runtime/hashtable2.h

   1 /*
   2  * Copyright (c) 1999-2006 Apple Inc.  All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24     hashtable2.h
  25     Scalable hash table.
  26     Copyright 1989-1996 NeXT Software, Inc.
  27 */
  28
  29 #ifndef _OBJC_LITTLE_HASHTABLE_H_
  30 #define _OBJC_LITTLE_HASHTABLE_H_
  31
  32 #ifndef _OBJC_PRIVATE_H_
  33 #warning The API in this header is obsoleted by NSHashtable.h
  34 #endif
  35
  36 #include <objc/objc.h>
  37 #include <stdint.h>
  38 #include <TargetConditionals.h>
  39
  40 /*************************************************************************
  41  *      Hash tables of arbitrary data
  42  *************************************************************************/
  43
  44 /* This module allows hashing of arbitrary data.  Such data must be pointers or integers, and client is responsible for allocating/deallocating this data.  A deallocation call-back is provided.
  45 The objective C class HashTable is preferred when dealing with (key, values) associations because it is easier to use in that situation.
  46 As well-behaved scalable data structures, hash tables double in size when they start becoming full, thus guaranteeing both average constant time access and linear size. */
  47
  48 typedef struct {
  49     uintptr_t   (*hash)(const void *info, const void *data);
  50     int         (*isEqual)(const void *info, const void *data1, const void *data2);
  51     void        (*free)(const void *info, void *data);
  52     int         style; /* reserved for future expansion; currently 0 */
  53     } NXHashTablePrototype;
  54
  55 /* the info argument allows a certain generality, such as freeing according to some owner information */
  56 /* invariants assumed by the implementation:
  57         1 - data1 = data2 => hash(data1) = hash(data2)
  58             when data varies over time, hash(data) must remain invariant
  59                     e.g. if data hashes over a string key, the string must not be changed
  60         2- isEqual (data1, data2) => data1= data2
  61  */
  62
  63 typedef struct {
  64     const NXHashTablePrototype  *prototype;
  65     unsigned                    count;
  66     unsigned                    nbBuckets;
  67     void                        *buckets;
  68     const void                  *info;
  69    } NXHashTable;
  70     /* private data structure; may change */
  71
  72 OBJC_EXPORT NXHashTable *NXCreateHashTableFromZone (NXHashTablePrototype prototype, unsigned capacity, const void *info, void *z);
  73 OBJC_EXPORT NXHashTable *NXCreateHashTable (NXHashTablePrototype prototype, unsigned capacity, const void *info);
  74     /* if hash is 0, pointer hash is assumed */
  75     /* if isEqual is 0, pointer equality is assumed */
  76     /* if free is 0, elements are not freed */
  77     /* capacity is only a hint; 0 creates a small table */
  78     /* info allows call backs to be very general */
  79
  80 OBJC_EXPORT void NXFreeHashTable (NXHashTable *table);
  81     /* calls free for each data, and recovers table */
  82
  83 OBJC_EXPORT void NXEmptyHashTable (NXHashTable *table);
  84     /* does not deallocate table nor data; keeps current capacity */
  85
  86 OBJC_EXPORT void NXResetHashTable (NXHashTable *table);
  87     /* frees each entry; keeps current capacity */
  88
  89 OBJC_EXPORT BOOL NXCompareHashTables (NXHashTable *table1, NXHashTable *table2);
  90     /* Returns YES if the two sets are equal (each member of table1 in table2, and table have same size) */
  91
  92 OBJC_EXPORT NXHashTable *NXCopyHashTable (NXHashTable *table);
  93     /* makes a fresh table, copying data pointers, not data itself.  */
  94
  95 OBJC_EXPORT unsigned NXCountHashTable (NXHashTable *table);
  96     /* current number of data in table */
  97
  98 OBJC_EXPORT int NXHashMember (NXHashTable *table, const void *data);
  99     /* returns non-0 iff data is present in table.
 100     Example of use when the hashed data is a struct containing the key,
 101     and when the callee only has a key:
 102         MyStruct        pseudo;
 103         pseudo.key = myKey;
 104         return NXHashMember (myTable, &pseudo)
 105     */
 106
 107 OBJC_EXPORT void *NXHashGet (NXHashTable *table, const void *data);
 108     /* return original table data or NULL.
