Christopher Diggins wrote:
Would you please post the grammar productions you used for Spirit? Would you consider testing the yard parser as well, http://yard-parser.sf.net ? Are there other advantages of your tool over Flex, other than providing a nice interface to Spirit?
The grammar for Spirit was (in a slightly cut down form): keyword = str_p( "Group" ) | str_p( "Separator" ) | //etc.; comment = lexeme_d[ ch_p( '#' ) >> * ( ~chset_p( "\n\r" ) ) >> chset_p( "\n\r" ) ]; stringLiteral = lexeme_d[ ch_p( '\"' ) >> * ( ~chset_p( "\"\n\r" ) ) >> chset_p( "\"\n\r" ) ]; word = lexeme_d[ ( alpha_p | ch_p( '_' ) ) >> * ( alnum_p | ch_p( '_' ) ) ]; floatNum = real_p; vrml = *( keyword | comment | stringLiteral | word | floatNum ); I've cut down the keywords because there are over 60 of them. I would be interested to know if there was any obvious ways to optimise the Spirit parser. Regarding writing a comparitive test for YARD, I will certainly consider it, although I have no experience of using YARD. I've written quite a lot of flex/bison parsers, written a number of Spirit based parsers, and hand coded a number in my time, but I would need to spend a little time learning the YARD framework first. There are a number of advantages over Flex (including a nice interface to Spirit). The key ones are: 1) An extensible object oriented approach to writing the entire system. This can be very useful if you want to handle something like say the parsing of a filename in the lexer. You can simply write a new token type that will split the incoming filename into path, extension, name, etc. This can massively simplify the production of a final parser - allowing you to deal with grammar issues at that stage. 2) DFAs can be created at run-time, or eventually compile-time. 3) The code is considerably less obfuscated than the code produced by flex. Don't get me wrong, I like flex a lot, but the pre-processor directives, and look-up tables in the generated code are pretty unreadable IMHO. Dave Handley