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tst(3)


NAME

  tst - ternary search trie functions


SYNOPSIS

  #include <inn/tst.h>

  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);


DESCRIPTION

  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 assocaited with that key.

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


HISTORY

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

  $Id: tst.3,v 1.1 2003/01/02 12:22:14 vinocur Exp $

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