 109     Example of use when the hashed data is a struct containing the key,
 110     and when the callee only has a key:
 111         MyStruct        pseudo;
 112         MyStruct        *original;
 113         pseudo.key = myKey;
 114         original = NXHashGet (myTable, &pseudo)
 115     */
 116
 117 OBJC_EXPORT void *NXHashInsert (NXHashTable *table, const void *data);
 118     /* previous data or NULL is returned. */
 119
 120 OBJC_EXPORT void *NXHashInsertIfAbsent (NXHashTable *table, const void *data);
 121     /* If data already in table, returns the one in table
 122     else adds argument to table and returns argument. */
 123
 124 OBJC_EXPORT void *NXHashRemove (NXHashTable *table, const void *data);
 125     /* previous data or NULL is returned */
 126
 127 /* Iteration over all elements of a table consists in setting up an iteration state and then to progress until all entries have been visited.  An example of use for counting elements in a table is:
 128     unsigned    count = 0;
 129     MyData      *data;
 130     NXHashState state = NXInitHashState(table);
 131     while (NXNextHashState(table, &state, &data)) {
 132         count++;
 133     }
 134 */
 135
 136 typedef struct {int i; int j;} NXHashState;
 137     /* callers should not rely on actual contents of the struct */
 138
 139 OBJC_EXPORT NXHashState NXInitHashState(NXHashTable *table);
 140
 141 OBJC_EXPORT int NXNextHashState(NXHashTable *table, NXHashState *state, void **data);
 142     /* returns 0 when all elements have been visited */
 143
 144 /*************************************************************************
 145  *      Conveniences for writing hash, isEqual and free functions
 146  *      and common prototypes
 147  *************************************************************************/
 148
 149 OBJC_EXPORT uintptr_t NXPtrHash(const void *info, const void *data);
 150     /* scrambles the address bits; info unused */
 151 OBJC_EXPORT uintptr_t NXStrHash(const void *info, const void *data);
 152     /* string hashing; info unused */
 153 OBJC_EXPORT int NXPtrIsEqual(const void *info, const void *data1, const void *data2);
 154     /* pointer comparison; info unused */
 155 OBJC_EXPORT int NXStrIsEqual(const void *info, const void *data1, const void *data2);
 156     /* string comparison; NULL ok; info unused */
 157 OBJC_EXPORT void NXNoEffectFree(const void *info, void *data);
 158     /* no effect; info unused */
 159 OBJC_EXPORT void NXReallyFree(const void *info, void *data);
 160     /* frees it; info unused */
 161
 162 /* The two following prototypes are useful for manipulating set of pointers or set of strings; For them free is defined as NXNoEffectFree */
 163 OBJC_EXPORT const NXHashTablePrototype NXPtrPrototype;
 164     /* prototype when data is a pointer (void *) */
 165 OBJC_EXPORT const NXHashTablePrototype NXStrPrototype;
 166     /* prototype when data is a string (char *) */
 167
 168 /* following prototypes help describe mappings where the key is the first element of a struct and is either a pointer or a string.
 169 For example NXStrStructKeyPrototype can be used to hash pointers to Example, where Example is:
 170         typedef struct {
 171             char        *key;
 172             int         data1;
 173             ...
 174             } Example
 175
 176 For the following prototypes, free is defined as NXReallyFree.
 177  */
 178 OBJC_EXPORT const NXHashTablePrototype NXPtrStructKeyPrototype;
 179 OBJC_EXPORT const NXHashTablePrototype NXStrStructKeyPrototype;
 180
 181
 182 #if !__OBJC2__  &&  !TARGET_OS_WIN32
 183
 184 /*************************************************************************
 185  *      Unique strings and buffers
 186  *************************************************************************/
 187
 188 /* Unique strings allows C users to enjoy the benefits of Lisp's atoms:
 189 A unique string is a string that is allocated once for all (never de-allocated) and that has only one representant (thus allowing comparison with == instead of strcmp).  A unique string should never be modified (and in fact some memory protection is done to ensure that).  In order to more explicitly insist on the fact that the string has been uniqued, a synonym of (const char *) has been added, NXAtom. */
 190
 191 typedef const char *NXAtom;
 192
 193 OBJC_EXPORT NXAtom NXUniqueString(const char *buffer);
 194     /* assumes that buffer is \0 terminated, and returns
 195      a previously created string or a new string that is a copy of buffer.
 196     If NULL is passed returns NULL.
 197     Returned string should never be modified.  To ensure this invariant,
 198     allocations are made in a special read only zone. */
 199
 200 OBJC_EXPORT NXAtom NXUniqueStringWithLength(const char *buffer, int length);
 201     /* assumes that buffer is a non NULL buffer of at least
 202     length characters.  Returns a previously created string or
 203     a new string that is a copy of buffer.
 204     If buffer contains \0, string will be truncated.
 205     As for NXUniqueString, returned string should never be modified.  */
 206
 207 OBJC_EXPORT NXAtom NXUniqueStringNoCopy(const char *string);
 208     /* If there is already a unique string equal to string, returns the original.
 209     Otherwise, string is entered in the table, without making a copy.  Argument should then never be modified.  */
 210
 211 OBJC_EXPORT char *NXCopyStringBuffer(const char *buffer);
 212     /* given a buffer, allocates a new string copy of buffer.
 213     Buffer should be \0 terminated; returned string is \0 terminated. */
 214
 215 OBJC_EXPORT char *NXCopyStringBufferFromZone(const char *buffer, void *z);
 216     /* given a buffer, allocates a new string copy of buffer.
 217     Buffer should be \0 terminated; returned string is \0 terminated. */
 218
 219 #endif
 220
 221 #endif /* _OBJC_LITTLE_HASHTABLE_H_ */