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%{
#include <stdio.h>
#include <stdlib.h>
extern int yylex();
extern int yyparse();
extern FILE* yyin;
void yyerror(const char* s);
%}
%union {
int ival;
float fval;
}
%token<ival> T_INT
%token<fval> T_FLOAT
%token T_PLUS T_MINUS T_MULTIPLY T_DIVIDE T_LEFT T_RIGHT
%token T_NEWLINE T_QUIT
%left T_PLUS T_MINUS
%left T_MULTIPLY T_DIVIDE
%type<ival> expression
%type<fval> mixed_expression
%start calculation
%%
calculation:
| calculation line
;
line: T_NEWLINE
| mixed_expression T_NEWLINE { printf("\tResult: %f\n", $1);}
| expression T_NEWLINE { printf("\tResult: %i\n", $1); }
| T_QUIT T_NEWLINE { printf("bye!\n"); exit(0); }
;
mixed_expression: T_FLOAT { $$ = $1; }
| mixed_expression T_PLUS mixed_expression { $$ = $1 + $3; }
| mixed_expression T_MINUS mixed_expression { $$ = $1 - $3; }
| mixed_expression T_MULTIPLY mixed_expression { $$ = $1 * $3; }
| mixed_expression T_DIVIDE mixed_expression { $$ = $1 / $3; }
| T_LEFT mixed_expression T_RIGHT { $$ = $2; }
| expression T_PLUS mixed_expression { $$ = $1 + $3; }
| expression T_MINUS mixed_expression { $$ = $1 - $3; }
| expression T_MULTIPLY mixed_expression { $$ = $1 * $3; }
| expression T_DIVIDE mixed_expression { $$ = $1 / $3; }
| mixed_expression T_PLUS expression { $$ = $1 + $3; }
| mixed_expression T_MINUS expression { $$ = $1 - $3; }
| mixed_expression T_MULTIPLY expression { $$ = $1 * $3; }
| mixed_expression T_DIVIDE expression { $$ = $1 / $3; }
| expression T_DIVIDE expression { $$ = $1 / (float)$3; }
;
expression: T_INT { $$ = $1; }
| expression T_PLUS expression { $$ = $1 + $3; }
| expression T_MINUS expression { $$ = $1 - $3; }
| expression T_MULTIPLY expression { $$ = $1 * $3; }
| T_LEFT expression T_RIGHT { $$ = $2; }
;
%%
int main() {
yyin = stdin;
do {
yyparse();
} while(!feof(yyin));
return 0;
}
void yyerror(const char* s) {
fprintf(stderr, "Parse error: %s\n", s);
exit(1);
}
|
