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hashtable.cpp
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hashtable.cpp
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#ifndef HASHTABLE_CPP
#define HASHTABLE_CPP
#include <iostream>
#include <vector>
#include <stdint.h>
#include <string.h>
using namespace std;
typedef struct HashTableItem{
uint32_t Sum;
uint32_t Hash;
uint8_t* Key;
int KeyLen;
void* Item;
} HashTableItem;
#define MAX_SIZE_HASHTABLE 0xffffff
#define BUFF_SIZE_HASHTABLE 0xff
template<typename T>
class HashTable {
private:
vector<HashTableItem> Table;
int Size;
int nItems;
int ResizeLine;
int MaxKeyLen;
public:
HashTable(int s = 8) {
Size = (1 << s)-1;
Table.resize(Size+1, {0, 0, NULL, 0, NULL});
nItems = 0;
ResizeLine = Size >> 2;
MaxKeyLen = 0;
}
~HashTable() {
for (int i = 0; i < Table.size(); i++) {
if (Table[i].Key) {
delete Table[i].Key;
delete (T*)Table[i].Item;
}
}
}
int GetMaxKeyLen() {
return MaxKeyLen;
}
uint32_t GenHash(uint8_t* key, int len) {
uint32_t hash = 0;
for (int i = 0; i < len; i++) {
hash += (hash << 2) + key[i];
}
return hash;
}
uint32_t Sum(uint8_t* key, int len) {
uint32_t sum = 0;
for (int i = 0; i < len; i++) {
sum += key[i];
}
return sum;
}
uint32_t TraceHash(uint8_t* key, int len, uint32_t* hash, uint32_t* sum) {
hash[0] = key[0];
sum[0] = key[0];
for (int i = 1; i < len; i++) {
hash[i] = (hash[i-1] << 2) + hash[i-1] + key[i];
sum[i] = sum[i-1] + key[i];
}
return hash[len-1];
}
int Resize() {
if (Size > MAX_SIZE_HASHTABLE) {
return -1;
}
int prevsize = Size;
Size <<= 2;
Size |= 3;
ResizeLine = Size >> 2;
vector<HashTableItem> old = Table;
Table.clear();
Table.resize(Size+1, {0, 0, NULL, 0, NULL});
for (int i = 0; i < prevsize; i++) {
if (old[i].Key) {
uint32_t base = old[i].Hash & Size;
int j;
for (j = base; j < base + Size; j++) {
if (!Table[j].Key) {
Table[j] = old[i];
break;
}
}
if (j == base + Size) {
cout << "HashTable: Could not find free slot" << endl;
return -1;
}
}
}
return 0;
}
T& Get(uint8_t* key, int len) {
uint32_t s = Sum(key, len);
uint32_t h = GenHash(key, len);
if (nItems > ResizeLine) {
cout << "Hashtable: Could not expand" << endl;
if (Resize()) exit(-1);
}
for (int i = 0; i < Size; i++) {
int j = (h + i) & Size;
if (!Table[j].Key) {
Table[j].Sum = s;
Table[j].Hash = h;
Table[j].Key = new uint8_t[len];
Table[j].KeyLen = len;
for (int i = 0; i < len; i++) {
Table[j].Key[i] = key[i];
}
Table[j].Item = new T;
nItems++;
if (len > MaxKeyLen) MaxKeyLen = len;
return *(T*)Table[j].Item;
}
if (Table[j].Sum == s && Table[j].Hash == h && len == Table[j].KeyLen
&& !memcmp(key, Table[j].Key, len)) {
return *(T*)Table[j].Item;
}
}
cout << "HashTable: Could not find free slot" << endl;
exit(-1);
}
T& Get(string key) {
return Get((uint8_t*)key.c_str(), key.size());
}
T* Find(uint8_t* key, int len) {
return Find(key, len, GenHash(key, len), Sum(key, len));
}
T* Find(string key) {
return Find((uint8_t*)key.c_str(), key.size());
}
T* Find(uint8_t* key, int len, uint32_t hash, uint32_t sum) {
for (int i = 0; i < Size; i++) {
int j = (hash + i) & Size;
if (!Table[j].Key) {
return NULL;
}
if (Table[j].Sum == sum && Table[j].Hash == hash && len == Table[j].KeyLen
&& !memcmp(key, Table[j].Key, len)) {
return (T*)Table[j].Item;
}
}
return NULL;
}
T Set(string key, T& val) {
return Get(key) = val;
}
struct keyval {
string key;
T val;
};
int Set(vector<struct keyval> arg) {
for (int i = 0; i < arg.size(); i++) {
Get(arg[i].key) = arg[i].val;
}
return arg.size();
}
int SearchBack(uint8_t* key, int len = 0, T** buff = NULL) {
uint32_t buff_hash[BUFF_SIZE_HASHTABLE], buff_sum[BUFF_SIZE_HASHTABLE];
if (len <= 0 || len > MaxKeyLen) len = MaxKeyLen;
uint32_t* hash;
uint32_t* sum;
if (len > BUFF_SIZE_HASHTABLE) {
hash = new uint32_t[len];
sum = new uint32_t[len];
} else {
hash = buff_hash;
sum = buff_sum;
}
TraceHash(key, len, hash, sum);
int ret = 0;
if (buff) {
for (int i = 0; i < len; i++) {
if (buff[i] = Find(key, i+1, hash[i], sum[i])) {
ret = i + 1;
}
}
} else {
for (int i = len; i; i--) {
if (Find(key, i, hash[i-1], sum[i-1])){
ret = i;
break;
}
}
}
if (hash != buff_hash) {
delete hash;
delete sum;
}
return ret;
}
int SearchBack(string key, T** buff = NULL) {
return SearchBack((uint8_t*)key.c_str(), key.size(), buff);
}
};
#endif