1 # Copyright 2006 Google, Inc. All Rights Reserved.

     2 # Licensed to PSF under a Contributor Agreement.

     3 

     4 # A grammar to describe tree matching patterns.

     5 # Not shown here:

     6 # - 'TOKEN' stands for any token (leaf node)

     7 # - 'any' stands for any node (leaf or interior)

     8 # With 'any' we can still specify the sub-structure.

     9 

    10 # The start symbol is 'Matcher'.

    11 

    12 Matcher: Alternatives ENDMARKER

    13 

    14 Alternatives: Alternative ('|' Alternative)*

    15 

    16 Alternative: (Unit | NegatedUnit)+

    17 

    18 Unit: [NAME '='] ( STRING [Repeater]

    19                  | NAME [Details] [Repeater]

    20                  | '(' Alternatives ')' [Repeater]

    21                  | '[' Alternatives ']'

    22 		 )

    23 

    24 NegatedUnit: 'not' (STRING | NAME [Details] | '(' Alternatives ')')

    25 

    26 Repeater: '*' | '+' | '{' NUMBER [',' NUMBER] '}'

    27 

    28 Details: '<' Alternatives '>'