formatparse

A Rust-backed reimplementation of the parse library for Python. It targets the same parse / search / findall workflow with substantially lower overhead on hot paths (performance guide). Use it as a drop-in replacement for common parse patterns; see the migration guide for edge-case differences.

Documentation

Full documentation: https://formatparse.readthedocs.io/

• Getting Started
• User Guides — patterns, datetime, custom types, validation, security
• API Reference
• FAQ / Troubleshooting
• Security — read before parsing untrusted input
• Changelog

Features

• Fast: Rust backend with pattern caching and batch APIs (benchmarks)
• Drop-in replacement: Compatible with common parse usage (migration guide)
• Pattern matching: Named and positional fields, custom types, nested specs
• DateTime parsing: ISO 8601, log timestamps, strftime, and more
• Case-sensitive and case-insensitive matching (matching behavior)
• Validation and bidirectional patterns for round-trip format/parse workflows

Installation

pip install formatparse

From source, see Installation in the docs.

Quick Start

from formatparse import parse, search, findall

result = parse("{name}: {age:d}", "Alice: 30")
print(result.named["name"], result.named["age"])  # Alice 30

More examples: Getting Started.

Malformed patterns: parse vs compile

For some invalid patterns (for example a missing } after a field), parse returns None while compile raises PatternParseMismatch. See the migration guide.

Custom types (extra_types)

Use @with_pattern and an extra_types dict — see the Custom types guide. Caching and pickling notes are documented there and in FAQ.

Contributing

See CONTRIBUTING.md and the Contributing docs page.

Testing

• Python: 740+ tests (pytest tests/), coverage enforced at 86%+ in CI
• Rust: formatparse-core and formatparse-pyo3 tests (cargo test -p formatparse-core --all-targets)

export PYTEST_DISABLE_PLUGIN_AUTOLOAD=1
pytest tests/

License

MIT License — see LICENSE.

Credits

Based on the parse library by Richard Jones.