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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define MAXTOKEN 100
#define OUTLEN 1000
#define MAXBUFF 100
enum { NAME, PARENS, BRACKETS };
enum { NO, YES };
void err(char *s);
void errmsg(char *s);
void dcl(void);
void dirdcl(void);
int gettoken(void);
int tokentype;
int prevtoken;
char token[MAXTOKEN];
char name[MAXTOKEN];
char datatype[MAXTOKEN];
char out[OUTLEN];
char buff[MAXBUFF];
static size_t top;
void errmsg(char *s)
{
printf("err: %s\n", s);
prevtoken = YES;
}
void err(char *s)
{
printf("fatal error: %s\n", s);
exit(1);
}
void dcl(void)
{
int ns;
for (ns = 0; gettoken() == '*';)
ns++;
dirdcl();
while (ns-- > 0)
strcat(out, " pointer to");
}
void dirdcl(void)
{
int type;
if (tokentype == '(') {
dcl();
if (tokentype != ')')
errmsg("missing )");
} else if (tokentype == NAME) {
strcpy(name, token);
} else {
errmsg("expected name or (dcl)");
}
while ((type = gettoken()) == PARENS || type == BRACKETS) {
if (type == PARENS) {
strcat(out, " function returning");
} else {
strcat(out, " array");
strcat(out, token);
strcat(out, " of");
}
}
}
int gettoken(void)
{
char c, *p = token;
char getch(void);
void ungetch(char);
if (prevtoken == YES) {
prevtoken = NO;
return tokentype;
}
while(isblank(c = getch()))
;
if (c == '/') { /* ignore comments */
if ((c = getch()) == '/') {
while ((c = getch()) != '\n')
;
} else if (c == '*') {
while (getch() != '*' || (c = getch()) != '/')
if (c == '*')
ungetch('*');
return gettoken();
} else {
ungetch(c);
c = '/';
}
}
if (c == '(') {
if ((c = getch()) == ')') {
strcpy(token, "()");
return tokentype = PARENS;
} else {
ungetch(c);
return tokentype = '(';
}
} else if (c == '[') {
for (*p++ = '['; (*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;
}
}
void ungetch(char c)
{
if (top < MAXBUFF)
buff[top++] = c;
else
err("stack overflow");
}
char getch(void)
{
return (top > 0) ? buff[--top] : getchar();
}
int main(void)
{
while (gettoken() != EOF) {
if (tokentype == '\n') /* skip empty lines */
continue;
strcpy(datatype, token);
out[0] = '\0';
dcl();
if (tokentype != '\n')
printf("synatx error\n");
printf("%s: %s %s\n", name, out, datatype);
}
return 0;
}
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