I have started to learn ANTLR and have both the 2007 book “The Definitive ANTLR Reference” and ANTLRWorks (an interactive tool for creating grammars). And, being that sort of person, I started at Chapter 3. (“A quick tour for the impatient”).
It’s a fairly painful process especially as some errors are rather impenetrable (e.g. ANTLR: "missing attribute access on rule scope" problem which just means to me “you got something wrong”). Also I have some very simple grammars (3-4 productions only) and simple input (2 lines) which when run give “OutOfMemory” error.
The ANTLR site is useful but somewhat fragmented and some SO users have commented (https://stackoverflow.com/questions/278480/good-tutorial-for-antlr) that the book and the tutorials expect a high entry level. I’ve been reluctant to approach the ANTLR discussion list because of this.
LATER We are beginning to get to grips with it. It would be useful to have simple reliable examples that could be gently expanded. It’s certainly worth mastering as we have remodelled quite a lot of our thinking based on ANTLR.
One problem is that ANTLR V3 has signifcant changes from V2. One answer on SO (and on the ANTLR pages) refered to a V2 syntax that is no longer available.
Some of the ANTLR questions on SO have helped me a lot, but finding them is a bit ad hoc. So I’d like to know how SO users can help to make the learning process less painful. (If you refer to the reference book it would be useful to point to particular pages).
EDIT. @duffymo and @JamesAnderson have confirmed that ANTLR is hard work – largely because parsers are difficult. (FWIW I have been through LEX/YACC, etc. and there’s no doubt that ANTLR is more powerful and easier to work with.) I think it would still be useful to have areas where it’s possible to avoid fouling up such as:
- ensure correct capitalisation of variable names
- add package name to lexer as well as parser
- take care over order of rules as it affects precedence
and more of these sort would be useful.
I agree – ANTLR is not for the faint of heart. It does expect a high entry level, because grammars and parsers are not trivial.
With that said, here are a few suggestions:
ANTLR won’t be easy to master. The book is good, but dense. The error messages are cryptic, as you’ve noted. I’d be surprised if anyone here could make it easy.