[antlr-interest] how to let parser control lexer state.

[David Holroyd]

On Fri, Apr 27, 2007 at 10:42:24AM -0700, Loring Craymer wrote:
> That's what semantic predicates (in the parser) are
> for--there are no lexical issues involved in this
> case.  You want to do the symbol table lookup and test
> in a predicate.

Here-docs are a lexing problem, I think -- content on subsequent lines
must not be interpreted with normal lexer rules until the document
terminator is seen..?

> --- femtowin1 <femtowin1 at gmail.com> wrote:
> 
> > Hi all, in antlr3, can parser control lexer state
> > and decide how lexer lexing? some grammar has
> > ambiguity
> > decided upon by parser knowledge.
> >   for ruby grammar <<
> > x << 1
> > test
> > 1
> > if x is a variable, then << is shift operator,
> > otherwise it is a heredoc. so lexing must know
> > from the symbol table whether x has been defined
> > beforehand. But current antlrv3 implementation,
> > lexer lexing to a constant token stream, and feed
> > it into parser, so can't achieve this effect.

-- 
http://david.holroyd.me.uk/