[antlr-interest] Island grammar in AntlrV3
ilia at obnovlenie.ru
Sun Sep 3 01:46:16 PDT 2006
Yes, but you parse island grammar at lexer-stage in that example.
And we find it at parsing-stage.
I guess its a matter of few lines to process this case correctly...
> have you seen the island grammar example in the examples-v3 tarball?
> On Sep 2, 2006, at 4:01 PM, David Holroyd wrote:
> > On Sat, Sep 02, 2006 at 11:09:32PM +0400, Ilia Kantor wrote:
> >> I have island grammar, that becomes known on parsing stage.
> >> How can I parse it with separate lexer/parser,
> >> adding result to common tree ?
> > I've also been wondering about this, but I don't have an answer yet.
> > I'm worried that by the time the parser has the chance to try and
> > fiddle
> > with the lexer, lookahead has consumed the input anyway. Maybe the
> > standard infrastructure can let the input character stream
> > 'backtrack'?
> > My specific use case is regular expression literals, e.g. I'd like
> > to be
> > able to handle,
> > r = / b; f = r/m; // regexp literal with 'm' flag
> > r = a / b; f = r/m; // two expr-statements involving division
> > It seems that the lexer needs context from the grammar in order to
> > tell
> > what to do on seeing '/'.
> > I've seen that the ECMAscript grammar on antlr.org sidesteps this
> > difficulty by dispensing with a lexer per se, and doing everything
> > in the
> > parser. This makes my brain itch. :)
> > Any clues?
> > ta,
> > dave
> > --
> > http://david.holroyd.me.uk/
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