[antlr-interest] Change type of current AST

[Dimitrios Kolovos]

I've found that the following works (in case anyone faces a similar
issue in the future):

additiveExpression
	:	multiplicativeExpression (('+'^|'-'^) multiplicativeExpression
		{if (root_0.getToken() != null) root_0.getToken().setType(Operator);})*
	;

I'm sure there is a more elegant way but this will do for now...

Cheers,
Dimitrios

On Fri, Jun 6, 2008 at 11:39 PM, Dimitrios Kolovos <dskolovos at gmail.com> wrote:
> I actually have the book in front of me and have spent quite a few hours
> looking at several v3 examples but I can't seem to figure out how to do
> something which looks dead simple (at least from my v2 experience) :(
>
> Just FYI, the .token thing is syntactically ok but $tree at that point is
> null and thus, $tree.token throws an NPE. I'll start looking at the
> generated code to see if I can figure out how I can do it there and then
> copy the solution into the grammar.
>
> In any case thanks a lot for your time and for providing this excellent tool
> for free.
>
> Cheers,
> Dimitrios
>
> Terence Parr wrote:
>>
>> ok, i'm not going to predict code anymore for you...please start reading
>> the source or book or examples:
>>
>>    /** A single token is the payload */
>>    public Token token;
>>
>> try it with that field.
>> Ter
>> On Jun 6, 2008, at 3:15 PM, Dimitrios Kolovos wrote:
>>
>>> Unfortunately this doesn't work as it generates
>>>
>>> if ( state.backtracking==0 ) {
>>>  ((Token)((CommonTree)retval.tree).payload).setType(Operator);
>>> }
>>>
>>> which doesn't compile as CommonTree doesn't have a payload field...
>>>
>>> Cheers,
>>> Dimitrios
>>>
>>> On Fri, Jun 6, 2008 at 10:46 PM, Terence Parr <parrt at cs.usfca.edu> wrote:
>>>>
>>>> Oh, right.  ((Token)$tree.payload).setType(Operator) would do it.
>>>> Ter
>>>> On Jun 6, 2008, at 2:37 PM, Dimitrios Kolovos wrote:
>>>>
>>>>> If I set ASTLabelType=CommonType, $tree.type = Operator; it generates
>>>>>
>>>>> if ( state.backtracking==0 ) {
>>>>> ((CommonTree)retval.tree).type = Operator;
>>>>> }
>>>>>
>>>>> which is incorrect as CommonTree doesn't have a "type" field
>>>>>
>>>>> (without an ASTLabelType = it generates
>>>>>
>>>>> if ( state.backtracking==0 ) {
>>>>> ((Object)retval.tree).type = Operator;
>>>>> }
>>>>>
>>>>> which is also (profoundly) incorrect
>>>>> )
>>>>>
>>>>> Cheers,
>>>>> Dimitrios
>>>>>
>>>>> Terence Parr wrote:
>>>>>>
>>>>>> Oh, well $tree.type = foo; is what you want.
>>>>>> Ter
>>>>>> On Jun 6, 2008, at 1:50 PM, Dimitrios Kolovos wrote:
>>>>>>
>>>>>>> Thanks for your prompt reply. It seems we are getting closer (but
>>>>>>> still
>>>>>>> no cigar :)
>>>>>>>
>>>>>>> both $tree = and $additiveExpression.tree = produce
>>>>>>>
>>>>>>> if ( state.backtracking==0 ) {
>>>>>>> retval.tree = Operator;
>>>>>>> }
>>>>>>>
>>>>>>> which does not seem to change the type of the AST (the getType()
>>>>>>> returns
>>>>>>> the value of a generated field named T_97). Everything else in the
>>>>>>> grammar
>>>>>>> seems to be working fine (no warnings, expected ASTs).
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Dimitrios
>>>>>>>
>>>>>>>
>>>>>>> Terence Parr wrote:
>>>>>>>>
>>>>>>>> Try $tree = or $additiveExpression.tree =  I believe.No doubt you
>>>>>>>> are
>>>>>>>> getting an error from antlr below?
>>>>>>>> Ter
>>>>>>>> On Jun 6, 2008, at 1:17 PM, Dimitrios Kolovos wrote:
>>>>>>>>
>>>>>>>>> Hi Ter,
>>>>>>>>>
>>>>>>>>> Unfortunately, that doesn't seem to work either.
>>>>>>>>>
>>>>>>>>> additiveExpression
>>>>>>>>> :    multiplicativeExpression (('+'|'-')^ multiplicativeExpression
>>>>>>>>> {$additiveExpression.setType(Operator);})*
>>>>>>>>> ;
>>>>>>>>>
>>>>>>>>> in the parser grammar produces
>>>>>>>>>
>>>>>>>>> if ( state.backtracking==0 ) {
>>>>>>>>> $additiveExpression.setType(Operator);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> in the parser class.
>>>>>>>>>
>>>>>>>>> (I'm using 3.1b in case this makes a difference.)
>>>>>>>>>
>>>>>>>>> Cheers,
>>>>>>>>> Dimitrios
>>>>>>>>>
>>>>>>>>> Terence Parr wrote:
>>>>>>>>>>
>>>>>>>>>> Use $ not #
>>>>>>>>>> On Jun 6, 2008, at 6:27 AM, Dimitrios Kolovos wrote:
>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> In ANTLR2 I was able to change the type of the current AST like
>>>>>>>>>>> this:
>>>>>>>>>>>
>>>>>>>>>>> additiveExpression
>>>>>>>>>>> :    multiplicativeExpression ((PLUS^|MINUS^)
>>>>>>>>>>> multiplicativeExpression
>>>>>>>>>>> {#additiveExpression.setType(OPERATOR);})*
>>>>>>>>>>> ;
>>>>>>>>>>>
>>>>>>>>>>> but I haven't been able to find how to do the same in v3. Any
>>>>>>>>>>> hints?
>>>>>>>>>>>
>>>>>>>>>>> Cheers,
>>>>>>>>>>> Dimitrios
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
>>
>>
>