ANTLR Group expressions and save Variables - antlr

Question

If I have expressions like:
(name = Paul AND age = 16) OR country = china;
And I want to get:
QUERY
|
|-------------|
() |
| |
AND OR
| |
|-------| |
name age country
| | |
Paul 16 china
How can I print the () and the condition (AND/OR) before the fields name, age country?
My grammar file is something like this:
parse
: block EOF -> block
;
block
: (statement)* (Return ID ';')?
-> ^(QUERY statement*)
;
statement
: assignment ';'
-> assignment
;
assignment
: expression (condition expression)*
-> ^(condition expression*)
| '(' expression (condition expression)* ')' (condition expression)*
-> ^(Brackets ^(condition expression*))
;
condition
: AND
| OR
;
Brackets: '()' ;
OR : 'OR' ;
AND : 'AND' ;
..
But it only prints the first condition that appears in the expression ('AND' in this example), and I can't group what is between brackets, and what is not...

Answer 1

Your grammar looks odd to me, and there are errors in it: if the parser does not match "()", you can't use Brackets inside a rewrite rule. And why would you ever want to have the token "()" inside your AST?
Given your example input:
(name = Paul AND age = 16) OR country = china;
here's possible way to construct an AST:
grammar T;
options {
output=AST;
}
query
: expr ';' EOF -> expr
;
expr
: logical_expr
;
logical_expr
: equality_expr ( logical_op^ equality_expr )*
;
equality_expr
: atom ( equality_op^ atom )*
;
atom
: ID
| INT
| '(' expr ')' -> expr
;
equality_op
: '='
| 'IS' 'NOT'?
;
logical_op
: 'AND'
| 'OR'
;
ID : ('a'..'z' | 'A'..'Z')+;
INT : '0'..'9'+;
WS : (' ' | '\t' | '\r' | '\n')+ {skip();};
which would result in this: