Basically, I want to derive information from it. For example, if I got a matrix like [[1,2],[3,4]], I want to find the dimensions of it. The thing is, taht I had already a pretty good function for doing this, when I had manipulating the expression without bison. now with bison, if I want to the same thing, i have to make it from the start. I will try to do it just with bison, but if it gets too complicated, I might use my old function to find dimensions and then do whatever I want with bison.
Stratis Laurence Finston wrote: > > > On Fri, 28 Nov 2008, sgaurelius wrote: > >> Flex scanner has previously analyzed the string and extracted the tokens. >> However, if I want the text that corresponds to this expression, for >> example >> the "(1+2)" and not just the tokens, what should I do ? Is there some >> solution ? > > Save `yytext' somewhere "persistent". `yytext' is available in the > actions of your scanner. You can save it in a data member of an object > that you pass as a parameter to `yylex'. If you use Flex, you can pass a > parameter of a certain type (I'd have to look up what it's called) and > declare an object of a type of your choice to be a data member of this > object. I use this to carry around information that needs to be available > within my scanner and parser rules, and outside them. This is a > thread-safe approach. > > Alternatively, you could pass the strings back to `yyparse' as the > semantic values of the tokens, _unless_ you need the semantic values to be > numeric values or something else. This might be easier, because you > wouldn't have to keep track of which string is associated with a given > token. If you chose this approach, you might have to convert strings to > numbers in your parser rules, which isn't very difficult. > > There are probably other approaches, but these are the ones that occur to > me off the top of my head. However, I can't think of any reason why I > would want to keep the strings. > > Laurence Finston > > > _______________________________________________ > help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison > > -- View this message in context: http://www.nabble.com/How-to-get-the-text-corresponding-to-a-bison-rule-tp20732674p20734369.html Sent from the Gnu - Bison - Help mailing list archive at Nabble.com. _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison