third_party/sqlite/sqlite-src-3080704/ext/fts2/fts2_hash.h

   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 implementation
  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 _FTS2_HASH_H_
  18 #define _FTS2_HASH_H_
  19
  20 /* Forward declarations of structures. */
  21 typedef struct fts2Hash fts2Hash;
  22 typedef struct fts2HashElem fts2HashElem;
  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 fts2Hash {
  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   fts2HashElem *first;    /* The first element of the array */
  37   int htsize;             /* Number of buckets in the hash table */
  38   struct _fts2ht {        /* the hash table */
  39     int count;               /* Number of entries with this hash */
  40     fts2HashElem *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 fts2HashElem {
  51   fts2HashElem *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 2 different modes of operation for a hash table:
  58 **
  59 **   FTS2_HASH_STRING        pKey points to a string that is nKey bytes long
  60 **                           (including the null-terminator, if any).  Case
  61 **                           is respected in comparisons.
  62 **
  63 **   FTS2_HASH_BINARY        pKey points to binary data nKey bytes long.
  64 **                           memcmp() is used to compare keys.
  65 **
  66 ** A copy of the key is made if the copyKey parameter to fts2HashInit is 1.
  67 */
  68 #define FTS2_HASH_STRING    1
  69 #define FTS2_HASH_BINARY    2
  70
  71 /*
  72 ** Access routines.  To delete, insert a NULL pointer.
  73 */
  74 void sqlite3Fts2HashInit(fts2Hash*, int keytype, int copyKey);
  75 void *sqlite3Fts2HashInsert(fts2Hash*, const void *pKey, int nKey, void *pData);
  76 void *sqlite3Fts2HashFind(const fts2Hash*, const void *pKey, int nKey);
  77 void sqlite3Fts2HashClear(fts2Hash*);
  78
  79 /*
  80 ** Shorthand for the functions above
  81 */
  82 #define fts2HashInit   sqlite3Fts2HashInit
  83 #define fts2HashInsert sqlite3Fts2HashInsert
  84 #define fts2HashFind   sqlite3Fts2HashFind
  85 #define fts2HashClear  sqlite3Fts2HashClear
  86
  87 /*
  88 ** Macros for looping over all elements of a hash table.  The idiom is
  89 ** like this:
  90 **
  91 **   fts2Hash h;
  92 **   fts2HashElem *p;
  93 **   ...
  94 **   for(p=fts2HashFirst(&h); p; p=fts2HashNext(p)){
  95 **     SomeStructure *pData = fts2HashData(p);
  96 **     // do something with pData
  97 **   }
  98 */
  99 #define fts2HashFirst(H)  ((H)->first)
 100 #define fts2HashNext(E)   ((E)->next)
 101 #define fts2HashData(E)   ((E)->data)
 102 #define fts2HashKey(E)    ((E)->pKey)
 103 #define fts2HashKeysize(E) ((E)->nKey)
 104
 105 /*
 106 ** Number of entries in a hash table
 107 */
 108 #define fts2HashCount(H)  ((H)->count)
 109
 110 #endif /* _FTS2_HASH_H_ */