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circuitpython/docs/library/ure.rst

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:mod:`ure` -- simple regular expressions
========================================
.. include:: ../templates/unsupported_in_circuitpython.inc
.. module:: ure
:synopsis: regular expressions
|see_cpython_module| :mod:`cpython:re`.
This module implements regular expression operations. Regular expression
syntax supported is a subset of CPython ``re`` module (and actually is
a subset of POSIX extended regular expressions).
Supported operators are:
``'.'``
Match any character.
``'[...]'``
Match set of characters. Individual characters and ranges are supported,
including negated sets (e.g. ``[^a-c]``).
``'^'``
``'$'``
``'?'``
``'*'``
``'+'``
``'??'``
``'*?'``
``'+?'``
``'|'``
``'(...)'``
Grouping. Each group is capturing (a substring it captures can be accessed
with `match.group()` method).
**NOT SUPPORTED**: Counted repetitions (``{m,n}``), more advanced assertions
(``\b``, ``\B``), named groups (``(?P<name>...)``), non-capturing groups
(``(?:...)``), etc.
Functions
---------
.. function:: compile(regex_str, [flags])
Compile regular expression, return `regex <regex>` object.
.. function:: match(regex_str, string)
Compile *regex_str* and match against *string*. Match always happens
from starting position in a string.
.. function:: search(regex_str, string)
Compile *regex_str* and search it in a *string*. Unlike `match`, this will search
string for first position which matches regex (which still may be
0 if regex is anchored).
.. data:: DEBUG
Flag value, display debug information about compiled expression.
.. _regex:
Regex objects
-------------
Compiled regular expression. Instances of this class are created using
`ure.compile()`.
.. method:: regex.match(string)
regex.search(string)
Similar to the module-level functions :meth:`match` and :meth:`search`.
Using methods is (much) more efficient if the same regex is applied to
multiple strings.
.. method:: regex.split(string, max_split=-1)
Split a *string* using regex. If *max_split* is given, it specifies
maximum number of splits to perform. Returns list of strings (there
may be up to *max_split+1* elements if it's specified).
Match objects
-------------
Match objects as returned by `match()` and `search()` methods.
.. method:: match.group([index])
Return matching (sub)string. *index* is 0 for entire match,
1 and above for each capturing group. Only numeric groups are supported.