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|
%{
#define YYSTYPE double
%}
%token NUMBER
%left '+' '-'
%left '*' '/'
%left UNMIN
%%
list: /* ε */
| list '\n'
| list expr '\n' { print("\t%.8g\n", $2); }
;
expr: NUMBER
| '-' expr %prec UNMIN { $$ = -$2; }
| expr '+' expr { $$ = $1 + $3; }
| expr '-' expr { $$ = $1 - $3; }
| expr '*' expr { $$ = $1 * $3; }
| expr '/' expr { $$ = $1 / $3; }
| expr '%' expr { $$ = fmod($1, $3); }
| expr '(' expr ')' { $$ = $1 * $3; }
| '(' expr ')' { $$ = $2; }
;
%%
#include <u.h>
#include <libc.h>
#include <ctype.h>
#include <bio.h>
Biobuf *bin;
int lineno;
int prompt;
int yyparse(void);
void
yyerror(char *msg)
{
fprint(2, "%s at line %d\n", msg, lineno);
}
int
yylex(void)
{
int c;
if(prompt){
print("%d: ", lineno);
prompt--;
}
while((c = Bgetc(bin)) == ' ' || c == '\t')
;
if(c == '.' || isdigit(c)){
Bungetc(bin);
Bgetd(bin, &yylval);
return NUMBER;
}
if(c == '\n'){
lineno++;
prompt++;
}
return c;
}
void
usage(void)
{
fprint(2, "usage: %s\n", argv0);
exits("usage");
}
void
main(int argc, char *argv[])
{
ARGBEGIN{
default: usage();
}ARGEND;
if(argc > 0)
usage();
bin = Bfdopen(0, OREAD);
if(bin == nil)
sysfatal("Bfdopen: %r");
lineno++;
prompt++;
yyparse();
Bterm(bin);
exits(0);
}
|
