[SOLVED] Predicate and apply function overexposure

predicate_t and apply_t are defined as:

typedef int (*predicate_t)(const node_t *ref, const struct info_stack *info);

typedef void (*apply_t)(node_t *ref, const struct info_stack *info);

which exposes too much information to the user who when writing a predicate or an apply function had to call the X_data function to extract and then cast the data held by the node to the appropiate node type and also had to access the user info from the info_stack struct.

With the creation of typed interfaces (see typed_adapters.h), predicates and apply functions can be defined with direct access to the typed pointer to the data and the user information pointer.

int typed_predicate(const TYPE *data, void *info)

void typed_apply(TYPE *data, void *info)

[SOLVED] Existential NULL check

In graph.c if you look at the e_loop function you will notice that unlike u_loop, e_loop doesn't NULL check whether the referred node is NULL before calling the apply function. This is correct and its purpose is to allow for insertion. It means that a new node must be appended at that reference. This however will throw a SEGV, so users always had to check for a reference that pointed to NULL when writing an apply function. This check is no longer required as it was absorbed by the typed adapters to the predicate and apply functions, so typed apply functions don't need to check for references pointing to NULL.

[UGLY SOLUTION] Indirect access to user information

struct info_insert is used by the insert functions to specify the data to be copied to the new node's data storage and its size, and it is also used by the in functions of the typed interfaces to store the key object and can be used by some typed interfaces to delete or access objects with the equ_preicate. This means that the user information isn't passed directly but through a member pointer of struct info_insert, requiring one extra dereference by users. Currently, the CAST_USER_INFO macro in typed_adapters.h can be used as a short way of doing this but it is not very elegant.