cp_narytree

Section: libcprops - cp_narytree (3)
Updated: SEPTEMBER 2006
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NAME

cp_narytree_insert, cp_narytree_get, cp_narytree_delete, cp_narytree_contains, cp_narytree_callback, cp_narytree_count - N-ary tree operations

SYNOPSIS

#include <cprops/nary.h>
#include <cprops/vector.h>

void *cp_narytree_insert(cp_narytree *tree, void *key, void *value);
void *cp_narytree_get(cp_narytree *tree, void *key);
void *cp_narytree_delete(cp_narytree *tree, void *key);
int cp_narytree_contains(cp_narytree *tree, void *key);
int cp_narytree_callback(cp_narytree *tree,
cp_callback_fn callback,
void *prm)
long cp_narytree_count(cp_narytree *tree);

DESCRIPTION

cp_narytree_insert adds a mapping for the given key to the given value. If a mapping for the given key already exists and COLLECTION_MODE_MULTIPLE_VALUES is not set, the current mapping is replaced, and, if COLLECTION_MODE_DEEP is set, the old mapping key and value are destroyed. If COLLECTION_MODE_MULTIPLE_VALUES is set, the new value is added to the existing values mapped to the given key. By default COLLECTION_MODE_MULTIPLE_VALUES is not set.
If COLLECTION_MODE_COPY is set, the given key and value parameters are copied before being inserted. Unless COLLECTION_MODE_NOSYNC is set, the insert function will write-lock the tree before performing the insertion.

cp_narytree_get returns the current mapping for the requested key or NULL if none exists. Unless COLLECTION_MODE_NOSYNC is set, the tree is read-locked. If COLLECTION_MODE_MULTIPLE_VALUES is set, the returned value is a cp_vector(3) object containing all values for the given key.

cp_narytree_delete removes the current mapping for the given key and returns the value associated to it or NULL if there was no mapping for the given key. The return value is usable to indicate that a deletion has taken place. Note that the returned pointer may be invalid if COLLECTION_MODE_DEEP is set and the tree has a non-null value destructor function set. Unless COLLECTION_MODE_NOSYNC is set, the deletion function write-locks the tree.

cp_narytree_contains returns non-zero if the tree contains a mapping for the given key or zero if not.

cp_narytree_callback performs an in-order scan of the table by mapping comparison order, invoking thegiven callback function with each mapping and the given parameter. The callback iteration is terminated if the callback function returns non-zero. The prototype for the callback function is as follows:

int callback_fn(void *entry, void *client_prm);

The callback function is invoked iteratively with entry pointing of the current table node. Here is an example callback function implementation, which prints the key and value addresses for each mapping:

int callback(void *entry, void *prm)
{
    cp_mapping *mapping = entry;
        printf("key %p, value %p, mapping->key, mapping->value);
        return 0;
}

cp_narytree_count returns the number of mappings currently stored in a tree.

RETURN VALUE

cp_narytree_insert and cp_narytree_delete return the affected value on success or NULL on failure. cp_narytree_get returns the value mapped to the requested key or NULL on failure or if no such mapping exists.

Note that these functions may fail if locking fails. This means that for a synchronized table (ie COLLECTION_MODE_NOSYNC not set), cp_narytree_get could return NULL although a mapping actually exists. Applications should check errno to determine whether no mapping was found (errno not set) or locking has failed (errno will be set to EBUSY, EINVAL or EDEADLK).

cp_narytree_contains returns non-zero if the tree contains a mapping for the requested key or zero if no mapping was found or on locking errors - see above.

cp_narytree_callback returns 0 if the iteration completes successfully, -1 on locking errors, or the non-zero value returned by the callback function causing the iteration to abort.

cp_narytree_count returns the number of mappings currently stored.