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Annotation of embedaddon/sqlite3/ext/fts1/ft_hash.h, revision 1.1.1.1

1.1       misho       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.  We've modified it slightly to serve as a standalone
                     14: ** hash table implementation for the full-text indexing module.
                     15: **
                     16: */
                     17: #ifndef _HASH_H_
                     18: #define _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;          /* 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:   void *(*xMalloc)(int);  /* malloc() function to use */
                     38:   void (*xFree)(void *);  /* free() function to use */
                     39:   int htsize;             /* Number of buckets in the hash table */
                     40:   struct _ht {            /* the hash table */
                     41:     int count;               /* Number of entries with this hash */
                     42:     HashElem *chain;         /* Pointer to first entry with this hash */
                     43:   } *ht;
                     44: };
                     45: 
                     46: /* Each element in the hash table is an instance of the following 
                     47: ** structure.  All elements are stored on a single doubly-linked list.
                     48: **
                     49: ** Again, this structure is intended to be opaque, but it can't really
                     50: ** be opaque because it is used by macros.
                     51: */
                     52: struct HashElem {
                     53:   HashElem *next, *prev;   /* Next and previous elements in the table */
                     54:   void *data;              /* Data associated with this element */
                     55:   void *pKey; int nKey;    /* Key associated with this element */
                     56: };
                     57: 
                     58: /*
                     59: ** There are 4 different modes of operation for a hash table:
                     60: **
                     61: **   HASH_INT         nKey is used as the key and pKey is ignored.
                     62: **
                     63: **   HASH_POINTER     pKey is used as the key and nKey is ignored.
                     64: **
                     65: **   HASH_STRING      pKey points to a string that is nKey bytes long
                     66: **                           (including the null-terminator, if any).  Case
                     67: **                           is respected in comparisons.
                     68: **
                     69: **   HASH_BINARY      pKey points to binary data nKey bytes long. 
                     70: **                           memcmp() is used to compare keys.
                     71: **
                     72: ** A copy of the key is made for HASH_STRING and HASH_BINARY
                     73: ** if the copyKey parameter to HashInit is 1.  
                     74: */
                     75: /* #define HASH_INT       1 // NOT USED */
                     76: /* #define HASH_POINTER   2 // NOT USED */
                     77: #define HASH_STRING    3
                     78: #define HASH_BINARY    4
                     79: 
                     80: /*
                     81: ** Access routines.  To delete, insert a NULL pointer.
                     82: */
                     83: void HashInit(Hash*, int keytype, int copyKey);
                     84: void *HashInsert(Hash*, const void *pKey, int nKey, void *pData);
                     85: void *HashFind(const Hash*, const void *pKey, int nKey);
                     86: void HashClear(Hash*);
                     87: 
                     88: /*
                     89: ** Macros for looping over all elements of a hash table.  The idiom is
                     90: ** like this:
                     91: **
                     92: **   Hash h;
                     93: **   HashElem *p;
                     94: **   ...
                     95: **   for(p=HashFirst(&h); p; p=HashNext(p)){
                     96: **     SomeStructure *pData = HashData(p);
                     97: **     // do something with pData
                     98: **   }
                     99: */
                    100: #define HashFirst(H)  ((H)->first)
                    101: #define HashNext(E)   ((E)->next)
                    102: #define HashData(E)   ((E)->data)
                    103: #define HashKey(E)    ((E)->pKey)
                    104: #define HashKeysize(E) ((E)->nKey)
                    105: 
                    106: /*
                    107: ** Number of entries in a hash table
                    108: */
                    109: #define HashCount(H)  ((H)->count)
                    110: 
                    111: #endif /* _HASH_H_ */