cdecl

cdecl.c

/*
 * cdecl
 */
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>

#define MAXTOKEN 100
enum TokenType {NAME, PARENS, BRACKETS};
void dcl();
void dirdcl();
int gettoken();

int tokentype;
char token[MAXTOKEN];
char name[MAXTOKEN];
char datatype[MAXTOKEN];
char out[10086];

void dcl()
{
    int ns;

    for (ns = 0; gettoken() == '*';) /* count *'s */
        ++ns;
    dirdcl();
    while (ns-- > 0)
        strcat(out, " pointer to");
}

void dirdcl()
{
    int type;

    if (tokentype == '(')
    {
        dcl();
        if (tokentype != ')')
        {
            fprintf(stderr, "error: missing )\n");
            exit(EXIT_FAILURE);
        }
    }
    else if (tokentype == NAME)
        strcpy(name, token);
    else
    {
        fprintf(stderr, "error: expected name or (dcl)\n");
        exit(EXIT_FAILURE);
    }

    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()
{
    int c;
    char* p = token;

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

int main()
{
    printf("input your declarelation statement:\n");

    while (gettoken() != EOF)
    {
        strcpy(datatype, token);
        out[0] = '\0';
        dcl();
        if (tokentype != '\n')
        {
            fprintf(stderr, "syntax error!\n");
            exit(EXIT_FAILURE);
        }
        printf("%s: %s %s\n", name, out, datatype);
    }
    return EXIT_SUCCESS;
}