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00001 /* 00002 ** 2001 September 22 00003 ** 00004 ** The author disclaims copyright to this source code. In place of 00005 ** a legal notice, here is a blessing: 00006 ** 00007 ** May you do good and not evil. 00008 ** May you find forgiveness for yourself and forgive others. 00009 ** May you share freely, never taking more than you give. 00010 ** 00011 ************************************************************************* 00012 ** This is the header file for the generic hash-table implemenation 00013 ** used in SQLite. 00014 ** 00015 ** $Id: qt/hash.h 3.3.8 edited Mar 30 2004 $ 00016 */ 00017 #ifndef _SQLITE_HASH_H_ 00018 #define _SQLITE_HASH_H_ 00019 00020 /* Forward declarations of structures. */ 00021 typedef struct Hash Hash; 00022 typedef struct HashElem HashElem; 00023 00024 /* A complete hash table is an instance of the following structure. 00025 ** The internals of this structure are intended to be opaque -- client 00026 ** code should not attempt to access or modify the fields of this structure 00027 ** directly. Change this structure only by using the routines below. 00028 ** However, many of the "procedures" and "functions" for modifying and 00029 ** accessing this structure are really macros, so we can't really make 00030 ** this structure opaque. 00031 */ 00032 struct Hash { 00033 char keyClass; /* SQLITE_HASH_INT, _POINTER, _STRING, _BINARY */ 00034 char copyKey; /* True if copy of key made on insert */ 00035 int count; /* Number of entries in this table */ 00036 HashElem *first; /* The first element of the array */ 00037 int htsize; /* Number of buckets in the hash table */ 00038 struct _ht { /* the hash table */ 00039 int count; /* Number of entries with this hash */ 00040 HashElem *chain; /* Pointer to first entry with this hash */ 00041 } *ht; 00042 }; 00043 00044 /* Each element in the hash table is an instance of the following 00045 ** structure. All elements are stored on a single doubly-linked list. 00046 ** 00047 ** Again, this structure is intended to be opaque, but it can't really 00048 ** be opaque because it is used by macros. 00049 */ 00050 struct HashElem { 00051 HashElem *next, *prev; /* Next and previous elements in the table */ 00052 void *data; /* Data associated with this element */ 00053 void *pKey; int nKey; /* Key associated with this element */ 00054 }; 00055 00056 /* 00057 ** There are 4 different modes of operation for a hash table: 00058 ** 00059 ** SQLITE_HASH_INT nKey is used as the key and pKey is ignored. 00060 ** 00061 ** SQLITE_HASH_POINTER pKey is used as the key and nKey is ignored. 00062 ** 00063 ** SQLITE_HASH_STRING pKey points to a string that is nKey bytes long 00064 ** (including the null-terminator, if any). Case 00065 ** is ignored in comparisons. 00066 ** 00067 ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. 00068 ** memcmp() is used to compare keys. 00069 ** 00070 ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY 00071 ** if the copyKey parameter to HashInit is 1. 00072 */ 00073 #define SQLITE_HASH_INT 1 00074 /* #define SQLITE_HASH_POINTER 2 // NOT USED */ 00075 #define SQLITE_HASH_STRING 3 00076 #define SQLITE_HASH_BINARY 4 00077 00078 /* 00079 ** Access routines. To delete, insert a NULL pointer. 00080 */ 00081 void sqliteHashInit(Hash*, int keytype, int copyKey); 00082 void *sqliteHashInsert(Hash*, const void *pKey, int nKey, void *pData); 00083 void *sqliteHashFind(const Hash*, const void *pKey, int nKey); 00084 void sqliteHashClear(Hash*); 00085 00086 /* 00087 ** Macros for looping over all elements of a hash table. The idiom is 00088 ** like this: 00089 ** 00090 ** Hash h; 00091 ** HashElem *p; 00092 ** ... 00093 ** for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){ 00094 ** SomeStructure *pData = sqliteHashData(p); 00095 ** // do something with pData 00096 ** } 00097 */ 00098 #define sqliteHashFirst(H) ((H)->first) 00099 #define sqliteHashNext(E) ((E)->next) 00100 #define sqliteHashData(E) ((E)->data) 00101 #define sqliteHashKey(E) ((E)->pKey) 00102 #define sqliteHashKeysize(E) ((E)->nKey) 00103 00104 /* 00105 ** Number of entries in a hash table 00106 */ 00107 #define sqliteHashCount(H) ((H)->count) 00108 00109 #endif /* _SQLITE_HASH_H_ */