ext/fts1/fts1_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 _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_ */