Antlr Tree Grammar

2
votes

I am having trouble moving from parser grammar to tree grammar, the problem comes when i use tree operators (^,!) instead of rewrite rules (->)

where_clause
    :   'where'! condition_or
    ;

condition_or
    :   condition_and ( 'or'^ condition_and )*
    ;

condition_and
    :   condition_expr ( 'and'^ condition_expr )*
    ;

condition_expr
    :   condition_comparision
//  |   condition_in
//  |   condition_like
    ;

condition_comparision
    :   column_identifier ('=' | '!=' | '>' | '<')^ sql_element
    ;

For the above parser grammar, how would the tree grammer look like ? Since this isn't recursive I wont be able to collapse this into a single rule in the tree grammar.

The other alternative to forcefully rewrite the parser grammar using rewrite syntax

condition_or
    :   condition_and -> condition_and 
     ( 'or' x=condition_and -> ^('or' condition_or $x))*
    ;

Is there any simpler way to do this ?

Thanks

1
javatreeantlrgrammarabstract-syntax-tree

1 Answers

2
votes

The corresponding tree grammar would look like this:

where_clause
    :   condition_or
    ;

condition_or
    :   ^('or' condition_and condition_and)
    ;

condition_and
    :   ^('and' condition_expr condition_expr)
    ;

condition_expr
    :   condition_comparision
    ;

condition_comparision
    :   ^('=' column_identifier sql_element)
    |   ^('!=' column_identifier sql_element)
    |   ^('>' column_identifier sql_element)
    |   ^('<' column_identifier sql_element)
    ;