[antlr-interest] Re: Exception issues
Eric Mahurin
eric_mahurin at yahoo.com
Tue Aug 24 09:06:02 PDT 2004
I just figured out a partial workaround for the SemanticException. If
you have a semantic predicate not used to qualify an alternative:
{condition}?
just change this to:
( {condition}? | {false}? )
This makes it throw NoViableAltException instead which does have line
number info. Unfortunately, the message isn't useful - but the
line/column numbers are right.
It looks like the best solution is to try to move all of the semantic
predicates to be qualifiers on alternatives (or loops?) wherever possible.
Eric
--- In antlr-interest at yahoogroups.com, "Eric Mahurin"
<eric_mahurin at y...> wrote:
> Here are a few things I don't know how to resolve with the current
> antlr code with regard to exceptions:
>
> 1. SemanticException is constructed without any line, column, or
> filename. Why? It is not a very useful message - especially to the
> end-user that sees an expression with internal variables.
>
> 2. Ability to override the exception classes used for exception
> construction. In my case, I have include files so that the filename
> is not constant. I have another means of finding the filename (lookup
> table - ignores lexer/parser filename) and would like to use exception
> classes that use this method.
>
> Eric
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