libinn_tst(3)

1libinn_tst(3)             InterNetNews Documentation             libinn_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           enum tst_constants {
12               TST_OK,
13               TST_NULL_KEY,
14               TST_NULL_DATA,
15               TST_DUPLICATE_KEY,
16               TST_REPLACE
17           };
18
19           struct tst;
20
21           struct tst *tst_init(int node_line_width);
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23           void tst_cleanup(struct tst *tst);
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25           int tst_insert(struct tst *tst, const unsigned char *key,
26                          void *data, int option, void **exist_ptr);
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28           void *tst_search(struct tst *tst, const unsigned char *key);
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30           void *tst_delete(struct tst *tst, const unsigned char *key);
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DESCRIPTION

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

79       Converted to POD from Peter A. Friend's ternary search trie
80       documentation by Alex Kiernan <alex.kiernan@thus.net> for
81       InterNetNews 2.4.0.
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NAME

SYNOPSIS

DESCRIPTION

HISTORY

SEE ALSO