📁 /snap/core20/current/lib/python3.8/lib2to3/PatternGrammar.txt
# Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
# A grammar to describe tree matching patterns.
# Not shown here:
# - 'TOKEN' stands for any token (leaf node)
# - 'any' stands for any node (leaf or interior)
# With 'any' we can still specify the sub-structure.
# The start symbol is 'Matcher'.
Matcher: Alternatives ENDMARKER
Alternatives: Alternative ('|' Alternative)*
Alternative: (Unit | NegatedUnit)+
Unit: [NAME '='] ( STRING [Repeater]
| NAME [Details] [Repeater]
| '(' Alternatives ')' [Repeater]
| '[' Alternatives ']'
)
NegatedUnit: 'not' (STRING | NAME [Details] | '(' Alternatives ')')
Repeater: '*' | '+' | '{' NUMBER [',' NUMBER] '}'
Details: '<' Alternatives '>'