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| #include <stdio.h>
#include <string.h>
#include <ctype.h>
#define MAXTOKEN 100
#define BUFSIZE 100
enum {NAME, PARENS, BRACKETS};
enum {NO, YES};
void dcl(void); //parse a declarator
void dirdcl(void); //parse a direct declarator
int gettoken(void);
void paramdcl(void); //declarator analysis with parameters
void declspec(void); //specification declaration
int typespec(void); //type specifier
int typedesc(void); //descriptor type
int getch(void); //get a (possibly pushed-back) character
void ungetch(int c); //push character back on input
void errmesg(char *msg); //error message
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 buf[BUFSIZE]; //buffer for ungetch;
char out[1000];
int errtoken = NO;
int errbrack = NO;
/* convert declaration to words */
int main()
{
while(gettoken() != EOF) //1st token on line
{
strcpy(datatype, token); //is the datatype
out[0] = '\0';
dcl(); //parse rest of line
if(tokentype != '\n')
printf("syntax error\n");
printf("%s: %s %s\n", name, out, datatype);
}
return 0;
}
/* dcl: parse a declarator */
void dcl(void)
{
int ns;
for(ns = 0; gettoken() == '*';) //count stars
ns++;
dirdcl();
while(ns-- > 0)
strcat(out, " pointer to");
}
/* dirdcl: parse a direct declarator */
void dirdcl(void)
{
int type;
if(tokentype == '(') //(dcl)
{
dcl();
if(tokentype != ')')
errmesg("error: missing )\n");
}
else if(tokentype == NAME) //variable name
{
if(name[0] == '\0')
strcpy(name, token);
}
else
errtoken = YES;
while((type = gettoken()) == PARENS || type == BRACKETS || type == '(')
if(type == PARENS)
strcat(out, " function returning");
else if(type == '(')
{
strcat(out, " function taking");
paramdcl();
strcat(out, " and returning");
}
else
{
strcat(out, " array");
strcat(out, token);
strcat(out, " of");
}
}
/* errmesg: error message */
void errmesg(char *msg)
{
printf("%s", msg);
errtoken = YES;
}
/* paramdcl: declarator analysis with parameters */
void paramdcl(void)
{
do
{
declspec(); //specification declaration
} while(tokentype == ',');
if(tokentype != ')')
errmesg("missing ) in declarator of parameters\n");
}
/* specification declaration */
void declspec(void)
{
char temp[MAXTOKEN];
temp[0] = '\0';
gettoken();
do
{
if(tokentype != NAME)
{
errtoken = YES;
dcl();
}
else if(typespec() == YES) // type specifier
{
strcat(temp, " ");
strcat(temp, token);
gettoken();
}
else if(typedesc() == YES) //descriptor type
{
strcat(temp, " ");
strcat(temp, token);
gettoken();
}
else
errmesg("error: unknown type in the parameter list\n");
} while(tokentype != ',' && tokentype != ')');
strcat(out, temp);
if(tokentype == ',')
strcat(out, ",");
}
/* type specifier */
int typespec(void)
{
static char *types[] = {"char", "int", "void"};
char *ptypes = token;
int result, i;
result = NO;
for(i = 0; i < 3; i++)
if(strcmp(ptypes, *(types + i)) != 0)
result = NO;
else
{
result = YES;
return result;
}
return result;
}
/* descriptor type */
int typedesc(void)
{
static char *typed[] = {"const", "volatile"};
char *ptd = token;
int result, i;
result = NO;
for(i = 0; i < 2; i++)
if(strcmp(ptd, *(typed + i)) != 0)
result = NO;
else
{
result = YES;
return result;
}
return result;
}
int gettoken(void)
{
int c;
char *p = token;
if(errtoken == YES)
{
errtoken = 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 != ']';)
{
*p = getch();
if(*p != ']')
{
if(*p == '\n' || *p == ')' || *p == '(')
{
printf("error: missing ]\n");
ungetch(*p);
*p = ']';
}
else
p++;
}
}
*++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;
}
int bufp = 0;
int getch(void) // get a (possibly pushed-back) character
{
int bufp = 0; //next free position in buf
return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c) // push character back on input
{
if(bufp >= BUFSIZE)
printf("ungetch: too many characnters\n");
else
buf[bufp++] = c;
} |
(
