Hello,
I have a problem with my grammar that I don't manage to solve and a
little help would really be greatful :o)
Here is the situation : I use Bison for a command interpreter. I deal
with variables (float values) and signals (object that contains
informations and a tab of float values that can be plotted).
Here is 2 examples of common use :
My_var = 3. + 1.
My_signal = 4. + My_other_signal
Mysignal = My_other_signal + 4.
Let's assume that My_var and My_signal are new identifiers, my problem
is that in the second example the command "Mysignal = 4." is recognized
by Bison as an integer variable assignment (with parsing error because
of "My_other_signal") while what should have been done is to recognize
that "4. + My_other_signal" is a signal (and process it) and then do a
signal assignment. In the third example, it works fine.
I don't manage to tell Bison that the priority is to process what is at
the right of the '=' before assigning the result using the good rule
* Here are the precedence and priority used :
%right '='
%left OPERATOR1 /* '+' '-' */
%left OPERATOR2 /* '*' '/' */
%left '(' ')'
%left UNARY /* for '-3' */
* Here are the rules used
base : /* empty */
| var_asgn
| signal_asgn
;
new_id_equal : IDENTIFIER '=' { $$ = $1; }
;
var_asgn : new_id_equal float_val { $$ = $2; }
;
signal_asgn : new_id_equal signal { $$ = $2;}
;
float_value : FLOAT_VALUE { $$ = $1; }
| float_value OPERATOR1 float_value { $$ = ... }
| float_value OPERATOR2 float_value { $$ = ... }
| '(' float_value ')' { $$ = $2; }
| OPERATOR1 float_value %prec UNARY { $$ = -$2; }
;
signal : '(' signal ')' { $$ = $2; }
| full_function_call { $$ = $1; }
| OPERATOR1 signal %prec UNARY { $$ = ... }
| signal OPERATOR1 signal { $$ = ... }
| signal OPERATOR2 signal { $$ = ... }
| signal OPERATOR1 float_value { $$ = ... }
| float_value OPERATOR1 signal { $$ = ... }
| signal OPERATOR2 float_value { $$ = ... }
| float_value OPERATOR2 signal { $$ = ... }
;
full_function_call : ...
;
Do you have any information that could help me ?
Best regards,
Julien
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