[205] | 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.
|
---|
| 14 | **
|
---|
| 15 | ** $Id: hash.h,v 1.6 2004/01/08 02:17:33 drh Exp $
|
---|
| 16 | */
|
---|
| 17 | #ifndef _SQLITE_HASH_H_
|
---|
| 18 | #define _SQLITE_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; /* SQLITE_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 | int htsize; /* Number of buckets in the hash table */
|
---|
| 38 | struct _ht { /* the hash table */
|
---|
| 39 | int count; /* Number of entries with this hash */
|
---|
| 40 | HashElem *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 HashElem {
|
---|
| 51 | HashElem *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 4 different modes of operation for a hash table:
|
---|
| 58 | **
|
---|
| 59 | ** SQLITE_HASH_INT nKey is used as the key and pKey is ignored.
|
---|
| 60 | **
|
---|
| 61 | ** SQLITE_HASH_POINTER pKey is used as the key and nKey is ignored.
|
---|
| 62 | **
|
---|
| 63 | ** SQLITE_HASH_STRING pKey points to a string that is nKey bytes long
|
---|
| 64 | ** (including the null-terminator, if any). Case
|
---|
| 65 | ** is ignored in comparisons.
|
---|
| 66 | **
|
---|
| 67 | ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long.
|
---|
| 68 | ** memcmp() is used to compare keys.
|
---|
| 69 | **
|
---|
| 70 | ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY
|
---|
| 71 | ** if the copyKey parameter to HashInit is 1.
|
---|
| 72 | */
|
---|
| 73 | #define SQLITE_HASH_INT 1
|
---|
| 74 | /* #define SQLITE_HASH_POINTER 2 // NOT USED */
|
---|
| 75 | #define SQLITE_HASH_STRING 3
|
---|
| 76 | #define SQLITE_HASH_BINARY 4
|
---|
| 77 |
|
---|
| 78 | /*
|
---|
| 79 | ** Access routines. To delete, insert a NULL pointer.
|
---|
| 80 | */
|
---|
| 81 | void sqliteHashInit(Hash*, int keytype, int copyKey);
|
---|
| 82 | void *sqliteHashInsert(Hash*, const void *pKey, int nKey, void *pData);
|
---|
| 83 | void *sqliteHashFind(const Hash*, const void *pKey, int nKey);
|
---|
| 84 | void sqliteHashClear(Hash*);
|
---|
| 85 |
|
---|
| 86 | /*
|
---|
| 87 | ** Macros for looping over all elements of a hash table. The idiom is
|
---|
| 88 | ** like this:
|
---|
| 89 | **
|
---|
| 90 | ** Hash h;
|
---|
| 91 | ** HashElem *p;
|
---|
| 92 | ** ...
|
---|
| 93 | ** for(p=sqliteHashFirst(&h); p; p=sqliteHashNext(p)){
|
---|
| 94 | ** SomeStructure *pData = sqliteHashData(p);
|
---|
| 95 | ** // do something with pData
|
---|
| 96 | ** }
|
---|
| 97 | */
|
---|
| 98 | #define sqliteHashFirst(H) ((H)->first)
|
---|
| 99 | #define sqliteHashNext(E) ((E)->next)
|
---|
| 100 | #define sqliteHashData(E) ((E)->data)
|
---|
| 101 | #define sqliteHashKey(E) ((E)->pKey)
|
---|
| 102 | #define sqliteHashKeysize(E) ((E)->nKey)
|
---|
| 103 |
|
---|
| 104 | /*
|
---|
| 105 | ** Number of entries in a hash table
|
---|
| 106 | */
|
---|
| 107 | #define sqliteHashCount(H) ((H)->count)
|
---|
| 108 |
|
---|
| 109 | #endif /* _SQLITE_HASH_H_ */
|
---|