Lib/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 '>'