#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;
	void (*freer)(void*);
};
#define ENABLE_TRY() \
	struct __free_list *__allocations = NULL, *__free_list_node;\
	void *__allocation;\
	jmp_buf __try_fail_jmp_buf;\
	if (setjmp(__try_fail_jmp_buf)) {\
		TRY_FAIL_HANDLE();\
		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 HANDLE_ON_TRY_FAIL(freer_func, pointer) (\
	__allocation = pointer,\
	__free_list_node = malloc(sizeof(struct __free_list)),\
	(__free_list_node == NULL ? (\
		free(__allocation),\
		longjmp(__try_fail_jmp_buf, 1)\
	) : (\
		__free_list_node->next = __allocations,\
		__free_list_node->ptr = __allocation,\
		__free_list_node->freer = freer_func,\
		__allocations = __free_list_node\
	)),\
	__allocation\
)
#define FREE_ON_TRY_FAIL(pointer) HANDLE_ON_TRY_FAIL(free, pointer)

static void __remove_free_list(struct __free_list **head, void *ptr, void (*free)(void*)) {
	struct __free_list **current = head;
	while (*current != NULL) {
		if (current[0]->ptr == ptr) {
			struct __free_list *deleted = *current;
			*current = deleted->next;
			free(deleted);
			break;
		}
		current = &current[0]->next;
	}
}

#define TRY_HOF_REMOVE(allocation) __remove_free_list(&__allocations, allocation, free)
#define TRY_FAIL_HANDLE() \
	while (__allocations != NULL) {\
		struct __free_list *current = __allocations;\
		void (*freer)(void*) = current->freer;\
		freer(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_HOF_REPLACE(old_ptr, new_ptr) __replace_free_list(&__allocations, old_ptr, new_ptr)

#endif