remagic

Build regular expressions from composable, typed Python objects. Partly inspired by magic-regexp for Node.

>>> import remagic as rm
>>> year = rm.DIGIT.times(4).group("year")
>>> month = rm.DIGIT.times(2).group("month")
>>> date = rm.START + year + "-" + month + rm.END
>>> date.compile().fullmatch("2027-01")["year"]
'2027'

Patterns are immutable. Strings are matched literally, + concatenates, | alternates, and (?:...) is added only where precedence needs it:

>>> str((rm.exactly("a") | "b").times(2))
'(?:a|b){2}'

Installation

uv add remagic            # or: pip install remagic
uv add "remagic[regex]"   # optional: the `regex` engine

Requires Python 3.11+. Patterns compile with the standard re module. Features that only regex supports, such as unicode_property("L"), switch to it automatically and need the regex extra.

Learn more

See the quickstart, concepts and cookbook in the docs, or the building blocks below.

Building blocks

• Constants: DIGIT, WORD, WHITESPACE, LETTER, CHAR, NEWLINE, ... and anchors START, END, WORD_BOUNDARY, ...
• Characters: exactly, char_in, char_not_in, char_range, any_of, unicode_property
• Quantifiers: optional, zero_or_more, one_or_more, times, between, at_least, each with lazy= and possessive=
• Groups: group (numbered or named), non_capturing, atomic, ref
• Assertions: before, not_before, after, not_after, and the methods followed_by, not_followed_by, preceded_by, not_preceded_by
• Flags: scoped, ignore_case, multiline, dotall
• Every function has a matching Pattern method.

Development

uv sync
uv run pytest        # 100% line and branch coverage is required
uv run ruff check . && uv run ruff format --check . && uv run mypy
uv run --group docs sphinx-build -W -b html docs docs/_build   # build the docs