nsprpub/lib/ds/plhash.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
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  15  * The Original Code is the Netscape Portable Runtime (NSPR).
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  17  * The Initial Developer of the Original Code is
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  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef plhash_h___
  39 #define plhash_h___
  40 /*
  41  * API to portable hash table code.
  42  */
  43 #include <stdio.h>
  44 #include "prtypes.h"
  45
  46 PR_BEGIN_EXTERN_C
  47
  48 typedef struct PLHashEntry  PLHashEntry;
  49 typedef struct PLHashTable  PLHashTable;
  50 typedef PRUint32 PLHashNumber;
  51 #define PL_HASH_BITS 32  /* Number of bits in PLHashNumber */
  52 typedef PLHashNumber (PR_CALLBACK *PLHashFunction)(const void *key);
  53 typedef PRIntn (PR_CALLBACK *PLHashComparator)(const void *v1, const void *v2);
  54
  55 typedef PRIntn (PR_CALLBACK *PLHashEnumerator)(PLHashEntry *he, PRIntn i, void *arg);
  56
  57 /* Flag bits in PLHashEnumerator's return value */
  58 #define HT_ENUMERATE_NEXT       0       /* continue enumerating entries */
  59 #define HT_ENUMERATE_STOP       1       /* stop enumerating entries */
  60 #define HT_ENUMERATE_REMOVE     2       /* remove and free the current entry */
  61 #define HT_ENUMERATE_UNHASH     4       /* just unhash the current entry */
  62
  63 typedef struct PLHashAllocOps {
  64     void *              (PR_CALLBACK *allocTable)(void *pool, PRSize size);
  65     void                (PR_CALLBACK *freeTable)(void *pool, void *item);
  66     PLHashEntry *       (PR_CALLBACK *allocEntry)(void *pool, const void *key);
  67     void                (PR_CALLBACK *freeEntry)(void *pool, PLHashEntry *he, PRUintn flag);
  68 } PLHashAllocOps;
  69
  70 #define HT_FREE_VALUE   0               /* just free the entry's value */
  71 #define HT_FREE_ENTRY   1               /* free value and entire entry */
  72
  73 struct PLHashEntry {
  74     PLHashEntry         *next;          /* hash chain linkage */
  75     PLHashNumber        keyHash;        /* key hash function result */
  76     const void          *key;           /* ptr to opaque key */
  77     void                *value;         /* ptr to opaque value */
  78 };
  79
  80 struct PLHashTable {
  81     PLHashEntry         **buckets;      /* vector of hash buckets */
  82     PRUint32              nentries;       /* number of entries in table */
  83     PRUint32              shift;          /* multiplicative hash shift */
  84     PLHashFunction      keyHash;        /* key hash function */
  85     PLHashComparator    keyCompare;     /* key comparison function */
  86     PLHashComparator    valueCompare;   /* value comparison function */
  87     const PLHashAllocOps *allocOps;     /* allocation operations */
  88     void                *allocPriv;     /* allocation private data */
  89 #ifdef HASHMETER
  90     PRUint32              nlookups;       /* total number of lookups */
  91     PRUint32              nsteps;         /* number of hash chains traversed */
  92     PRUint32              ngrows;         /* number of table expansions */
  93     PRUint32              nshrinks;       /* number of table contractions */
  94 #endif
  95 };
  96
  97 /*
  98  * Create a new hash table.
  99  * If allocOps is null, use default allocator ops built on top of malloc().
 100  */
 101 PR_EXTERN(PLHashTable *)
 102 PL_NewHashTable(PRUint32 numBuckets, PLHashFunction keyHash,
 103                 PLHashComparator keyCompare, PLHashComparator valueCompare,
 104                 const PLHashAllocOps *allocOps, void *allocPriv);
 105
 106 PR_EXTERN(void)
 107 PL_HashTableDestroy(PLHashTable *ht);
 108
 109 /* Higher level access methods */
 110 PR_EXTERN(PLHashEntry *)
 111 PL_HashTableAdd(PLHashTable *ht, const void *key, void *value);
 112
 113 PR_EXTERN(PRBool)
 114 PL_HashTableRemove(PLHashTable *ht, const void *key);
 115
 116 PR_EXTERN(void *)
 117 PL_HashTableLookup(PLHashTable *ht, const void *key);
 118
 119 PR_EXTERN(void *)
 120 PL_HashTableLookupConst(PLHashTable *ht, const void *key);
 121
 122 PR_EXTERN(PRIntn)
 123 PL_HashTableEnumerateEntries(PLHashTable *ht, PLHashEnumerator f, void *arg);
 124
 125 /* General-purpose C string hash function. */
 126 PR_EXTERN(PLHashNumber)
 127 PL_HashString(const void *key);
 128
 129 /* Compare strings using strcmp(), return true if equal. */
 130 PR_EXTERN(PRIntn)
 131 PL_CompareStrings(const void *v1, const void *v2);
 132
 133 /* Stub function just returns v1 == v2 */
 134 PR_EXTERN(PRIntn)
 135 PL_CompareValues(const void *v1, const void *v2);
 136
 137 /* Low level access methods */
 138 PR_EXTERN(PLHashEntry **)
 139 PL_HashTableRawLookup(PLHashTable *ht, PLHashNumber keyHash, const void *key);
 140
 141 PR_EXTERN(PLHashEntry **)
 142 PL_HashTableRawLookupConst(PLHashTable *ht, PLHashNumber keyHash,
 143                            const void *key);
 144
 145 PR_EXTERN(PLHashEntry *)
 146 PL_HashTableRawAdd(PLHashTable *ht, PLHashEntry **hep, PLHashNumber keyHash,
 147                    const void *key, void *value);
 148
 149 PR_EXTERN(void)
 150 PL_HashTableRawRemove(PLHashTable *ht, PLHashEntry **hep, PLHashEntry *he);
 151
 152 /* This can be trivially implemented using PL_HashTableEnumerateEntries. */
 153 PR_EXTERN(PRIntn)
 154 PL_HashTableDump(PLHashTable *ht, PLHashEnumerator dump, FILE *fp);
 155
 156 PR_END_EXTERN_C
 157
 158 #endif /* plhash_h___ */