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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 implementation | |
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 _FTS2_HASH_H_ | |
18 #define _FTS2_HASH_H_ | |
19 | |
20 /* Forward declarations of structures. */ | |
21 typedef struct fts2Hash fts2Hash; | |
22 typedef struct fts2HashElem fts2HashElem; | |
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 */ | |
32 struct fts2Hash { | |
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 fts2HashElem *first; /* The first element of the array */ | |
37 int htsize; /* Number of buckets in the hash table */ | |
38 struct _fts2ht { /* the hash table */ | |
39 int count; /* Number of entries with this hash */ | |
40 fts2HashElem *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 */ | |
50 struct fts2HashElem { | |
51 fts2HashElem *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 ** FTS2_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 ** FTS2_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 fts2HashInit is 1. | |
67 */ | |
68 #define FTS2_HASH_STRING 1 | |
69 #define FTS2_HASH_BINARY 2 | |
70 | |
71 /* | |
72 ** Access routines. To delete, insert a NULL pointer. | |
73 */ | |
74 void sqlite3Fts2HashInit(fts2Hash*, int keytype, int copyKey); | |
75 void *sqlite3Fts2HashInsert(fts2Hash*, const void *pKey, int nKey, void *pData); | |
76 void *sqlite3Fts2HashFind(const fts2Hash*, const void *pKey, int nKey); | |
77 void sqlite3Fts2HashClear(fts2Hash*); | |
78 | |
79 /* | |
80 ** Shorthand for the functions above | |
81 */ | |
82 #define fts2HashInit sqlite3Fts2HashInit | |
83 #define fts2HashInsert sqlite3Fts2HashInsert | |
84 #define fts2HashFind sqlite3Fts2HashFind | |
85 #define fts2HashClear sqlite3Fts2HashClear | |
86 | |
87 /* | |
88 ** Macros for looping over all elements of a hash table. The idiom is | |
89 ** like this: | |
90 ** | |
91 ** fts2Hash h; | |
92 ** fts2HashElem *p; | |
93 ** ... | |
94 ** for(p=fts2HashFirst(&h); p; p=fts2HashNext(p)){ | |
95 ** SomeStructure *pData = fts2HashData(p); | |
96 ** // do something with pData | |
97 ** } | |
98 */ | |
99 #define fts2HashFirst(H) ((H)->first) | |
100 #define fts2HashNext(E) ((E)->next) | |
101 #define fts2HashData(E) ((E)->data) | |
102 #define fts2HashKey(E) ((E)->pKey) | |
103 #define fts2HashKeysize(E) ((E)->nKey) | |
104 | |
105 /* | |
106 ** Number of entries in a hash table | |
107 */ | |
108 #define fts2HashCount(H) ((H)->count) | |
109 | |
110 #endif /* _FTS2_HASH_H_ */ | |
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