#ifndef __CMAYBE_H__
#define __CMAYBE_H__

#define MAYBE_TYPE(name, type) struct maybe_##name {type value; char is_value;}
#define MAYBE(name) struct maybe_##name

#define ENABLE_RETURN(name) MAYBE(name) __return_value
#define RETURN_VALUE(x) {\
	__return_value.is_value = 1;\
	__return_value.value = x;\
	return __return_value;\
}
#define RETURN_NOTHING() {\
	__return_value.is_value = 0;\
	return __return_value;\
}

#define IS_VALUE(x) if ((x).is_value)
#define IS_NOT_VALUE(x) if (!(x).is_value)
#define VALUE(x) (x).value

struct __free_list {
	struct __free_list *next;
	void *ptr;
};
#define ENABLE_TRY() \
	struct __free_list *__allocations = NULL, *__free_list_node;\
	void *__allocation, *__old_allocation;\
	jmp_buf __try_fail_jmp_buf;\
	if (setjmp(__try_fail_jmp_buf)) {\
		TRY_FREE_ALL();\
		RETURN_NOTHING();\
	}
#define TRY_TYPE(name) MAYBE(name) __try_tmp_##name
#define TRY(name, maybe_value) (\
	__try_tmp_##name = maybe_value,\
	(__try_tmp_##name.is_value ? 0 :\
		longjmp(__try_fail_jmp_buf, 1)\
	),\
	__try_tmp_##name.value\
)

#define TRY_MEMALLOC(allocator, ...) (\
	__free_list_node = malloc(sizeof(struct __free_list)),\
	(__free_list_node == NULL ? longjmp(__try_fail_jmp_buf, 1) : 0),\
	__allocation = allocator(__VA_ARGS__),\
	(__allocation == NULL ? (\
		free(__free_list_node),\
		longjmp(__try_fail_jmp_buf, 1)\
	) : (\
		__free_list_node->next = __allocations,\
		__free_list_node->ptr = __allocation,\
		__allocations = __free_list_node\
	)),\
	__allocation\
)
#define TRY_MALLOC(size) TRY_MEMALLOC(malloc, size)

static void __remove_free_list(struct __free_list **head, void *ptr) {
	struct __free_list **current = head;
	while (*current != NULL) {
		if (current[0]->ptr == ptr) {
			*current = current[0]->next;
			break;
		}
		current = &current[0]->next;
	}
}
#define TRY_FREE(allocation) (\
	free(allocation),\
	__remove_free_list(&__allocations, allocation)\
)
#define TRY_FREE_ALL() \
	while (__allocations != NULL) {\
		struct __free_list *current = __allocations;\
		free(current->ptr);\
		__allocations = current->next;\
		free(current);\
	}

static void __replace_free_list(struct __free_list **head, void *from, void *to) {
	struct __free_list **current = head;
	while (*current != NULL) {
		if (current[0]->ptr == from) {
			current[0]->ptr = to;
			break;
		}
		current = &current[0]->next;
	}
}
#define TRY_MEMREALLOC(reallocator, old, ...) (\
	__old_allocation = old,\
	__allocation = reallocator(old, __VA_ARGS__),\
	(__allocation == NULL ? (\
		longjmp(__try_fail_jmp_buf, 1)\
	) : \
		__replace_free_list(&__allocations, __old_allocation, __allocation)\
	),\
	__allocation\
)
#define TRY_REALLOC(old, size) TRY_MEMREALLOC(realloc, old, size)

#endif