1/*
2** 2001 September 22
3**
4** The author disclaims copyright to this source code.  In place of
5** a legal notice, here is a blessing:
6**
7**    May you do good and not evil.
8**    May you find forgiveness for yourself and forgive others.
9**    May you share freely, never taking more than you give.
10**
11*************************************************************************
12** This is the header file for the generic hash-table implemenation
13** used in SQLite.  We've modified it slightly to serve as a standalone
14** hash table implementation for the full-text indexing module.
15**
16*/
17#ifndef _FTS3_HASH_H_
18#define _FTS3_HASH_H_
19
20/* Forward declarations of structures. */
21typedef struct Fts3Hash Fts3Hash;
22typedef struct Fts3HashElem Fts3HashElem;
23
24/* A complete hash table is an instance of the following structure.
25** The internals of this structure are intended to be opaque -- client
26** code should not attempt to access or modify the fields of this structure
27** directly.  Change this structure only by using the routines below.
28** However, many of the "procedures" and "functions" for modifying and
29** accessing this structure are really macros, so we can't really make
30** this structure opaque.
31*/
32struct Fts3Hash {
33  char keyClass;          /* HASH_INT, _POINTER, _STRING, _BINARY */
34  char copyKey;           /* True if copy of key made on insert */
35  int count;              /* Number of entries in this table */
36  Fts3HashElem *first;    /* The first element of the array */
37  int htsize;             /* Number of buckets in the hash table */
38  struct _fts3ht {        /* the hash table */
39    int count;               /* Number of entries with this hash */
40    Fts3HashElem *chain;     /* Pointer to first entry with this hash */
41  } *ht;
42};
43
44/* Each element in the hash table is an instance of the following
45** structure.  All elements are stored on a single doubly-linked list.
46**
47** Again, this structure is intended to be opaque, but it can't really
48** be opaque because it is used by macros.
49*/
50struct Fts3HashElem {
51  Fts3HashElem *next, *prev; /* Next and previous elements in the table */
52  void *data;                /* Data associated with this element */
53  void *pKey; int nKey;      /* Key associated with this element */
54};
55
56/*
57** There are 2 different modes of operation for a hash table:
58**
59**   FTS3_HASH_STRING        pKey points to a string that is nKey bytes long
60**                           (including the null-terminator, if any).  Case
61**                           is respected in comparisons.
62**
63**   FTS3_HASH_BINARY        pKey points to binary data nKey bytes long.
64**                           memcmp() is used to compare keys.
65**
66** A copy of the key is made if the copyKey parameter to fts3HashInit is 1.
67*/
68#define FTS3_HASH_STRING    1
69#define FTS3_HASH_BINARY    2
70
71/*
72** Access routines.  To delete, insert a NULL pointer.
73*/
74void sqlite3Fts3HashInit(Fts3Hash *pNew, char keyClass, char copyKey);
75void *sqlite3Fts3HashInsert(Fts3Hash*, const void *pKey, int nKey, void *pData);
76void *sqlite3Fts3HashFind(const Fts3Hash*, const void *pKey, int nKey);
77void sqlite3Fts3HashClear(Fts3Hash*);
78Fts3HashElem *sqlite3Fts3HashFindElem(const Fts3Hash *, const void *, int);
79
80/*
81** Shorthand for the functions above
82*/
83#define fts3HashInit     sqlite3Fts3HashInit
84#define fts3HashInsert   sqlite3Fts3HashInsert
85#define fts3HashFind     sqlite3Fts3HashFind
86#define fts3HashClear    sqlite3Fts3HashClear
87#define fts3HashFindElem sqlite3Fts3HashFindElem
88
89/*
90** Macros for looping over all elements of a hash table.  The idiom is
91** like this:
92**
93**   Fts3Hash h;
94**   Fts3HashElem *p;
95**   ...
96**   for(p=fts3HashFirst(&h); p; p=fts3HashNext(p)){
97**     SomeStructure *pData = fts3HashData(p);
98**     // do something with pData
99**   }
100*/
101#define fts3HashFirst(H)  ((H)->first)
102#define fts3HashNext(E)   ((E)->next)
103#define fts3HashData(E)   ((E)->data)
104#define fts3HashKey(E)    ((E)->pKey)
105#define fts3HashKeysize(E) ((E)->nKey)
106
107/*
108** Number of entries in a hash table
109*/
110#define fts3HashCount(H)  ((H)->count)
111
112#endif /* _FTS3_HASH_H_ */
113