modernc.org/cc@v1.0.1/v2/testdata/_sqlite/ext/fts2/fts2_hash.h (about)

     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_ */