/* ** 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. ** ** $Id: hash.h,v 1.1.1.1 2006/02/03 20:35:12 hoganrobert Exp $ */ #ifndef _SQLITE_HASH_H_ #define _SQLITE_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; /* SQLITE_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 */ 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: ** ** SQLITE_HASH_INT nKey is used as the key and pKey is ignored. ** ** SQLITE_HASH_POINTER pKey is used as the key and nKey is ignored. ** ** SQLITE_HASH_STRING pKey points to a string that is nKey bytes long ** (including the null-terminator, if any). Case ** is ignored in comparisons. ** ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. ** memcmp() is used to compare keys. ** ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY ** if the copyKey parameter to HashInit is 1. */ /* #define SQLITE_HASH_INT 1 // NOT USED */ /* #define SQLITE_HASH_POINTER 2 // NOT USED */ #define SQLITE_HASH_STRING 3 #define SQLITE_HASH_BINARY 4 /* ** Access routines. To delete, insert a NULL pointer. */ void sqlite3HashInit(Hash*, int keytype, int copyKey); void *sqlite3HashInsert(Hash*, const void *pKey, int nKey, void *pData); void *sqlite3HashFind(const Hash*, const void *pKey, int nKey); void sqlite3HashClear(Hash*); /* ** Macros for looping over all elements of a hash table. The idiom is ** like this: ** ** Hash h; ** HashElem *p; ** ... ** for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){ ** SomeStructure *pData = sqliteHashData(p); ** // do something with pData ** } */ #define sqliteHashFirst(H) ((H)->first) #define sqliteHashNext(E) ((E)->next) #define sqliteHashData(E) ((E)->data) #define sqliteHashKey(E) ((E)->pKey) #define sqliteHashKeysize(E) ((E)->nKey) /* ** Number of entries in a hash table */ #define sqliteHashCount(H) ((H)->count) #endif /* _SQLITE_HASH_H_ */