#ifndef __STDIO_P_H__
# define __STDIO_P_H__

#include <stdio.h>
#include <stdbool.h>

/*
** General utilities for scanf(); we expose them here as we use subfunctions of
** strto*() from <stdlib.h> to implement numerical specifiers.
*/

/*
** Input for scanf; exactly one of str and fp must be non-NULL. We include a
** single-character buffer for convenience for scanning functions to test the
** next character, which can be flushed back by ungetc().
*/
struct __scanf_input {
	char const * __restrict__ str;
	FILE *fp;

	// max char to read from the input stream as per user length modifier
	int readmaxlength;
	int currentlength;

	// total number of char read so far in the current call of a XYscanf() function (to return a %n when required)
	int readsofar;

	int buffer;
};


/* Generic formatted scaning. */
extern int __scanf(
	struct __scanf_input * __restrict__ __in,
	char const * __restrict__ __format,
	va_list *__args);


/* Initialize the input by feeding the buffer byte. */
void __scanf_start(struct __scanf_input *__in);

/* Fetch the next byte from the input and return it (don't call directly). */
int __scanf_fetch(struct __scanf_input *__in);

/* Read the next byte while maintaining the buffer. */
static inline int __scanf_in(struct __scanf_input *__in)
{
	int c = __in->buffer;
	__in->buffer = __scanf_fetch(__in);
	__in->readsofar++;
	__in->currentlength++;
	return c;
}

/* Peek the next byte without advancing. */
static inline int __scanf_peek(struct __scanf_input *__in)
{
	if (__in->readmaxlength==-1 || __in->currentlength<__in->readmaxlength )
		return __in->buffer;
	else return 0;
}

/* Close the input by unsending the buffer once finished. */
void __scanf_end(struct __scanf_input *__in);

#endif /* __STDIO_P_H__ */