Exercise 5.19 - undcl does not add redundant parentheses#
Question#
Modify undcl so that it does not add redundant parentheses to declarations.
/* Modify undcl so that it does not add redundant parenthesiss to declarations */
#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 nexttoken(void);
int tokentype;
char token[MAXTOKEN]; /* last token string */
char out[1000];
/* undcl: convert word description to declaration */
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 == '*')
{
if((type = nexttoken()) == PARENS || type == BRACKETS)
sprintf(temp,"(*%s)",out);
else
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;
}
enum { NO, YES};
int gettoken(void);
/* nexttoken: get the next token and push it back */
int nexttoken(void)
{
int type;
extern int prevtoken;
type = gettoken();
prevtoken = YES;
return type;
}
#include<ctype.h>
#include<string.h>
extern int tokentype; /* type of last token */
extern char token[]; /* last token string */
int prevtoken = NO; /* there is no previous token */
int gettoken(void) /* return next token */
{
int c,getch(void);
void ungetch(int);
char *p = token;
if(prevtoken == YES)
{
prevtoken = NO;
return tokentype;
}
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;
int getch(void) /* get a(possibly pushed back) character */
{
return (bufp > 0) ? buf[--bufp]: getchar();
}
void ungetch(int c)
{
if(bufp >= BUFSIZE)
printf("ungetch: too many characters \n");
else
buf[bufp++] =c;
}