Re: Context sensitive scanner ?

Albert Theo Hofkamp wrote:


          ......... If I would
> introduce states in the scanner such that the scanner would return
> only the `right' tokens, and the control of the state is done from
> within yacc, then I consider the moment when the parser executes the
> change of state as tricky.


> I am asking for a scanner which tries to do interpretation within
> the limits of what the parser expects. In other words, when the parser
> doesn't want a real, and the scanner gets a real as input, it will not
> return a real, but 2 integer numbers seperated by a dot.


There is another solution. (One I have not seen mentioned yet) Put a
function between lexer and parser that understands what the parser
expects, and has rules it can apply to modify the token stream. I have
done this to be able to use keywords as identifiers where there can be
no ambiguity. If you use bison I can even give you the code to
implement a beast like this. I don't know how easy this is for other
generators, but I think it must be possible (The generated code
knows...) .


Mark.


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