generic_array.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <stdint.h>

typedef struct fixed_point {
	long long i; // integer part
	unsigned long long d; // decimal part
} fixed_point;

#define DEFINE_ARRAY_TYPE(T) \
typedef struct array_ ## T { size_t sz; T d[]; } array_ ## T; \
void array_print_ ## T (const array_ ## T *a) \
{ \
	printf("{ "); \
	if (a->sz > 0) print_ ## T (&a->d[0]); \
	for (size_t i = 1; i < a->sz; i++) { \
		printf(", "); \
		print_ ## T (&a->d[i]); \
	} \
	printf(" }\n"); \
} \
array_ ## T * array_ ## T ## _new(size_t n) \
{ \
	array_ ## T *a = malloc(sizeof(array_ ## T) + sizeof(T[n])); \
	if (a) a->sz = n; \
	return a; \
} \
array_ ## T * array_ ## T ## _new_zero(size_t n) \
{ \
	array_ ## T *a = calloc(sizeof(array_ ## T) + sizeof(T[n]), 1); \
	if (a) a->sz = n; \
	return a; \
} \
array_ ## T * array_ ## T ## _new_init(size_t n, size_t m, const T v[m]) \
{ \
	array_ ## T *a = array_ ## T ## _new(n); \
	if (a) { \
		size_t i; \
		for (i = 0; i < m; i++) a->d[i] = v[i]; \
		if (i < n) memset(a->d+i, 0, sizeof(T)*(n-m)); \
	} \
	return a; \
}

#define ARRAY(T, ...) (T []){ __VA_ARGS__ }
#define ARRAY_SZ(a) (sizeof((a))/sizeof((a)[0]))
#define ARRAY_NEW(T, sz) array_ ## T ## _new((sz))
#define ARRAY_NEW_INIT(T, sz, a) array_ ## T ## _new_init(sz, ARRAY_SZ((a)), (a))
#define ARRAY_NEW_COPY(T, a) array_ ## T ## _new_init(ARRAY_SZ((a)), ARRAY_SZ((a)), (a))

#define print_format(x) _Generic((x), \
	char: "%c", \
	int: "%d", \
	float: "%f", \
	double: "%f", \
	default: "unknown_type")

#define GEN_PRINT_FUNC(T) \
void print_ ## T (const T *x) \
{ \
	printf(print_format(*(x)), *(x)); \
}

#define SUPPORTED_ARRAY_TYPES(X) \
	X(char) \
	X(int) \
	X(float) \
	X(double) \
	X(fixed_point)

GEN_PRINT_FUNC(char)
GEN_PRINT_FUNC(int)
GEN_PRINT_FUNC(float)
GEN_PRINT_FUNC(double)

void print_fixed_point(const fixed_point *fp)
{
	printf("%lld.%llu", fp->i, fp->d);
}

SUPPORTED_ARRAY_TYPES(DEFINE_ARRAY_TYPE)

void array_print_default(void *p) { puts("unknown_array_type"); }
#define array_print_LIST(T) \
	array_ ## T *: array_print_ ## T, \
	const array_ ## T *: array_print_ ## T,

#define array_print(a) _Generic((a), \
	SUPPORTED_ARRAY_TYPES(array_print_LIST) \
	default: array_print_default)((a))

void print_string(const array_char *s)
{
	printf("%s\n", s->d);
}

int main(void)
{
	array_char *s = ARRAY_NEW_COPY(char, "ebin");
	array_int *i = ARRAY_NEW_COPY(int, ARRAY(int, 1, 2, 3));
	array_float *f = ARRAY_NEW_COPY(float, ARRAY(float, 100, INFINITY, NAN));
	array_double *d = ARRAY_NEW_COPY(double, ARRAY(double, 333.333, 222.222, 111.111));
	array_fixed_point *fp = ARRAY_NEW_COPY(fixed_point, ARRAY(fixed_point, {1,234}, {90,2143}));

	array_print(s);
	print_string(s);
	array_print(i);
	array_print(f);
	array_print(d);
	array_print(fp);

	int i2[] = { 3, 2, 1 };
	memcpy(i->d, &i2, sizeof(i2));
	array_print(i);

	array_int *i3 = ARRAY_NEW_INIT(int, 4, ARRAY(int, 123, 234, 345));
	array_print(i3);

	array_int *i4 = array_int_new_zero(10);
	array_print(i4);

	array_int *i5 = array_int_new(0);
	array_print(i5);

	array_int *i6 = ARRAY_NEW_INIT(int, 4, ARRAY(int, 123, 234, 345, 456, 567));
	array_print(i6);

	free(s);
	free(i);
	free(f);
	free(d);
	free(fp);
	free(i3);
	free(i4);
	free(i5);
	free(i6);

	return 0;
}