EX_03/level-1/scanf/ft_scanf.c

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


int match_space(FILE *f)
{
    int ch;
    
    while ((ch = fgetc(f)) != EOF && isspace(ch))
    {}
    
    if (ch != EOF)
        ungetc(ch, f);
    
    if (ferror(f))
        return -1;
        
    return 1;
}

int match_char(FILE *f, char c)
{
    int ch = fgetc(f);
    if (ch == c)
        return 1;
    
    if (ch != EOF)
        ungetc(ch, f);
        
    return -1;
}

int scan_char(FILE *f, va_list ap)
{
    int ch = fgetc(f);
    char *cp = va_arg(ap, char *);

    if (ch == EOF)
        return -1;
    
    *cp = (char)ch;
    return 1;
}

int scan_int(FILE *f, va_list ap)
{
    int *ip = va_arg(ap, int *);
    int value = 0;
    int sign = 1;
    int ch;

    ch = fgetc(f);
    
    if (ch == '-')
    {
        sign = -1;
        ch = fgetc(f);
    }
    else if (ch == '+')
    {
        ch = fgetc(f);
    }
    
    if (!isdigit(ch))
    {
        if (ch != EOF)
            ungetc(ch, f);
        return -1;
    }

    while (isdigit(ch))
    {
        value = value * 10 + (ch - '0');
        ch = fgetc(f);
    }

    if (ch != EOF)
        ungetc(ch, f);
    
    *ip = value * sign;
    return 1;
}

int scan_string(FILE *f, va_list ap)
{
    char *sp = va_arg(ap, char *);
    int i = 0;
    int ch;

    ch = fgetc(f);
    if (ch == EOF)
        return -1;

    while (ch != EOF && !isspace(ch))
    {
        sp[i++] = (char)ch;
        ch = fgetc(f);
    }
    sp[i] = '\0';
    
    if (ch != EOF)
        ungetc(ch, f);
    
    return 1;
}

int match_conv(FILE *f, const char **format, va_list ap)
{
    switch (**format)
    {
        case 'c':
            return scan_char(f, ap);
        case 'd':
            match_space(f);
            return scan_int(f, ap);
        case 's':
            match_space(f);
            return scan_string(f, ap);
        case '\0':
            return -1;
        default:
            return -1;
    }
}

int ft_vfscanf(FILE *f, const char *format, va_list ap)
{
    int nconv = 0;
 
    int c = fgetc(f);
    if (c == EOF)
        return EOF;
    ungetc(c, f);

    while (*format)
    {
        if (*format == '%')
        {
            format++;
            if (match_conv(f, &format, ap) != 1)
                break;
            else
                nconv++;
        }
        else if (isspace(*format))
        {
            if (match_space(f) == -1)
                break;
        }
        else
        {
            if (match_char(f, *format) != 1)
                break;
        }
        format++;
    }
    
    if (ferror(f))
        return EOF;
    
    return nconv;
}

int ft_scanf(const char *format, ...)
{
    va_list ap;

    va_start(ap, format);
    int ret = ft_vfscanf(stdin, format, ap);
    va_end(ap);
    
    return ret;
}