Hi,
I would like to create a parser that reads the following input:
a = 1; b = 2; c = 3; d = 0;
y = a + b * c + d;
And outputs:
temp1 = b * c;
temp1 = 6;
temp2 = temp1 + d;
y = a + temp2;
y = 7;
I reviewed the bison manual and played with example three "mfcalc" from chapter
two. I copy the relevant part here, line numbers are added for convenience.
Obviously i need to define a counter that count the number of basic operations
( '+', '*' ) and use the number to identify the correct temp variable (temp1,
temp2, ...)
I need an action for the non-terminal expression (exp '+' exp), this action
should print (temp# = exp + exp;). Also, i need to find the result ($$ = $1 +
$3;). First, i added line 8 and received (error: invalid type argument of
`->') as a compilation error.
Next i added line 3 and line 11. The result was as "expected" postorder
expression. Please advise??
1: exp: NUM { $$ = $1; }
2: | VAR { $$ = $1->value.var;
3: printf("%s",$1->name);
4: }
5: | VAR '=' exp { $$ = $3; $1->value.var = $3; }
6: | FNCT '(' exp ')' { $$ = (*($1->value.fnctptr))($3); }
7: | exp '+' exp {
8: printf("temp%d = %s + %s",
temp_no, $1->name, $3->name);
9: $$ = $1 + $3;
10: printf("+");
11: temp_no ++;
12: }
Regards,
Abed
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