[antlr-interest] Q: move from v2 to v3 parser grammar. Rewrite tree rule

[Jim Idle]

It is a trade off, as you guess. The features that come with v3 demanded
some changes and sometimes you have to lose a few conveniences. The
lexer/token changes were driven by performance for instance, whereby
copying text in to the token whether you were going to use it or not was a
performance hit.

You will probably see a few other things that may 'annoy' you at first,
but they are changes for good reason :)

Jim

> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Ruslan Zasukhin
> Sent: Wednesday, March 23, 2011 5:41 AM
> To: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] Q: move from v2 to v3 parser grammar.
> Rewrite tree rule
>
> On 3/23/11 1:54 AM, "Jim Idle" <jimi at temporal-wave.com> wrote:
>
> Hi Jim,
>
> > You can do it the same way in v3, but when you generate the code,
> > ANTLR will make up token names and you won't be able to write a good
> > error display routine/handler because you won't know the tokens. You
> > will just have T23 or something like that, and then you can't do
> > anything interesting. So, you don't HAVE to, but it is neater when
> you
> > come to do certain things.
>
> Aha, I see.
> Yes we have see that T23 a lots in generated code ..
>
>
> Interesting ... In v2 names of tokens was shown correctly Right?
>
>
> In v3 probably was some changes in architecture, Which prevent from
> this nice automatic feature ..
>
>
> Hmm. Actually it is not good, when a newer version loose nice features.
> :-)
>
> Again, thank you very much Jim for points.
>
>
>
> ==========
> Before click SEND button have come strange [and OPTIONAL] question to
> mind.
>
> If v3 was designed to support old AST operators ^ !
> And new re-write rules (ok for new)
>
> But why was trashed feature of  ## = (IMAGE_TOKEN, ##) ?
>     picture is broken.
>     two operators self cannot resolve all tasks ..
>
>
> If it was not touched, then porting was much easier I think.
>
> Or I do not see big idea behind of this step?
>
>
> --
> Best regards,
>
> Ruslan Zasukhin
> VP Engineering and New Technology
> Paradigma Software, Inc
>
> Valentina - Joining Worlds of Information http://www.paradigmasoft.com
>
> [I feel the need: the need for speed]
>
>
>
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