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      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 _FTS1_HASH_H_
     18 #define _FTS1_HASH_H_
     19 
     20 /* Forward declarations of structures. */
     21 typedef struct fts1Hash fts1Hash;
     22 typedef struct fts1HashElem fts1HashElem;
     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 fts1Hash {
     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   fts1HashElem *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 _fts1ht {        /* the hash table */
     41     int count;               /* Number of entries with this hash */
     42     fts1HashElem *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 fts1HashElem {
     53   fts1HashElem *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 2 different modes of operation for a hash table:
     60 **
     61 **   FTS1_HASH_STRING        pKey points to a string that is nKey bytes long
     62 **                           (including the null-terminator, if any).  Case
     63 **                           is respected in comparisons.
     64 **
     65 **   FTS1_HASH_BINARY        pKey points to binary data nKey bytes long.
     66 **                           memcmp() is used to compare keys.
     67 **
     68 ** A copy of the key is made if the copyKey parameter to fts1HashInit is 1.
     69 */
     70 #define FTS1_HASH_STRING    1
     71 #define FTS1_HASH_BINARY    2
     72 
     73 /*
     74 ** Access routines.  To delete, insert a NULL pointer.
     75 */
     76 void sqlite3Fts1HashInit(fts1Hash*, int keytype, int copyKey);
     77 void *sqlite3Fts1HashInsert(fts1Hash*, const void *pKey, int nKey, void *pData);
     78 void *sqlite3Fts1HashFind(const fts1Hash*, const void *pKey, int nKey);
     79 void sqlite3Fts1HashClear(fts1Hash*);
     80 
     81 /*
     82 ** Shorthand for the functions above
     83 */
     84 #define fts1HashInit   sqlite3Fts1HashInit
     85 #define fts1HashInsert sqlite3Fts1HashInsert
     86 #define fts1HashFind   sqlite3Fts1HashFind
     87 #define fts1HashClear  sqlite3Fts1HashClear
     88 
     89 /*
     90 ** Macros for looping over all elements of a hash table.  The idiom is
     91 ** like this:
     92 **
     93 **   fts1Hash h;
     94 **   fts1HashElem *p;
     95 **   ...
     96 **   for(p=fts1HashFirst(&h); p; p=fts1HashNext(p)){
     97 **     SomeStructure *pData = fts1HashData(p);
     98 **     // do something with pData
     99 **   }
    100 */
    101 #define fts1HashFirst(H)  ((H)->first)
    102 #define fts1HashNext(E)   ((E)->next)
    103 #define fts1HashData(E)   ((E)->data)
    104 #define fts1HashKey(E)    ((E)->pKey)
    105 #define fts1HashKeysize(E) ((E)->nKey)
    106 
    107 /*
    108 ** Number of entries in a hash table
    109 */
    110 #define fts1HashCount(H)  ((H)->count)
    111 
    112 #endif /* _FTS1_HASH_H_ */
    113