~drizzle-trunk/drizzle/development

1 by brian
clean slate
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/* Copyright (C) 2005 MySQL AB
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   This program is free software; you can redistribute it and/or modify
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   it under the terms of the GNU General Public License as published by
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   the Free Software Foundation; version 2 of the License.
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   This program is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
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   along with this program; if not, write to the Free Software
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   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */
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#ifndef _trie_h
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#define _trie_h
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#ifdef	__cplusplus
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extern "C" {
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#endif
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typedef struct st_trie_node
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{
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  uint16 leaf;                /* Depth from root node if match, 0 else */
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  uchar c;                    /* Label on this edge */
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  struct st_trie_node *next;  /* Next label */
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  struct st_trie_node *links; /* Array of edges leaving this node */
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  struct st_trie_node *fail;  /* AC failure function */
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} TRIE_NODE;
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typedef struct st_trie
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{
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  TRIE_NODE root;
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  MEM_ROOT mem_root;
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  CHARSET_INFO *charset;
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  uint32 nnodes;
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  uint32 nwords;
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} TRIE;
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typedef struct st_ac_trie_state
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{
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  TRIE *trie;
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  TRIE_NODE *node;
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} AC_TRIE_STATE;
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extern TRIE *trie_init (TRIE *trie, CHARSET_INFO *charset);
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extern void trie_free (TRIE *trie);
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extern my_bool trie_insert (TRIE *trie, const uchar *key, uint keylen);
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extern my_bool ac_trie_prepare (TRIE *trie);
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extern void ac_trie_init (TRIE *trie, AC_TRIE_STATE *state);
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/* `trie_goto' is internal function and shouldn't be used. */
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static inline TRIE_NODE *trie_goto (TRIE_NODE *root, TRIE_NODE *node, uchar c)
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{
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  TRIE_NODE *next;
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  DBUG_ENTER("trie_goto");
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  for (next= node->links; next; next= next->next)
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    if (next->c == c)
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      DBUG_RETURN(next);
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  if (root == node)
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    DBUG_RETURN(root);
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  DBUG_RETURN(NULL);
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}
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/*
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  SYNOPSIS
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    int ac_trie_next (AC_TRIE_STATE *state, uchar *c);
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    state - valid pointer to `AC_TRIE_STATE'
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    c - character to lookup
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  DESCRIPTION
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    Implementation of search using Aho-Corasick automaton.
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    Performs char-by-char search.
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  RETURN VALUE
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    `ac_trie_next' returns length of matched word or 0.
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*/
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static inline int ac_trie_next (AC_TRIE_STATE *state, uchar *c)
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{
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  TRIE_NODE *root, *node;
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  DBUG_ENTER("ac_trie_next");
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  DBUG_ASSERT(state && c);
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  root= &state->trie->root;
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  node= state->node;
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  while (! (state->node= trie_goto(root, node, *c)))
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    node= node->fail;
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  DBUG_RETURN(state->node->leaf);
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}
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/*
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  SYNOPSIS
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    my_bool trie_search (TRIE *trie, const uchar *key, uint keylen);
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    trie - valid pointer to `TRIE'
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    key - valid pointer to key to insert
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    keylen - non-0 key length
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  DESCRIPTION
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    Performs key lookup in trie.
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  RETURN VALUE
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    `trie_search' returns `true' if key is in `trie'. Otherwise,
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    `false' is returned.
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  NOTES
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    Consecutive search here is "best by test". arrays are very short, so
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    binary search or hashing would add too much complexity that would
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    overweight speed gain. Especially because compiler can optimize simple
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    consecutive loop better (tested)
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*/
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static inline my_bool trie_search (TRIE *trie, const uchar *key, uint keylen)
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{
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  TRIE_NODE *node;
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  uint k;
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  DBUG_ENTER("trie_search");
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  DBUG_ASSERT(trie && key && keylen);
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  node= &trie->root;
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  for (k= 0; k < keylen; k++)
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  {
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    uchar p;
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    if (! (node= node->links))
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      DBUG_RETURN(FALSE);
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    p= key[k];
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    while (p != node->c)
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      if (! (node= node->next))
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        DBUG_RETURN(FALSE);
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  }
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  DBUG_RETURN(node->leaf > 0);
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}
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#ifdef	__cplusplus
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}
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#endif
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#endif