php扩展开发-实现一个简易的哈希表
从一个简易的哈希表入手，会让你更好的理解php的哈希表，他们的本质是一样的，只是php的哈希表做了更多的功能扩展，php的哈希表是php语言的一个重要核心，大量的内核代码使用到哈希表。
1 #include <string.h> 2 #include <stdio.h> 3 #include <stdlib.h> 4 #define HASH_ADD 0 5 #define HASH_UPDATE 1 6 7 typedef unsigned long ulong; 8 typedef unsigned int uint; 9 10 typedef struct bucket { 11 ulong h; //字符数组的key哈希值或者数字数组的key值 12 uint nKeyLength;//字符数组的key长度，数字数组为0 13 void *pData;//存储的数据 14 struct bucket *pListNext;//在哈希表中的下一个元素 15 struct bucket *pListLast;//在哈希表中的下一个元素 16 struct bucket *pNext;//哈希值冲突时，同一哈希值链表的下一个元素 17 struct bucket *pLast;//哈希值冲突时，同一哈希值链表的上一个元素 18 const char *arKey;//字符数组的key值，数字数组为NULL 19 } Bucket; 20 21 typedef struct _hashtable { 22 uint nTableSize;//哈希表的大小 23 uint nTableMask;//用来计算哈希值所在当前哈希表的位置 24 uint nNumOfElements;//哈希表的元素数量 25 ulong nNextFreeElement;//下一个自动插入的位置 26 Bucket *pListHead;//哈希表的第一个元素 27 Bucket *pListTail;//哈希表的最后一个元素 28 Bucket **arBuckets;//哈希表存储数据的数组 29 } HashTable; 30 31 int hash_init(HashTable *ht, uint nSize); 32 int hash_add(HashTable *ht, const char *arKey, uint nKeyLength, void *pData); 33 int hash_update(HashTable *ht, const char *arKey, uint nKeyLength, void *pData); 34 int _hash_add_update(HashTable *ht, const char *arKey, uint nKeyLength, void *pData, int flag); 35 int hash_index_add(HashTable *ht, ulong h, void *pData); 36 int hash_index_update(HashTable *ht, ulong h, void *pData); 37 int hash_foreach(HashTable *ht); 38 static int hash_resize_if_full(HashTable *ht); 39 int hash_resize(HashTable *ht); 40 char * hash_find(HashTable *ht,const char *arKey); 41 char * hash_index_find(HashTable *ht,ulong h); 42 43 int hash_init(HashTable *ht, uint nSize){ 44 uint i = 1; 45 46 if (nSize >= 0x80000000) { 47 /* prevent overflow */ 48 ht->nTableSize = 0x80000000; 49 } else { 50 while ((1U << i) < nSize) { 51 i++; 52 } 53 ht->nTableSize = 1 << i; 54 } 55 ht->nTableMask = ht->nTableSize - 1; 56 ht->nNumOfElements = 0; 57 ht->nNextFreeElement = 0; 58 ht->pListHead = NULL; 59 ht->pListTail = NULL; 60 ht->arBuckets = (Bucket **)calloc(ht->nTableSize,sizeof(Bucket *)); 61 return 0; 62 } 63 64 static inline ulong hash_func(const char *arKey, uint nKeyLength) 65 { 66 register ulong hash = 5381; 67 68 /* variant with the hash unrolled eight times */ 69 for (; nKeyLength >= 8; nKeyLength -= 8) { 70 hash = ((hash << 5) + hash) + *arKey++; 71 hash = ((hash << 5) + hash) + *arKey++; 72 hash = ((hash << 5) + hash) + *arKey++; 73 hash = ((hash << 5) + hash) + *arKey++; 74 hash = ((hash << 5) + hash) + *arKey++; 75 hash = ((hash << 5) + hash) + *arKey++; 76 hash = ((hash << 5) + hash) + *arKey++; 77 hash = ((hash << 5) + hash) + *arKey++; 78 } 79 switch (nKeyLength) { 80 case 7: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 81 case 6: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 82 case 5: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 83 case 4: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 84 case 3: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 85 case 2: hash = ((hash << 5) + hash) + *arKey++; /* fallthrough... */ 86 case 1: hash = ((hash << 5) + hash) + *arKey++; break; 87 case 0: break; 88 } 89 return hash; 90 } 91 92 int hash_add(HashTable *ht, const char *arKey, uint nKeyLength, void *pData){ 93 return _hash_add_update(ht, arKey, nKeyLength, pData, HASH_ADD); 94 } 95 96 int hash_update(HashTable *ht, const char *arKey, uint nKeyLength, void *pData){ 97 return _hash_add_update(ht, arKey, nKeyLength, pData, HASH_UPDATE); 98 } 99 100 int _hash_add_update(HashTable *ht, const char *arKey, uint nKeyLength, void *pData, int flag){ 101 Bucket *p; 102 ulong h; 103 ulong nIndex; 104 h = hash_func(arKey, nKeyLength); 105 nIndex = h & ht->nTableMask; 106 p = ht->arBuckets[nIndex]; 107 while (p != NULL) { 108 //printf("nIndex=>%d,arKey=>%s,p=>%s,%s\n",nIndex,arKey,p->arKey,p->pData); 109 if (p->arKey == arKey){ 110 if(flag == HASH_ADD){ 111 //已经存在同样的key 112 return -1; 113 }else{ 114 p->pData = pData; 115 return 0; 116 } 117 } 118 p = p->pNext; 119 } 120 p = (Bucket *)malloc(sizeof(Bucket)); 121 p->h = h; 122 p->nKeyLength = nKeyLength; 123 p->pData = pData; 124 p->pNext = ht->arBuckets[nIndex]; 125 p->pLast = NULL; 126 if(p->pNext != NULL){ 127 p->pNext->pLast = p; 128 } 129 p->arKey = arKey; 130 ht->arBuckets[nIndex] = p; 131 ht->nNumOfElements++; 132 if(ht->pListHead == NULL){ 133 ht->pListHead = p; 134 p->pListNext = NULL; 135 p->pListLast = NULL; 136 ht->pListTail = p; 137 }else{ 138 p->pListLast = ht->pListTail; 139 p->pListLast->pListNext = p; 140 p->pListNext = NULL; 141 ht->pListTail = p; 142 } 143 hash_resize_if_full(ht); 144 return 0; 145 } 146 147 int hash_index_add(HashTable *ht, ulong h, void *pData){ 148 return _hash_index_add_update(ht,h,pData,HASH_ADD); 149 } 150 151 int hash_index_update(HashTable *ht, ulong h, void *pData){ 152 return _hash_index_add_update(ht,h,pData,HASH_UPDATE); 153 } 154 155 int hash_next_add(HashTable *ht,void *pData){ 156 ulong h = ht->nNextFreeElement; 157 return _hash_index_add_update(ht,h,pData,HASH_ADD); 158 } 159 160 int _hash_index_add_update(HashTable *ht, ulong h,void *pData,int flag){ 161 Bucket *p; 162 ulong nIndex; 163 nIndex = h & ht->nTableMask; 164 p = ht->arBuckets[nIndex]; 165 while (p != NULL) { 166 if (p->arKey == NULL && p->nKeyLength == 0){ 167 if(flag == HASH_ADD){ 168 //已经存在同样的key 169 return -1; 170 }else{ 171 p->pData = pData; 172 return 0; 173 } 174 } 175 p = p->pNext; 176 } 177 p = (Bucket *)malloc(sizeof(Bucket)); 178 p->h = h; 179 p->nKeyLength = 0; 180 p->pData = pData; 181 p->pNext = ht->arBuckets[nIndex]; 182 p->pLast = NULL; 183 if(p->pNext != NULL){ 184 p->pNext->pLast = p; 185 } 186 p->arKey = NULL; 187 ht->arBuckets[nIndex] = p; 188 ht->nNumOfElements++; 189 if(h >= ht->nNextFreeElement){ 190 ht->nNextFreeElement = h + 1; 191 } 192 if(ht->pListHead == NULL){ 193 ht->pListHead = p; 194 p->pListNext = NULL; 195 p->pListLast = NULL; 196 ht->pListTail = p; 197 }else{ 198 p->pListLast = ht->pListTail; 199 p->pListLast->pListNext = p; 200 p->pListNext = NULL; 201 ht->pListTail = p; 202 } 203 hash_resize_if_full(ht); 204 return 0; 205 } 206 207 int hash_foreach(HashTable *ht){ 208 if(ht->pListHead == NULL){ 209 return ; 210 } 211 Bucket *p; 212 p = ht->pListHead; 213 while(p != NULL){ 214 if(p->nKeyLength > 0){ 215 printf("h=>%ld,index=>%ld,%s=>%s\n",p->h,p->h & ht->nTableMask,p->arKey,p->pData); 