modernc.org/cc@v1.0.1/v2/testdata/_sqlite/ext/fts1/ft_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 _HASH_H_
    18  #define _HASH_H_
    19  
    20  /* Forward declarations of structures. */
    21  typedef struct Hash Hash;
    22  typedef struct HashElem HashElem;
    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 Hash {
    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    HashElem *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 _ht {            /* the hash table */
    41      int count;               /* Number of entries with this hash */
    42      HashElem *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 HashElem {
    53    HashElem *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 4 different modes of operation for a hash table:
    60  **
    61  **   HASH_INT         nKey is used as the key and pKey is ignored.
    62  **
    63  **   HASH_POINTER     pKey is used as the key and nKey is ignored.
    64  **
    65  **   HASH_STRING      pKey points to a string that is nKey bytes long
    66  **                           (including the null-terminator, if any).  Case
    67  **                           is respected in comparisons.
    68  **
    69  **   HASH_BINARY      pKey points to binary data nKey bytes long. 
    70  **                           memcmp() is used to compare keys.
    71  **
    72  ** A copy of the key is made for HASH_STRING and HASH_BINARY
    73  ** if the copyKey parameter to HashInit is 1.  
    74  */
    75  /* #define HASH_INT       1 // NOT USED */
    76  /* #define HASH_POINTER   2 // NOT USED */
    77  #define HASH_STRING    3
    78  #define HASH_BINARY    4
    79  
    80  /*
    81  ** Access routines.  To delete, insert a NULL pointer.
    82  */
    83  void HashInit(Hash*, int keytype, int copyKey);
    84  void *HashInsert(Hash*, const void *pKey, int nKey, void *pData);
    85  void *HashFind(const Hash*, const void *pKey, int nKey);
    86  void HashClear(Hash*);
    87  
    88  /*
    89  ** Macros for looping over all elements of a hash table.  The idiom is
    90  ** like this:
    91  **
    92  **   Hash h;
    93  **   HashElem *p;
    94  **   ...
    95  **   for(p=HashFirst(&h); p; p=HashNext(p)){
    96  **     SomeStructure *pData = HashData(p);
    97  **     // do something with pData
    98  **   }
    99  */
   100  #define HashFirst(H)  ((H)->first)
   101  #define HashNext(E)   ((E)->next)
   102  #define HashData(E)   ((E)->data)
   103  #define HashKey(E)    ((E)->pKey)
   104  #define HashKeysize(E) ((E)->nKey)
   105  
   106  /*
   107  ** Number of entries in a hash table
   108  */
   109  #define HashCount(H)  ((H)->count)
   110  
   111  #endif /* _HASH_H_ */