1tst(3)                    InterNetNews Documentation                    tst(3)
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NAME

6       tst - ternary search trie functions
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SYNOPSIS

9           #include <inn/tst.h>
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11           struct tst;
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13           struct tst *tst_init(int node_line_width);
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15           void tst_cleanup(struct tst *tst);
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17           int tst_insert(struct tst *tst, const unsigned char *key, void *data, int option, void **exist_ptr);
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19           void *tst_search(struct tst *tst, const unsigned char *key);
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21           void *tst_delete(struct tst *tst, const unsigned char *key);
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DESCRIPTION

24       tst_init allocates memory for members of struct tst, and allocates the
25       first node_line_width nodes. A NULL pointer is returned by tst_init if
26       any part of the memory allocation fails. On success, a pointer to a
27       struct tst is returned.
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29       The value for node_line_width must be chosen very carefully. One node
30       is required for every character in the tree. If you choose a value that
31       is too small, your application will spend too much time calling
32       malloc(3) and your node space will be too spread out. Too large a value
33       is just a waste of space.
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35       tst_cleanup frees all memory allocated to nodes, internal structures,
36       as well as tst itself.
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38       tst_insert inserts the string key into the tree. Behavior when a
39       duplicate key is inserted is controlled by option. If key is already in
40       the tree then TST_DUPLICATE_KEY is returned, and the data pointer for
41       the existing key is placed in exist_ptr.  If option is set to
42       TST_REPLACE then the existing data pointer for the existing key is
43       replaced by data.  Note that the old data pointer will still be placed
44       in exist_ptr.
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46       If a duplicate key is encountered and option is not set to TST_REPLACE
47       then TST_DUPLICATE_KEY is returned. If key is zero length then
48       TST_NULL_KEY is returned. A successful insert or replace returns
49       TST_OK. A return value of TST_ERROR indicates that a memory allocation
50       error occurred while trying to grow the node free.
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52       Note that the data argument must never be NULL. If it is, then calls to
53       tst_search will fail for a key that exists because the data value was
54       set to NULL, which is what tst_search returns. If you just want a
55       simple existence tree, use the tst pointer as the data pointer.
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57       tst_search finds the string key in the tree if it exists and returns
58       the data pointer associated with that key.
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60       If key is not found then NULL is returned, otherwise the data pointer
61       associated with key is returned.
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63       tst_delete deletes the string key from the tree if it exists and
64       returns the data pointer assocaited with that key.
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66       If key is not found then NULL is returned, otherwise the data pointer
67       associated with key is returned.
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HISTORY

70       Converted to POD from Peter A. Friend's ternary search trie
71       documentation by Alex Kiernan <alex.kiernan@thus.net> for
72       InterNetNews 2.4.0.
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74       $Id: tst.pod 9073 2010-05-31 19:00:23Z iulius $
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78INN 2.6.4                         2015-09-12                            tst(3)
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