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. */ 21 typedef struct Fts3Hash Fts3Hash; 22 typedef 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 */ 32 struct 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 */ 50 struct 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 */ 74 void sqlite3Fts3HashInit(Fts3Hash *pNew, char keyClass, char copyKey); 75 void *sqlite3Fts3HashInsert(Fts3Hash*, const void *pKey, int nKey, void *pData); 76 void *sqlite3Fts3HashFind(const Fts3Hash*, const void *pKey, int nKey); 77 void sqlite3Fts3HashClear(Fts3Hash*); 78 Fts3HashElem *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