Hi joe, add another rule to exp, eg
exp: NUMBER { $$ = convert_str_to_int($1); } | /* you rules */ otherwise exp cannot be derived as all the other rules involve exp itself. -tomas On Tue, 2009-08-04 at 22:12 +0100, j...@garveydesign.com wrote: > Thanks for your help. > I have attached the latest listing of the program in question. When I run > Bison now, then the messages I get from that are... > parse.y: warning: 8 useless nonterminals and 30 useless rules > parse.y:52.1-7: fatal error: start symbol grammar does not derive any > sentence > > I believe that The particular code it refers to is... > %% > grammar: domains > constants > predicates > ; > > My intention is that it reads a set of domains... > typically each one is to a line of a format... > D0 11 0 10 // domainName, number_of_values, floor_value, ceil_value > ... > Then reads a set of constants... > typically each one to a line of a format... > X0 D0 9 > > Then reads and processes a set of predicates, each one to a line, which > may appear as... > or(lt(mul(X0,X1),X2),ge(abs(sub(X3,X4)),X5)) > > However, I have no precedent or pro-forma for such as 'grammar' above. I > think that the domains constants predicates sequence I've written will > read all the > domains, then all the constants then all the predicates without allowing > any regression through any of them (eg a domain in the constants). > > That the start symbol 'grammar' cannot derive any sentence only suggests > to me that the grammar high level nonTerminal cannot access it's > subsidiary terminals and non-terminals, but the exact cause is not yet > clear to me. > > The classic example such as p75 of lex & yacc...[1995 Levine et al] > statement_list: statement '\n' > statement_list statement '\n' > ; > ...doesn't shed much light on my codes attached below, where I must read a > group of domains, followed by a group of constants, followed by a group of > predicates. > > _______________________________________________ > help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison