diff options
Diffstat (limited to 'src/sqlite/hash.h')
| -rw-r--r-- | src/sqlite/hash.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/src/sqlite/hash.h b/src/sqlite/hash.h new file mode 100644 index 0000000..43c6b09 --- /dev/null +++ b/src/sqlite/hash.h @@ -0,0 +1,109 @@ +/* +** 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_ */ |