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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 _FTS3_HASH_H_
   18: #define _FTS3_HASH_H_
   19: 
   20: /* Forward declarations of structures. */
   21: typedef struct Fts3Hash Fts3Hash;
   22: typedef struct Fts3HashElem Fts3HashElem;
   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 Fts3Hash {
   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:   Fts3HashElem *first;    /* The first element of the array */
   37:   int htsize;             /* Number of buckets in the hash table */
   38:   struct _fts3ht {        /* the hash table */
   39:     int count;               /* Number of entries with this hash */
   40:     Fts3HashElem *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 Fts3HashElem {
   51:   Fts3HashElem *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: **   FTS3_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: **   FTS3_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 fts3HashInit is 1.  
   67: */
   68: #define FTS3_HASH_STRING    1
   69: #define FTS3_HASH_BINARY    2
   70: 
   71: /*
   72: ** Access routines.  To delete, insert a NULL pointer.
   73: */
   74: void sqlite3Fts3HashInit(Fts3Hash *pNew, char keyClass, char copyKey);
   75: void *sqlite3Fts3HashInsert(Fts3Hash*, const void *pKey, int nKey, void *pData);
   76: void *sqlite3Fts3HashFind(const Fts3Hash*, const void *pKey, int nKey);
   77: void sqlite3Fts3HashClear(Fts3Hash*);
   78: Fts3HashElem *sqlite3Fts3HashFindElem(const Fts3Hash *, const void *, int);
   79: 
   80: /*
   81: ** Shorthand for the functions above
   82: */
   83: #define fts3HashInit     sqlite3Fts3HashInit
   84: #define fts3HashInsert   sqlite3Fts3HashInsert
   85: #define fts3HashFind     sqlite3Fts3HashFind
   86: #define fts3HashClear    sqlite3Fts3HashClear
   87: #define fts3HashFindElem sqlite3Fts3HashFindElem
   88: 
   89: /*
   90: ** Macros for looping over all elements of a hash table.  The idiom is
   91: ** like this:
   92: **
   93: **   Fts3Hash h;
   94: **   Fts3HashElem *p;
   95: **   ...
   96: **   for(p=fts3HashFirst(&h); p; p=fts3HashNext(p)){
   97: **     SomeStructure *pData = fts3HashData(p);
   98: **     // do something with pData
   99: **   }
  100: */
  101: #define fts3HashFirst(H)  ((H)->first)
  102: #define fts3HashNext(E)   ((E)->next)
  103: #define fts3HashData(E)   ((E)->data)
  104: #define fts3HashKey(E)    ((E)->pKey)
  105: #define fts3HashKeysize(E) ((E)->nKey)
  106: 
  107: /*
  108: ** Number of entries in a hash table
  109: */
  110: #define fts3HashCount(H)  ((H)->count)
  111: 
  112: #endif /* _FTS3_HASH_H_ */