[antlr-interest] Re: upper, lower case for tokens, rule names
lgcraymer
lgc at mail1.jpl.nasa.gov
Fri Jul 18 11:29:12 PDT 2003
Ter--
I wrote this once, had yahoo throw me into the ether. I prefer the
current approach, not only for visual effect (which is pretty
important--highlighting is not an option for black-and-white text) but
for catching rules moved from one type of grammar (lexer, parser, tree
walker) to another. In the current scheme, moving a lexer rule is a
clear error as is moving a parser/treewalker rule into a lexer.
Parser and treewalker rules are handled by indeterminacy warnings when
moving parser rule to treewalker, and by finding an unexpected "#(" in
a parser grammar. [I point out that it is occasionally correct to
move rules and edit them to fit--that's a "feature" of being able to
parse in the lexer.]
I expect that the current distinction is also a help in a classroom
situation--it does clearly distinguish tokens from parser rule
references, and that has to help those unfamiliar with language
translation concepts.
--Loring
--- In antlr-interest at yahoogroups.com, Terence Parr <parrt at c...>
wrote:
>
> On Friday, July 18, 2003, at 10:40 AM, mzukowski at y... wrote:
>
> > It is nice to be able to distinguish tokens from rule names
visually,
> > mainly
> > because tree operators function differently on tokens vs rules.
As
> > long as
> > a syntax highlighter could figure it out pretty easily then it's
ok
> > with me.
>
> True. Also, some people I know use a special char to indicate
instance
> variable etc... perhaps some people would choose a special char or
> other pattern for token names like tkIdentifier, tkDecl, etc... or
> rProgram, rExpr, rAtom.
>
> Terence
> --
> Professor Comp. Sci., University of San Francisco
> Creator, ANTLR Parser Generator, http://www.antlr.org
> Co-founder, http://www.jguru.com
> Co-founder, http://www.knowspam.net enjoy email again!
> Co-founder, http://www.peerscope.com pure link sharing
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