proc.h

来自「简单的编译词法分析 in c」· C头文件 代码 · 共 65 行

/*
  proc.h
 */

#define STKSIZ 100
char opstk[STKSIZ];
int opsp = 0;
#define PUSH(op) (opstk[opsp++] = op)
#define POP() (opstk[--opsp])
#define EMPTY() (opsp == 0)
#define PEEK() (!EMPTY() && opstk[opsp-1])

#define MAXLEN 200
char expr[MAXLEN];
int elen = 0;
#define EMIT(ch) (expr[elen++] = ch)

void procsym()
{
     char ch;
     switch (sym) {
     case '(':
	  PUSH('(');
	  break;
     case ')':
	  while ((ch = POP()) != '(')
	       EMIT(ch);
	  break;
     case '|':
	  if (PEEK() == '*' || PEEK() == '.')
	       EMIT('|');
	  else PUSH('|');
	  break;
     case '*':
	  if (EMPTY()) EMIT('*');
	  else PUSH('*');
	  break;
     default:
	  EMIT(sym);
	  break;
     }
}

void mkdot()
{
     if (PEEK() == '*')
	  EMIT('.');
     else PUSH('.');
}

void eflush()
{
     while ( !EMPTY() ) {
	  EMIT(POP());
     }
}

#undef STKSIZ
#undef PUSH
#undef POP
#undef EMPTY
#undef PEEK
#undef MAXLEN
#undef EMIT