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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 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 _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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