| /* |
| ** 2001 September 22 |
| ** |
| ** The author disclaims copyright to this source code. In place of |
| ** a legal notice, here is a blessing: |
| ** |
| ** May you do good and not evil. |
| ** May you find forgiveness for yourself and forgive others. |
| ** May you share freely, never taking more than you give. |
| ** |
| ************************************************************************* |
| ** This is the header file for the generic hash-table implemenation |
| ** used in SQLite. We've modified it slightly to serve as a standalone |
| ** hash table implementation for the full-text indexing module. |
| ** |
| */ |
| #ifndef _HASH_H_ |
| #define _HASH_H_ |
| |
| /* Forward declarations of structures. */ |
| typedef struct Hash Hash; |
| typedef struct HashElem HashElem; |
| |
| /* A complete hash table is an instance of the following structure. |
| ** The internals of this structure are intended to be opaque -- client |
| ** code should not attempt to access or modify the fields of this structure |
| ** directly. Change this structure only by using the routines below. |
| ** However, many of the "procedures" and "functions" for modifying and |
| ** accessing this structure are really macros, so we can't really make |
| ** this structure opaque. |
| */ |
| struct Hash { |
| char keyClass; /* HASH_INT, _POINTER, _STRING, _BINARY */ |
| char copyKey; /* True if copy of key made on insert */ |
| int count; /* Number of entries in this table */ |
| HashElem *first; /* The first element of the array */ |
| void *(*xMalloc)(int); /* malloc() function to use */ |
| void (*xFree)(void *); /* free() function to use */ |
| int htsize; /* Number of buckets in the hash table */ |
| struct _ht { /* the hash table */ |
| int count; /* Number of entries with this hash */ |
| HashElem *chain; /* Pointer to first entry with this hash */ |
| } *ht; |
| }; |
| |
| /* Each element in the hash table is an instance of the following |
| ** structure. All elements are stored on a single doubly-linked list. |
| ** |
| ** Again, this structure is intended to be opaque, but it can't really |
| ** be opaque because it is used by macros. |
| */ |
| struct HashElem { |
| HashElem *next, *prev; /* Next and previous elements in the table */ |
| void *data; /* Data associated with this element */ |
| void *pKey; int nKey; /* Key associated with this element */ |
| }; |
| |
| /* |
| ** There are 4 different modes of operation for a hash table: |
| ** |
| ** HASH_INT nKey is used as the key and pKey is ignored. |
| ** |
| ** HASH_POINTER pKey is used as the key and nKey is ignored. |
| ** |
| ** HASH_STRING pKey points to a string that is nKey bytes long |
| ** (including the null-terminator, if any). Case |
| ** is respected in comparisons. |
| ** |
| ** HASH_BINARY pKey points to binary data nKey bytes long. |
| ** memcmp() is used to compare keys. |
| ** |
| ** A copy of the key is made for HASH_STRING and HASH_BINARY |
| ** if the copyKey parameter to HashInit is 1. |
| */ |
| /* #define HASH_INT 1 // NOT USED */ |
| /* #define HASH_POINTER 2 // NOT USED */ |
| #define HASH_STRING 3 |
| #define HASH_BINARY 4 |
| |
| /* |
| ** Access routines. To delete, insert a NULL pointer. |
| */ |
| void HashInit(Hash*, int keytype, int copyKey); |
| void *HashInsert(Hash*, const void *pKey, int nKey, void *pData); |
| void *HashFind(const Hash*, const void *pKey, int nKey); |
| void HashClear(Hash*); |
| |
| /* |
| ** Macros for looping over all elements of a hash table. The idiom is |
| ** like this: |
| ** |
| ** Hash h; |
| ** HashElem *p; |
| ** ... |
| ** for(p=HashFirst(&h); p; p=HashNext(p)){ |
| ** SomeStructure *pData = HashData(p); |
| ** // do something with pData |
| ** } |
| */ |
| #define HashFirst(H) ((H)->first) |
| #define HashNext(E) ((E)->next) |
| #define HashData(E) ((E)->data) |
| #define HashKey(E) ((E)->pKey) |
| #define HashKeysize(E) ((E)->nKey) |
| |
| /* |
| ** Number of entries in a hash table |
| */ |
| #define HashCount(H) ((H)->count) |
| |
| #endif /* _HASH_H_ */ |