cvm.c

来自「压缩包里面的都是精致的基本C语言小程序」· C语言 代码 · 共 88 行

#include <stdio.h>
#include "../lib/error.h"
#include "../lib/hash.h"
#include "../lib/nat.h"
#include "../lib/mystdlib.h"
#include "../lib/linkedList.h"
#include "store.h"
#include "cvm.h"

nat cvmExp (store st, exp e)
{
  switch (e->kind)
  {
    case ADD :
    {
      nat n1 = cvmExp (st, (e->u).binop.e1);
      nat n2 = cvmExp (st, (e->u).binop.e2);
      nat n = natAdd (n1, n2);
      return n;
    }
    case SUB : 
    {
      nat n1 = cvmExp (st, (e->u).binop.e1);
      nat n2 = cvmExp (st, (e->u).binop.e2);
      nat n = natSub (n1, n2);
      return n;
    }
    case TIMES : 
    {
      nat n1 = cvmExp (st, (e->u).binop.e1);
      nat n2 = cvmExp (st, (e->u).binop.e2);
      nat n = natTimes (n1, n2);
      return n;
    }
    case ID : 
    {
      nat n = storeLookup (st, (e->u).id);
      return n;
    }
    case NUM : 
    {
      return (newNat ((e->u).i));
    }
    default: return (newNat (0));
  }
}

void cvmStm (store st, stm s)
{
  switch (s->kind)
  {
    case ASSIGN:
      {
        nat n = cvmExp (st, (s->u).a.e);
        storeUpdate (st, (s->u).a.id, n);
        break;
      }
    case PRINT:
      {        
        nat n = cvmExp (st, (s->u).print);
        natOutput (n);
        printf ("\n");
        break;
      }
    default:
      {
        error ("no this case\n");
        break;
      }
  }
}

void cvmProg (prog p)
{
  printf ("\nCVM starts:\n");
  linkedList l = linkedListGetFirst (p->stms);
  store st = newStore ();    
  while (l)
  {
    cvmStm (st, l->data);
    l = l->next;
  }  
  printf ("\nCVM halts\n");
  return;
}