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
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
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 assocaited with that key.
If key is not found then NULL is returned, otherwise the data
pointer associated with key is returned.