[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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