tst - Ternary search trie functions
#include <inn/tst.h>
enum tst_constants {
TST_OK,
TST_NULL_KEY,
TST_NULL_DATA,
TST_DUPLICATE_KEY,
TST_REPLACE
};
struct tst;
struct tst *tst_init(int node_line_width);
void tst_cleanup(struct tst *tst);
int tst_insert(struct tst *tst, const unsigned char *key,
void *data, int option, void **exist_ptr);
void *tst_search(struct tst *tst, const unsigned char *key);
void *tst_delete(struct tst *tst, const unsigned char *key);
tst_init allocates memory for members of
struct tst, and allocates
the first
node_line_width nodes. A NULL pointer is returned by
tst_init if any part of the memory allocation fails. On success, a
pointer to a
struct tst is returned.
The value for
node_line_width must be chosen very carefully. One node is
required for every character in the tree. If you choose a value that is too
small, your application will spend too much time calling
malloc(3) and
your node space will be too spread out. Too large a value is just a waste of
space.
tst_cleanup frees all memory allocated to nodes, internal structures, as
well as
tst itself.
tst_insert inserts the string
key into the tree. Behavior when a
duplicate key is inserted is controlled by
option. If
key is
already in the tree, then "TST_DUPLICATE_KEY" is returned, and the
data pointer for the existing key is placed in
exist_ptr. If
option is set to "TST_REPLACE", then the existing data
pointer for the existing key is replaced by
data. Note that the old
data pointer will still be placed in
exist_ptr.
If a duplicate key is encountered and
option is not set to
"TST_REPLACE", then "TST_DUPLICATE_KEY" is returned. If
key is zero length, then "TST_NULL_KEY" is returned. A
successful insert or replace returns "TST_OK". A return value of
"TST_ERROR" indicates that a memory allocation error occurred while
trying to grow the node free.
Note that the
data argument must never be "NULL". If it is,
then calls to
tst_search will fail for a key that exists because the
data value was set to "NULL", which is what
tst_search
returns. If you just want a simple existence tree, use the
tst pointer
as the data pointer.
tst_search finds the string
key in the tree if it exists and
returns the data pointer associated with that key.
If
key is not found then "NULL" is returned, otherwise the data
pointer associated with
key is returned.
tst_delete deletes the string
key from the tree if it exists and
returns the data pointer associated with that key.
If
key is not found, then "NULL" is returned, otherwise the
data pointer associated with
key is returned.
Converted to POD from Peter A. Friend's ternary search trie documentation
by Alex Kiernan <
[email protected]> for InterNetNews 2.4.0.
libinn(3).