[antlr-interest] Re: Error recovery
lgcraymer
lgc at mail1.jpl.nasa.gov
Mon Apr 12 13:20:56 PDT 2004
--- In antlr-interest at yahoogroups.com, "jduquevieira" <jpdv at m...> wrote:
> --- In antlr-interest at yahoogroups.com, "lgcraymer" <lgc at m...> wrote:
> > What you really want to change is the input buffering. Check out
> > CharBuffer.java in the antlr directory and write an equivalent
> > (assuming that you are using Java--C++ and C# differ) that blocks
> on
> > interactive input at end of line rather than returning EOF.
> >
> > --Loring
>
>
> Hi Loring. Thanks for taking the time to answer.
>
> Anyway, I think that I didn't explain my self correctely.
> Imagine that the user writes:
> "2+*4)"
>
> As you can see, there are parenthesis missing (left) and a number
> (between the "+" and the "*").
Ouch! That's a tougher problem. You need to insert imaginary tokens (or AST nodes) wherever you are missing a token. There are
multiple interpretations possible since both extraneous and missing elements are possible. You are pretty much on your own, here. I
would suggest doing a web search on error recovery and user input--maybe you can find something that will help.
--Loring
>
> Even though the user as failed to write a correct statement, my
> editor has to be able to recover from it and show place holders
> where the missing characters were expected:
> "_2+_*4)"
>
> All of this graphically, of course. But, that point is already
> covered.
> All I have left to solve is the parser.
>
> Any ideas?
>
> Best regards.
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