Exercise 5-19: undcl without redundant parentheses

Modify undcl so that it does not add redundant parentheses to declarations.

Each input line holds a word description as above: a name, then any of *, () and [n], then the data type. Print the declaration on a line of its own, with parentheses only where they're needed. The end of the input ends a line too.

The book's undcl program, which converts a word description such as x () * [] * () char back to a declaration (char (*(*x())[])()):

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

#define MAXTOKEN  100

enum { NAME, PARENS, BRACKETS };

void dcl(void);
void dirdcl(void);
int gettoken(void);

int tokentype;           /* type of last token */
char token[MAXTOKEN];    /* last token string */
char name[MAXTOKEN];     /* identifier name */
char datatype[MAXTOKEN]; /* data type = char, int, etc. */
char out[1000];

/* undcl:  convert word descriptions to declarations */
int main(void)
{
    int type;
    char temp[MAXTOKEN];

    while (gettoken() != EOF) {
        strcpy(out, token);
        while ((type = gettoken()) != '\n')
            if (type == PARENS || type == BRACKETS)
                strcat(out, token);
            else if (type == '*') {
                sprintf(temp, "(*%s)", out);
                strcpy(out, temp);
            } else if (type == NAME) {
                sprintf(temp, "%s %s", token, out);
                strcpy(out, temp);
            } else
                printf("invalid input at %s\n", token);
        printf("%s\n", out);
    }
    return 0;
}

int gettoken(void)  /* return next token */
{
    int c, getch(void);
    void ungetch(int);
    char *p = token;

    while ((c = getch()) == ' ' || c == '\t')
        ;
    if (c == '(') {
        if ((c = getch()) == ')') {
            strcpy(token, "()");
            return tokentype = PARENS;
        } else {
            ungetch(c);
            return tokentype = '(';
        }
    } else if (c == '[') {
        for (*p++ = c; (*p++ = getch()) != ']'; )
            ;
        *p = '\0';
        return tokentype = BRACKETS;
    } else if (isalpha(c)) {
        for (*p++ = c; isalnum(c = getch()); )
            *p++ = c;
        *p = '\0';
        ungetch(c);
        return tokentype = NAME;
    } else
        return tokentype = c;
}

#define BUFSIZE 100

char buf[BUFSIZE];    /* buffer for ungetch */
int bufp = 0;         /* next free position in buf */

int getch(void)  /* get a (possibly pushed-back) character */
{
    return (bufp > 0) ? buf[--bufp] : getchar();
}

void ungetch(int c)   /* push character back on input */
{
    if (bufp >= BUFSIZE)
        printf("ungetch: too many characters\n");
    else
        buf[bufp++] = c;
}