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 _HASH_H_ 18 #define _HASH_H_ 19 20 /* Forward declarations of structures. */ 21 typedef struct Hash Hash; 22 typedef struct HashElem HashElem; 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 Hash { 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 HashElem *first; /* The first element of the array */ 37 void *(*xMalloc)(int); /* malloc() function to use */ 38 void (*xFree)(void *); /* free() function to use */ 39 int htsize; /* Number of buckets in the hash table */ 40 struct _ht { /* the hash table */ 41 int count; /* Number of entries with this hash */ 42 HashElem *chain; /* Pointer to first entry with this hash */ 43 } *ht; 44 }; 45 46 /* Each element in the hash table is an instance of the following 47 ** structure. All elements are stored on a single doubly-linked list. 48 ** 49 ** Again, this structure is intended to be opaque, but it can't really 50 ** be opaque because it is used by macros. 51 */ 52 struct HashElem { 53 HashElem *next, *prev; /* Next and previous elements in the table */ 54 void *data; /* Data associated with this element */ 55 void *pKey; int nKey; /* Key associated with this element */ 56 }; 57 58 /* 59 ** There are 4 different modes of operation for a hash table: 60 ** 61 ** HASH_INT nKey is used as the key and pKey is ignored. 62 ** 63 ** HASH_POINTER pKey is used as the key and nKey is ignored. 64 ** 65 ** HASH_STRING pKey points to a string that is nKey bytes long 66 ** (including the null-terminator, if any). Case 67 ** is respected in comparisons. 68 ** 69 ** HASH_BINARY pKey points to binary data nKey bytes long. 70 ** memcmp() is used to compare keys. 71 ** 72 ** A copy of the key is made for HASH_STRING and HASH_BINARY 73 ** if the copyKey parameter to HashInit is 1. 74 */ 75 /* #define HASH_INT 1 // NOT USED */ 76 /* #define HASH_POINTER 2 // NOT USED */ 77 #define HASH_STRING 3 78 #define HASH_BINARY 4 79 80 /* 81 ** Access routines. To delete, insert a NULL pointer. 82 */ 83 void HashInit(Hash*, int keytype, int copyKey); 84 void *HashInsert(Hash*, const void *pKey, int nKey, void *pData); 85 void *HashFind(const Hash*, const void *pKey, int nKey); 86 void HashClear(Hash*); 87 88 /* 89 ** Macros for looping over all elements of a hash table. The idiom is 90 ** like this: 91 ** 92 ** Hash h; 93 ** HashElem *p; 94 ** ... 95 ** for(p=HashFirst(&h); p; p=HashNext(p)){ 96 ** SomeStructure *pData = HashData(p); 97 ** // do something with pData 98 ** } 99 */ 100 #define HashFirst(H) ((H)->first) 101 #define HashNext(E) ((E)->next) 102 #define HashData(E) ((E)->data) 103 #define HashKey(E) ((E)->pKey) 104 #define HashKeysize(E) ((E)->nKey) 105 106 /* 107 ** Number of entries in a hash table 108 */ 109 #define HashCount(H) ((H)->count) 110 111 #endif /* _HASH_H_ */ 112
