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gzdoom/tools/re2c/examples/001_upn_calculator/calc_004.re
2016-02-06 20:58:35 -06:00

78 lines
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C++

/* re2c lesson 001_upn_calculator, calc_004, (c) M. Boerger 2006 - 2007 */
/*!ignore:re2c
- making use of definitions
. We provide complex rules as definitions. We can even have definitions made
up from other definitions. And we could also use definitions as part of
rules and not only as full rules as shown in this lesson.
- showing the tokens
. re2c does not store the beginning of a token on its own but we can easily
do this by providing variable, in our case t, that is set to YYCURSOR on
every loop. If we were not using a loop here the token, we could have used
s instead of a new variable instead.
. As we use the token for an output function that requires a terminating zero
we copy the token. Alternatively we could store the end of the token, then
replace it with a zero character and replace it after the token has been
used. However that approach is not always acceptable.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
char * tokendup(const char *t, const char *l)
{
size_t n = l -t + 1;
char *r = (char*)malloc(n);
memmove(r, t, n-1);
r[n] = '\0';
return r;
}
int scan(char *s, int l)
{
char *p = s;
char *q = 0;
char *t;
#define YYCTYPE char
#define YYCURSOR p
#define YYLIMIT (s+l+2)
#define YYMARKER q
#define YYFILL(n) { printf("OOD\n"); return 2; }
for(;;)
{
t = p;
/*!re2c
re2c:indent:top = 2;
DIGIT = [0-9] ;
OCT = "0" DIGIT+ ;
INT = "0" | ( [1-9] DIGIT* ) ;
OCT { t = tokendup(t, p); printf("Oct: %s\n", t); free(t); continue; }
INT { t = tokendup(t, p); printf("Num: %s\n", t); free(t); continue; }
"+" { printf("+\n"); continue; }
"-" { printf("+\n"); continue; }
"\000" { printf("EOF\n"); return 0; }
[^] { printf("ERR\n"); return 1; }
*/
}
return 0;
}
int main(int argc, char **argv)
{
if (argc > 1)
{
return scan(argv[1], strlen(argv[1]));
}
else
{
fprintf(stderr, "%s <expr>\n", argv[0]);
return 0;
}
}