[antlr-interest] Re: JavaTreeParser? What does it do?
lgcraymer
lgc at mail1.jpl.nasa.gov
Tue Apr 29 10:59:40 PDT 2003
Tree parsers do the "getFirstChild()" and "getNextSibling()" for
you as well as matching a tree pattern--the whole idea is to extend
the ANTLR parsing concept to trees. About the only case where you
might want to walk a tree without a tree parser is when the "Visitor"
pattern is appropriate.
--Loring
--- In antlr-interest at yahoogroups.com, "jw9315" <jw9315 at b...> wrote:
>
> Hi,
> yeah, sorry I did see that linkm but I'm new to this and didn't
quite
> understand. What I'm trying to do is build an interpreter for a
> *small* subset of the Java language. I ran the example in the Java
> grammars folder to give me a nice AST tree for any program I type in
> at the command line, and was planning on parsing and interpreting
the
> program using the method calls such as .getChild().
>
> What I was confused about is the fact that I call such as "AST myAST
> = r.getFirstChild();", but what is the difference between this and
> the line "JavaTreeParser tparse = new JavaTreeParser();". I can't
> understand what you can do differently with the two different
> commands! Sorry if this is a really stupid question but if there's a
> short answer that anyone's willing to give I would be glad to hear
it.
> Thanks,
> Jon
>
> --- In antlr-interest at yahoogroups.com, Terence Parr <parrt at j...>
> wrote:
> > Hi. Have you checked the faq entry that answers your question?
> >
> > http://www.jguru.com/faq/view.jsp?EID=818959
> >
> > It's called: What is a tree parser and why would I want to use
one?
> >
> > <snicker>
> >
> > Terence
> >
> > On Monday, April 28, 2003, at 10:17 AM, jw9315 wrote:
> >
> > > Hi,
> > > I'm a brand new ANTLR user. I'm using the AST tree it produces
to
> > > create an interpreter for a small subset of the Java programming
> > > language. I was looking at the Main.java file in the grammar
> examples
> > > directory, and one of the last lines says:
> > > '
> > > JavaTreeParser tparse = new JavaTreeParser();
> > > try
> > > {
> > > tparse.compilationUnit(t);
> > > System.err.println("successful walk of result
> > > AST for "+f);
> > > }
> > > catch (RecognitionException e) {
> > > System.err.println(e.getMessage());
> > > e.printStackTrace();
> > > }
> > > ' Could anyone tell me what this block does in the program, what
> is
> > > a JavaTreeParser?
> > > Thanks,
> > > Jon
> > >
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> > > http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> > --
> > Co-founder, http://www.jguru.com
> > Creator, ANTLR Parser Generator: http://www.antlr.org
> > Co-founder, http://www.peerscope.com link sharing, pure-n-simple
> > Lecturer in Comp. Sci., University of San Francisco
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