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

#define	MAXTOKENS 100
#define MAXTOKENLEN 64

enum type_tag { IDENTIFIED, QUALIFIER, TYPE };

struct token {
	char type;
	char string[MAXTOKENLEN];
};

int top = -1;
struct token stack[MAXTOKENS];
struct token this;

#define pop stack[top--]
#define push(s) stack[++top] = s;

enum type_tag classify_string(void)
{
	char *s = this.string;
	if (!strcmp(s, "const"))
	{
		strcpy(s, "read-only");
		return QUALIFIER;
	}
	if (!strcmp(s, "volatile"))	return QUALIFIER;
	if (!strcmp(s, "void"))	return TYPE;
	if (!strcmp(s, "char"))	return TYPE;
	if (!strcmp(s, "signed")) return TYPE;
	if (!strcmp(s, "unsigned"))	return TYPE;
	if (!strcmp(s, "short")) return TYPE;
	if (!strcmp(s, "int")) return TYPE;
	if (!strcmp(s, "long")) return TYPE;
	if (!strcmp(s, "float")) return TYPE;
	if (!strcmp(s, "double")) return TYPE;
	if (!strcmp(s, "struct")) return TYPE;
	if (!strcmp(s, "union")) return TYPE;
	if (!strcmp(s, "enum")) return TYPE;
	return IDENTIFIED;

}


void gettoken(void)
{
	char *p = this.string;
	/* 略过空白字符 */
	while ((*p = getchar()) == ' ');
	if (isalnum(*p))
	{
		/*读入的标识符以A-Z,0-9开头。  */
		while (isalnum( *++p = getchar() ));
		ungetc(*p, stdin);
		*p = '\0';
		this.type = classify_string();
		return;
	}
	if (*p == '*')
	{
		strcpy(this.string, "pointer to");
		this.type = '*';
		return;
	}
	this.string[1] = '\0';
	this.type = *p;
	return;
}


void read_to_first_identifer(void)
{
	gettoken();
	while (this.type != IDENTIFIED)
	{
		push(this);
		gettoken();
	}
	printf("%s is \n", this.string);
	gettoken();
    return;
}

void deal_with_arrays(void)
{
	while (this.type == '[')
	{
		printf("array ");
		gettoken();
		if (isdigit(this.string[0]))
		{
			printf("0..%d", atoi(this.string) - 1);
			gettoken();
		}
		gettoken();
		printf(" of ");
	}
}

void deal_with_function_args()
{
	while(this.type != ')'){
		gettoken();
	}
	gettoken();
	printf("function returning ");
}

void deal_with_pointers()
{
	while (stack[top].type == '*')
	{
		printf("%s ", pop.string);
	}
}


void deal__with_declarator()
{
	switch (this.type)
	{
		case '[': deal_with_arrays(); break;
		case '(': deal_with_function_args();
	}
	deal_with_pointers();
	while (top >= 0)
	{
		if (stack[top].type == '(')
		{
			pop;
			gettoken();
			deal__with_declarator();
		}else {
			printf("%s ", pop.string);
		}
	}
}
int main()
{
	/* 将标记压入堆栈中，直到遇到标识符 */
	read_to_first_identifer();
	deal__with_declarator();
	printf("\n");
	return 0;
}