216 }else{ 217 printf("h=>%ld,index=>%ld,%d=>%s\n",p->h,p->h & ht->nTableMask,p->h,p->pData); 218 } 219 p=p->pListNext; 220 } 221 } 222 223 static int hash_resize_if_full(HashTable *ht){ 224 //printf("if_null,num=>%d,size=>%d\n",ht->nNumOfElements,ht->nTableSize); 225 if(ht->nNumOfElements >= ht->nTableSize){ 226 return hash_resize(ht); 227 } 228 } 229 230 int hash_resize(HashTable *ht){ 231 printf("before resize:%d\n",ht->nTableSize); 232 hash_foreach(ht); 233 ht->nTableSize = ht->nTableSize << 1; 234 ht->nTableMask = ht->nTableSize - 1; 235 Bucket **t; 236 t = realloc(ht->arBuckets,ht->nTableSize * sizeof(Bucket*)); 237 memset(t,0,ht->nTableSize * sizeof(Bucket *)); 238 ht->arBuckets = t; 239 Bucket *p; 240 ulong nIndex; 241 for(p=ht->pListHead;p!=NULL;p=p->pListNext){ 242 nIndex = p->h & ht->nTableMask; 243 p->pNext = ht->arBuckets[nIndex]; 244 if(p->pNext != NULL){ 245 p->pNext->pLast = p; 246 } 247 ht->arBuckets[nIndex] = p; 248 } 249 printf("after resize:%d\n",ht->nTableSize); 250 hash_foreach(ht); 251 return 0; 252 } 253 254 char * hash_find(HashTable *ht,const char *arKey){ 255 ulong h; 256 int nKeyLength = strlen(arKey); 257 h = hash_func(arKey, nKeyLength); 258 ulong nIndex = h & ht->nTableMask; 259 Bucket *p; 260 for(p=ht->arBuckets[nIndex];p!=NULL;p=p->pNext){ 261 if(strcmp(p->arKey,arKey) == 0 && p->nKeyLength == nKeyLength){ 262 return p->pData; 263 } 264 printf("hash_find,arKey=>%s,nKeyLength=>%d,pData=>%s\n",p->arKey,p->nKeyLength,p->pData); 265 } 266 return NULL; 267 } 268 269 char * hash_index_find(HashTable *ht,ulong h){ 270 ulong nIndex = h & ht->nTableMask; 271 Bucket *p; 272 for(p=ht->arBuckets[nIndex];p!=NULL;p=p->pNext){ 273 if(p->nKeyLength == 0 && p->arKey == NULL){ 274 return p->pData; 275 } 276 } 277 } 278 279 int main(){ 280 HashTable *ht; 281 ht = (HashTable *)malloc(sizeof(HashTable)); 282 hash_init(ht,1);//初始化哈希表，nTableSize=1 283 char *arKey = "keya"; 284 int len = strlen(arKey); 285 char *pData = "valuea"; 286 hash_add(ht,arKey,len,pData);//插入字符串数据 287 arKey = "keyb"; 288 len = strlen(arKey); 289 pData = "valueb"; 290 hash_add(ht,arKey,len,pData); 291 arKey = "keyb"; 292 len = strlen(arKey); 293 pData = "valueb"; 294 int ret = hash_add(ht,arKey,len,pData);//插入失败，key已经存在 295 printf("ret=>%d\n",ret); 296 char c; 297 //char buffer[100]; 298 char *buffer; 299 for(c='c';c<='z';c++){ 300 buffer = (char *)malloc(100); 301 sprintf(buffer,"key%c",c); 302 arKey = buffer; 303 len = strlen(arKey); 304 buffer = (char *)malloc(100); 305 sprintf(buffer,"value%c",c); 306 pData = buffer; 307 printf("%s,%s\n",arKey,pData); 308 hash_add(ht,arKey,len,pData);//批量插入 309 } 310 for(c='A';c<='Z';c++){ 311 buffer = (char *)malloc(100); 312 sprintf(buffer,"value%c",c); 313 pData = buffer; 314 hash_next_add(ht,pData);//使用数字数组，自动插入元素，不需要指定key 315 } 316 hash_index_add(ht,100,"index3");//使用数字数组，指定索引位置。 317 hash_next_add(ht,"101"); 318 hash_next_add(ht,"102"); 319 hash_index_update(ht,100,"100 -> 102");//更新指定位置的值 320 hash_foreach(ht);//遍历数组 321 char *finda = hash_find(ht,"keya");//查找指定字符串key的值 322 printf("finda=>%s\n",finda); 323 char *findb = hash_index_find(ht,100);//查找指定索引的值 324 printf("findb=>%s\n",findb); 325 }
