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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 17:28:19 +0000 |
commit | 18657a960e125336f704ea058e25c27bd3900dcb (patch) | |
tree | 17b438b680ed45a996d7b59951e6aa34023783f2 /src/hash.h | |
parent | Initial commit. (diff) | |
download | sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.tar.xz sqlite3-18657a960e125336f704ea058e25c27bd3900dcb.zip |
Adding upstream version 3.40.1.upstream/3.40.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/hash.h')
-rw-r--r-- | src/hash.h | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/src/hash.h b/src/hash.h new file mode 100644 index 0000000..3f491e4 --- /dev/null +++ b/src/hash.h @@ -0,0 +1,96 @@ +/* +** 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 implementation +** used in SQLite. +*/ +#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, some of the "procedures" and "functions" for modifying and +** accessing this structure are really macros, so we can't really make +** this structure opaque. +** +** All elements of the hash table are on a single doubly-linked list. +** Hash.first points to the head of this list. +** +** There are Hash.htsize buckets. Each bucket points to a spot in +** the global doubly-linked list. The contents of the bucket are the +** element pointed to plus the next _ht.count-1 elements in the list. +** +** Hash.htsize and Hash.ht may be zero. In that case lookup is done +** by a linear search of the global list. For small tables, the +** Hash.ht table is never allocated because if there are few elements +** in the table, it is faster to do a linear search than to manage +** the hash table. +*/ +struct Hash { + unsigned int htsize; /* Number of buckets in the hash table */ + unsigned int count; /* Number of entries in this table */ + HashElem *first; /* The first element of the array */ + struct _ht { /* the hash table */ + unsigned 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 */ + const char *pKey; /* Key associated with this element */ +}; + +/* +** Access routines. To delete, insert a NULL pointer. +*/ +void sqlite3HashInit(Hash*); +void *sqlite3HashInsert(Hash*, const char *pKey, void *pData); +void *sqlite3HashFind(const Hash*, const char *pKey); +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) // NOT USED */ +/* #define sqliteHashKeysize(E) ((E)->nKey) // NOT USED */ + +/* +** Number of entries in a hash table +*/ +#define sqliteHashCount(H) ((H)->count) + +#endif /* SQLITE_HASH_H */ |