[SahilRajputdotexe]

This adds parsing of the match statement (PEP 634) to the Python 3.10 and later grammars. Refs #138, which discusses how to handle the soft keywords.

match and case are soft keywords, so match = 1, match(x) and match[0]: int have to keep working. A match that starts a logical line and whose line ends in a colon is parsed as the statement, anything else is a name. The parser also falls back to a name when case is not accepted as a keyword. This does not follow the demo branch linked in the issue, which makes the parser semi-LL(1). The lookahead here is a small wrapper around the token stream. No new tree classes are added. The new nodes are plain match_stmt, case_block and pattern nodes, and match_stmt and case_block are registered as flow containers.

The error finder reports what CPython reports for the new syntax, for example an irrefutable pattern that is not last, a repeated capture name, * patterns outside a sequence and bad mapping or class patterns. The diff parser and the pep8 normalizer also understand the statement.

import parso
module = parso.load_grammar(version='3.10').parse('match p:\n    case Point(x=0) | [0, *_]:\n        pass\n')

I ran the full test suite on Python 3.8 to 3.14 locally. New tests are in test_parser.py, test_diff_parser.py, test_pep8.py and failing_examples.py, which is compared against CPython's own messages on 3.10 and later.

[davidhalter]

LLM slop, closing.