machine.c

简单的编译词法分析 in c

/*
  machine.c
 */

#include "machine.h"
#include <string.h>
#include <assert.h>

extern Mach finm;

#define MAXST 100
char tbl[MAXST][MAXST];
int stcnt = 0;

#define EP '$'
#include<stdio.h>
void init_tbl()
{
  memset((void *)tbl, 0, MAXST*MAXST*sizeof(char));//??assert ,what?
	
}

stat new_st()//开始一个新的状态

{
  if (!stcnt) init_tbl();//如果没有到栈底

  stcnt++;

  printf("new stat: stat%d\n", stcnt);

  return stcnt;
}

void addtran(stat s, stat z, char ch)
{
  printf("stat%d ---> stat%d on %c\n", s, z, ch);
  assert( s <= stcnt && z <= stcnt );//如果表达式为0，assert将会打印打印一条消息
  tbl[s][z] = ch;
}

int run()
{
  int csts[MAXST]; /* current states */
  int nsts[MAXST]; /* next states */
  int c;
  int i, j;
  int epclose = 0;
  /* clear current states */
  memset((void *)csts, 0, MAXST*sizeof(stat));
  csts[finm.h] = 1;

  while ((c = getchar()) != '\n') {

    /* clear current states */    
    memset((void *)nsts, 0, MAXST*sizeof(stat));

    
    while (!epclose) {

      epclose = 1;

      /* get all possible next states */
      
      for (i = 1; i < MAXST; i++) {
	if (!csts[i]) continue;
	for (j = 1; j < MAXST; j++) {
	  if ( tbl[i][j] == c || tbl[i][j] == '$' )
	    if (nsts[j] != 1) {
	      nsts[j] = 1;
	      epclose = 0;
	    }
	}
      }

      /* move nsts to csts */
      memmove(csts, nsts, MAXST*sizeof(stat));
    }
  }

  /* accept ? */
  if (csts[finm.t] == 1)
    printf("Accepted!");
  else
    printf("Refused!");
  return 0;

}

#undef MAXST