension. On supported platforms, install from prebuilt wheels. Other environments require a local Rust 1.94.0 toolchain build.

API

render_data(template, profile="1.1")  # -> Python data
render_text(template, profile="1.1")  # -> TOML text
render_result(template, profile="1.1")  # -> RenderResult (.text + .data)

Type alias: TomlProfile = Literal["1.0", "1.1"]

Parsed template structure is cached per process using template.strings + profile as the key. Use profile="1.0" when you need the stricter TOML 1.0 behavior.

How it works

The Python Template is converted to a Rust token stream and parsed into TOML nodes -- assignments, key paths, headers, arrays, inline tables, literals, and string families all become explicit nodes with interpolation preserved. Rendering is driven by the parsed node type. The Rust toml crate handles value materialization and normalization.

Supported positions

• whole-value, key, dotted-key, table-header, and array-of-table interpolation
• string-fragment interpolation across all four TOML string types
• nested arrays, inline tables, and array-of-table sections
• integer forms (hex, binary, octal), special floats (inf, nan)
• datetime, date, and time values

Limits

• None rejected (TOML has no null)
• offset time values rejected
• integers must fit signed 64-bit range
• values must be TOML-representable

Verify

uv sync --group dev
uv run --group dev pytest

See also

• Project README
• Backend support matrix