[antlr-interest] Tree grammar for 'zero or more' rewrite

[Ted Villalba]

Hi Ter,

I have to apologize, I created my original tree incorrectly, and probably
steered you wrong in your help.
It should have been:

0 terms:
               =
             /    \
          TAG   VALUE
              |        |
            to      TERM
                      |
                    foo

1 term:

               =
             /    \
          TAG   VALUE
             |        |
            to     OR
                  /     \
             TERM  VALUE
                 |          |
               foo     TERM
                           |
                         bar
2 terms:

                =
             /    \
          TAG  VALUE
             I        |
            to       OR
                  /     \
             TERM  VALUE
                 |          |
               foo     AND                           |
                        /     \
                    TERM  TERM
                       |          |
                     bar      duff

     Sorry. Probably made a difference in your suggestion for the first alt
for value_.

Thanks,
Ted

On 7/12/07, Ted Villalba <ted.villalba at gmail.com> wrote:
>
> Hi,
>
> Referring back to your instructions below, I have a couple of questions:
>
>
> > > value : value_ -> ^(VALUE value_) ;
> > >
> > > and rename value to value_:
> > >
> > > value   : terms ( operator^  terms )*
> > >
> >      | LPAREN! value RPAREN! ( operator^ value)* // i'll ignore as i
> > > don't know what you want
> > >      ;
> > >
> > > Also don't call value recursively in first alt.  That will create the
> > > wrong associativity for OR...it will do associativity you find with
> > > exponents.  Now you can use simple ^ operator.
> >
> >
> the issue with the new first alt is that it no longer accommodates  when
> the second operand is surrounded by PARENs, like : ...blah blah AND ( more
> stuff OR whatever).
>
>
>
> The second question I have is:
> How to define the tree grammar for rules and alts that have no rewrite
> specification. For instance:
>         LPAREN! value RPAREN! ( operator^ value)*
>
> Going back to reread the book, but at the moment, when there is a rewrite
> rule, it's more obvious to me, because I simply move it over to the tree
> grammar. When there's not, I'm not sure how to define the tree grammar for
> the alternates with inline ^ operators, or for that matter * operators.
>
> Thanks again,
> Ted
>
>
>
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