[antlr-interest] Print an AST in original order

[Varun Bhargava]

Hi Kevin,

Thanks for replying. I'm using ANTLR for the first time and an absolute
beginner to Parsing stuff, so my apologies if I ask stupid questions.

Firstly, you are right. The tree does look as you mentioned. 
To print the tree I am using the ToStringTree() method of the CommonTree
class.

How do I insert the root between binary children? Here is the snippet
from my grammar file:

where	
	: 
	| WHERE^ filter 
	;

filter
	: //(key compare literal | key IS NOT? NULL | keyList IN key |
NOT filter | LPAREN filter RPAREN) (AND^ filter | OR^ filter)*
	(compareFilter | notNullFilter | keyListFilter | NOT filter |
LPAREN filter RPAREN) (AND^ filter | OR^ filter)*
	;

compareFilter 
	:	
	key compare (literal | PARAMETER)
	;
	
notNullFilter
	:
	key IS NOT? NULL
	;
	
keyListFilter
	:
	keyList IN key
	;
			
keyList
	: key (COMMA keyList)*	
	;

compare
	: EQ | NOTEQ | LT | GT | LTE | GTE



Thanks
Varun



-----Original Message-----
From: Kevin J. Cummings [mailto:cummings at kjchome.homeip.net] 
Sent: Wednesday, 30 July 2008 03:13
To: Varun Bhargava
Cc: antlr-interest at antlr.org
Subject: Re: [antlr-interest] Print an AST in original order

Varun Bhargava wrote:
> Hi All,
> 
> I'm using ANTLR3 for C# target. My problem is to load up a statement 
> into a tree, so some substitutions to the tree and then print out the 
> tree in original order to re-generate the input statement but with
some 
> substitutions.
> 
> I cannot seem to print the AST in its original order. For EG;
> 
>           WHERE
> 
>               |
> 
>              AND
> 
>            /       \
> 
>         =           =
> 
>       /   \        /  \
> 
>      A    5      b    10

Doesn't your tree actually look like this:?

WHERE
   |
  AND
   |
   = ------=
   |       |
   A - 5   b - 10

I think your problem comes in how you are interpreting your 
root/children associations.  Insert your root between binary children, 
or before a unary subtree (as if there is no LHS).  It seems to work for

this example....

> The above tree should be printed as WHERE A=5 AND b = 10
> 
> However this is not the case in ANTLR. Has anyone done this before? If

> yes could you please point me in the right direction or give me some 
> sample code?

What are you using to do this with?

> Thanks
> 
> Varun

-- 
Kevin J. Cummings
kjchome at rcn.com
cummings at kjchome.homeip.net
cummings at kjc386.framingham.ma.us
Registered Linux User #1232 (http://counter.li.org)