Hello, [apologies if this is a common question, I didn't find any FAQ for this list]
I am using Bison (v1.24, a windows port I found on the web; I'm not on linux) for a simple command-line interpreter of my own experimental language. The parser actions are used to recursively build up a kind of syntax tree, so they allocate various objects along the way. This works fine, except when there are parse errors; in which case I need to intercept and deallocate whatever objects have been allocated so far, to avoid memory leaks. To do this cleanup I need to find the thing produced by the last reduction before the error. I first thought I could use yylval inside the yyerror() routine for this, but I constantly find that yylval is empty (null) when entering yyerror(). So how do I access the value of the last reduction (i.e. the last thing assigned to $$) ?? By the way, yylval is null also after successful parsing. I thought this was strange too, from what I gathered from the Bison docs it should contain the $$ result at all the time? I got around that by inserting a "top level" rule that simply copies $$ to a different variable prior to accepting, but it seems like a weird work-around ... ? Thanks for any help! Best, Roland Nilsson Linköping, Sweden _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
