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(bison.info)Mfcalc Rules

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Grammar Rules for `mfcalc'
--------------------------

   Here are the grammar rules for the multi-function calculator.  Most
of them are copied directly from `calc'; three rules, those which
mention `VAR' or `FNCT', are new.

     input:   /* empty */
             | input line
     ;
     
     line:
               '\n'
             | exp '\n'   { printf ("\t%.10g\n", $1); }
             | error '\n' { yyerrok;                  }
     ;
     
     exp:      NUM                { $$ = $1;                         }
             | VAR                { $$ = $1->value.var;              }
             | VAR '=' exp        { $$ = $3; $1->value.var = $3;     }
             | FNCT '(' exp ')'   { $$ = (*($1->value.fnctptr))($3); }
             | exp '+' exp        { $$ = $1 + $3;                    }
             | exp '-' exp        { $$ = $1 - $3;                    }
             | exp '*' exp        { $$ = $1 * $3;                    }
             | exp '/' exp        { $$ = $1 / $3;                    }
             | '-' exp  %prec NEG { $$ = -$2;                        }
             | exp '^' exp        { $$ = pow ($1, $3);               }
             | '(' exp ')'        { $$ = $2;                         }
     ;
     /* End of grammar */
     %%