Rather than use rewrite operators, use the operators themselves. The names of the rules are really parse points (and so they appear in the parse tree)and not AST node points. So:
expression : assignmentExpression -> ^(EXPRESSION assignmentExpression) ; assignmentExpression : listConcatExpression (ASSIGN^ listConcatExpression )* ; And so on... Jim > -----Original Message----- > From: [email protected] [mailto:antlr-interest- > [email protected]] On Behalf Of keith smillie > Sent: Thursday, May 13, 2010 5:05 AM > To: [email protected] > Subject: [antlr-interest] Flattening my expression tree. > > Hi All, > > I have a simple grammar which describes expressions. Everything seems > fine > but the resulting tree is very verbose and I was wondering if someone > could > suggest how to flatten it. > > The expression part of the grammar looks something like this, with the > expressions nested in order of precedence. > > expression > : assignmentExpression > -> ^(EXPRESSION assignmentExpression) > ; > > assignmentExpression > : x+=listConcatExpression (ASSIGN x+=listConcatExpression )* > -> ^(ASSIGNMENT_EXPRESSION $x+) > ; > > listConcatExpression > : x+=logicalExpression (COLON x+=logicalExpression)* > -> ^(LIST_EXPRESSION $x+) > ; > > logicalExpression > : x+=relationalExpression (o1=logicalOperators > x+=relationalExpression)* > > -> ^(LOGICAL_EXPRESSION $o1* $x+) > ; > > If I parse an expression such as: '1 + 2' I get the following tree > which > seems far too verbose. > > ASSIGNMENT_EXPRESSION > LIST_EXPRESSION > LOGICAL_EXPRESSION > RELATIONAL_EXPRESSION > ADDITION_EXPRESSION > + > MULTIPLY_EXPRESSION > UNARY_EXPRESSION > > SUBSCRIPT_EXPRESSION > > NUMBER > > 1 > MULTIPLY_EXPRESSION > UNARY_EXPRESSION > > SUBSCRIPT_EXPRESSION > > NUMBER > > 2 > > I would like the resulting tree to be flattened into something like the > following. Has anyone got any suggestions? > > ADDITION_EXPRESSION > + > NUMBER > 1 > NUMBER > 2 > > Regards, Keith > > List: http://www.antlr.org/mailman/listinfo/antlr-interest > Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your- > email-address List: http://www.antlr.org/mailman/listinfo/antlr-interest Unsubscribe: http://www.antlr.org/mailman/options/antlr-interest/your-email-address -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
