[antlr-interest] Layout processing

[Daniel Shane]

Hi all,

I'm rather new to ANTLR processing and I was wondering if ANTLR could solve 
my problem.

The language that I am trying to parse contains layout characters (mainly 
whitespaces). As I understand in ANTLR, these layout characters should be 
handled in the lexer and ignored at the source. The problem is that I would 
like to keep them in the parse tree without having to sparkle them all over 
the grammar.

Would it be possible to override LA() and match() to be able to skip 
(ignore) layout tokens while at the same time keeping them in the parse 
tree?

I know that stated this way, it is ambigous, how can ANTLR, without further 
information, know where to place the WS in the parse tree? In my example, I 
would like WS to be "factored" out of rules as much as possible so that they 
are only present in the body of a rule, not at the start nor at the end of 
them.

State that way, there is only one place for every WS present in the instance 
to parse. Not knowing that much about ANTLR, is there a way to automagically 
override a certain function to obtain this behaviour?

My only alternative is to sprinkle (WS)? elements nearly everywhere in the 
grammar... Certainly there is a better way to do this since this would beef 
up my grammar by 50% (in characters) and also give me the headache of a 
lifetime figuring out the right k because of all the optional WS that could 
happen.

Thanks in advance!
Daniel Shane

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