[antlr-interest] new action syntax proposal
Jim Idle
jimi at temporal-wave.com
Sat Jul 14 18:38:10 PDT 2007
The only slight issue I see with that is that in some target languages
the second { would sometimes be meaningful:
r:
FRED
{
{ int a; ...}
}
Though this is a minor barrier, perhaps it can be avoided by using
another character as otherwise people may specify a backtrack executing
action without realizing it.
Perhaps:
{<
>}
(you can read the < as backtrack I guess:
I suspect though that all such sequences offer some clash with targets
;-)
Jim
> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Terence Parr
> Sent: Friday, July 13, 2007 4:40 PM
> To: antlr-interest Interest
> Subject: [antlr-interest] new action syntax proposal
>
> Hi,
>
> Actions are not executed during backtracking as we cannot undo
> stateful actions. The problem is that some semantic predicates that
> test, for example, the symbol table rely on actions updating the
> symbol table during backtracking. I propose {...} stay same as an
> action but {{...}} (double curlies) implies always execute even when
> backtracking.
>
> Counterproposals?
>
> Ter
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