"Walter Bright" <newshou...@digitalmars.com> wrote in message news:ia0cfv$22k...@digitalmars.com... > Nick Sabalausky wrote: >> Would Walter & co be interested in this? If not, I won't bother, but if >> so, then I may give it a shot. > > The problem is I never have used parser/lexer generators, so I am not > really in a good position to review it.
Understandable. FWIW though, Goldie isn't really lexer/parse generator per se. Traditional lexer/parser generators like lex/yacc or ANTLR will actually generate the source code for a lexer or parser. Goldie just has a single lexer and parser, both already pre-written. They're just completely data-driven: Compared to the generators, Goldie's lexer is more like a general regex engine that simultaneously matches against multiple pre-compiled "regexes". By pre-compiled, I mean turned into a DFA - which is currently done by a separate non-source-available tool I didn't write, but I'm going to be writing my own version soon. By "regexes", I mean they're functionally regexes, but they're written in a much easier-to-read syntax than the typical PCRE. Goldie's parser is really just a rather typical (from what I understand) LALR parser. I don't know how much you know about LALR's, but the parser itself is naturally grammar-independent (at least as described in CS texts). Using an LALR involves converting the grammar completely into a table of states and lookaheads (single-token lookahead; unlike LL, any more than that is never really needed), and then the actual parser is directed entirely by that table (much like how regexes are converted to data, ie DFA, and then processed generically), so it's completely grammar-independent. And of, course, the actual lexer and parser can be optimized/rewritten/whatever with minimal impact on everything else. If anyone's interested, further details are here(1): http://www.devincook.com/goldparser/ Goldie does have optional code-generation capabilities, but it's entirely for the sake of providing a better statically-checked API tailored to your grammar (ex: to use D's type system to ensure at compile-time, instead of run-time, that token names are valid and that BNF rules you reference actually exist). It doesn't actually affect the lexer/parser in any non-trivial way. (1): By that site's terminology, Goldie would technically be a "GOLD Engine", plus some additional tools. But, my current work on Goldie will cut that actual "GOLD Parser Builder" program completely out-of-the-loop (but it will still maintain compatibility with it for anyone who wants to use it).
