evil.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>

int s[1024],i=0,a,b,m[4096];
char *d[256],e;

#define X(x)   (i>0?(x)=s[--i]:E("SU"))
#define Y      (X(b),X(a))
#define Z(x)   (i<1024?s[i++]=(x):E("SO"))
#define W(o)   (Y,Z(a o b))
#define V(o)   C(o)?W(o):
#define E(x)   (fprintf(stderr,x"\n"),abort(),0)
#define P      printf
#define S      strcmp
#define K      strlen
#define A      atoi
#define L      assert
#define B      abort
#define D(x)   isdigit(*x)
#define U(x)   strdup(x)
#define C(x)   !S(w,#x)
#define T(x)   strtok_s(x," \t\n",&c)

char *q(char *n) {
    for(char **j=d;*j;j+=2) if(!S(n,*j)) return j[1];
    return 0;
}

void r(char* n, const char *t) {
    char *c,z=1,y=1,*o,l[256],*w=(strncpy(l,t,256),l[255]=0,T(l));
    do  V(+)V(-)V(*)V(/)
        C(;)?z=0:
        C(@)?z=1:
        C(nz)?X(a),z=!!a:
        C(drop)?X(a):
        C(.)?X(a),P("%c",a):
        C(read)?X(a),a=m[a],Z(b):
        C(write)?Y,m[a]=b:
        C(swap)?Y,Z(a),Z(b):
        C(dup)?X(a),Z(a),Z(a):
        C(:)?w=T(NULL),d[e*2]=U(w),d[e*2+1]=U(c),e+=1,w=T(strchr(c,';')),0:
        D(w)?Z(A(w)):
        (o=q(w),(o?0:E("?")),(S(n,w)?(r(w,o),0):(strncpy(l,t,256),l[255]=0,w=T(l),y=0)),0);
    while (z&&(y?w=T(NULL):(y=1,w)));
}

int main(int argc, char **argv) {
    char *l;
    do l=fgets(malloc(80), 80, stdin), l?(r("", l), P("ok.\n")):0; while (l);
    return 0;
}