学步园

《C语言接口与实现》书中P235示例，源码在：

#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "include/stack.h"
#include "include/ap.h"
#include "include/fmt.h"

#pragma comment(lib, "libcii.lib")


Stack_T sp;
AP_T pop(void) 
{
	if (!Stack_empty(sp))
		return Stack_pop(sp);
	else {
		Fmt_fprint(stderr, "?stack underflow\n");
		return AP_new(0);
	}
}


int main(int argc, char *argv[])
{
	int c;
	sp = Stack_new();
	Fmt_register('D', AP_fmt);
	while ((c = getchar()) != EOF)
		switch (c)
		{
			case ' ': case '\t': case '\n': case '\f': case '\r':
				break;

			case '0': case '1': case '2': case '3': case '4':
			case '5': case '6': case '7': case '8': case '9': 
			{
				char buf[512];
				{
					int i = 0;
					for ( ; c != EOF && isdigit(c); c = getchar(), i++)
						if (i < (int)sizeof (buf) - 1)
							buf[i] = c;
						if (i > (int)sizeof (buf) - 1) {
							i = (int)sizeof (buf) - 1;
							Fmt_fprint(stderr,
								"?integer constant exceeds %d digits\n", i);
						}
						buf[i] = 0;
						if (c != EOF)
							ungetc(c, stdin);
				}
				Stack_push(sp, AP_fromstr(buf, 10, NULL));
				break;
			}
		case '+': 
			{
				AP_T y = pop(), x = pop();
				Stack_push(sp, AP_add(x, y));
				AP_free(&x);
				AP_free(&y);
				break;
			}
		case '-': 
			{
				AP_T y = pop(), x = pop();
				Stack_push(sp, AP_sub(x, y));
				AP_free(&x);
				AP_free(&y);
				break;
			}
		case '*': {
			AP_T y = pop(), x = pop();
			Stack_push(sp, AP_mul(x, y));
			AP_free(&x);
			AP_free(&y);
			break;
				  }
		case '/': 
			{
				AP_T y = pop(), x = pop();
				if (AP_cmpi(y, 0) == 0) {
					Fmt_fprint(stderr, "?/ by 0\n");
					Stack_push(sp, AP_new(0));
				} else
					Stack_push(sp, AP_div(x, y));
				AP_free(&x);
				AP_free(&y);
				break;
			}
		case '%': 
			{
				AP_T y = pop(), x = pop();
				if (AP_cmpi(y, 0) == 0) {
					Fmt_fprint(stderr, "?%% by 0\n");
					Stack_push(sp, AP_new(0));
				} else
					Stack_push(sp, AP_mod(x, y));
				AP_free(&x);
				AP_free(&y);
				break;
			}
		case '^': 
			{
				AP_T y = pop(), x = pop();
				if (AP_cmpi(y, 0) <= 0) {
					Fmt_fprint(stderr, "?nonpositive power\n");
					Stack_push(sp, AP_new(0));
				} else
					Stack_push(sp, AP_pow(x, y, NULL));
				AP_free(&x);
				AP_free(&y);
				break;
			}
		case 'd': 
			{
				AP_T x = pop();
				Stack_push(sp, x);
				Stack_push(sp, AP_addi(x, 0));
				break;
			}
		case 'p': 
			{
				AP_T x = pop();
				Fmt_print("%D\n", x);
				Stack_push(sp, x);
				break;
			}
		case 'f':
			if (!Stack_empty(sp)) 
			{
				Stack_T tmp = Stack_new();
				while (!Stack_empty(sp)) {
					AP_T x = pop();
					Fmt_print("%D\n", x);
					Stack_push(tmp, x);
				}
				while (!Stack_empty(tmp))
					Stack_push(sp, Stack_pop(tmp));
				Stack_free(&tmp);
			}
			break;
		case '~': 
			{
				AP_T x = pop();
				Stack_push(sp, AP_neg(x));
				AP_free(&x);
				break;
			}
		case 'c': while (!Stack_empty(sp)) 
				  {
					  AP_T x = Stack_pop(sp);
					  AP_free(&x);
				  } break;
		case 'q': while (!Stack_empty(sp)) 
				  {
					  AP_T x = Stack_pop(sp);
					  AP_free(&x);
				  }
			Stack_free(&sp);
			return EXIT_SUCCESS;
		default:
			if (isprint(c))
				Fmt_fprint(stderr, "?'%c'", c);
			else
				Fmt_fprint(stderr, "?'\\%03o'", c);
			Fmt_fprint(stderr, " is unimplemented\n");
			break;
		}
		while (!Stack_empty(sp)) 
		{
			AP_T x = Stack_pop(sp);
			AP_free(&x);
		}
		Stack_free(&sp);
		return EXIT_SUCCESS;
}