[antlr-interest] A few questions about AST

[Jim Idle]

The rules:

 

projection
    :    PROJ LBRACK listAttribut RBRACK relation
    -> ^(PROJ listAttribut relation);

listAttribut
    :    (attribut) (','! attribut)*;

 

Can be:

 

tokens

{

                ATTRIB;

}

 

listAttribut

                : a1=attribute (',' a2+=attribute) -> ^(ATTRIB $a1 $a2*)
;

 

Though there are other ways to formulate this of course. 

 

The rules:

 

predicat:    elementaryPredicat (logicalOperator elementaryPredicat)*; 
//    -> ^(logicalOperator elementaryPredicat elementaryPredicat);
logicalOperator 
    :    AND
        | OR;

 

can be:

 

predicat:    elementaryPredicat (^logicalOperator elementaryPredicat)*; 


logicalOperator: AND | OR;

 

 

Parsing the resulting tree is done via a tree parser produced by tree
grammar or by manually traversing the tree. You need to read the book
and/or examples for more details.

 

Jim.

 

 

 

From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of G R
Sent: Monday, June 25, 2007 6:54 AM
To: antlr-interest at antlr.org
Subject: [antlr-interest] A few questions about AST

 

Hi,
I'm actually testing ANTLR to translate a relational algebra query into
SQL query for my "end of school project". Anyway, reading the wiki and
FAQ on the web site there are still a few things that i don't know how
to do. 

So here is my first question :
I got this Parser rules 

projection
    :    PROJ LBRACK listAttribut RBRACK relation
    -> ^(PROJ listAttribut relation);

listAttribut
    :    (attribut) (','! attribut)*;

When i look at my AST, i got every attributes as child of my node PROJ.
I'd like to know how can I create an imaginary children "Attributes" to
PROJ and list every attributes in the subtree Attributes. 
Instead of having :
PROJ
|______attribut1
|______attribut2
|...
|______relation
I'd like to have
PROJ
|_____Attributs
|         |______attribut1
|         |______attribut2
|_____relation 

The second question is... How can i make a node using a parser rule ?
here is an example : I got the following rule

predicat:    elementaryPredicat (logicalOperator elementaryPredicat)*; 
//    -> ^(logicalOperator elementaryPredicat elementaryPredicat);
logicalOperator 
    :    AND
        | OR;

As you can see I've try to make my node using the logical operator but
this don't work. 
Is there anyway of doing such things?

Finally, a simple question...How do i parse the AST from my main program
in java ?
Thanks.

G. R.

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