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,
18       int option, void **exist_ptr);
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20       void *tst_search(struct tst *tst, const unsigned char *key);
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22       void *tst_delete(struct tst *tst, const unsigned char *key);
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DESCRIPTION

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

71       Converted to POD from Peter A. Friend's ternary search trie
72       documentation by Alex Kiernan <alex.kiernan@thus.net> for
73       InterNetNews 2.4.0.
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75       $Id: tst.pod 8200 2008-11-30 13:31:30Z iulius $
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79INN 2.5.2                         2010-08-11                            tst(3)
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