Files
BH-Bookstore-2023/backend/include/key2index.hpp

126 lines
3.6 KiB
C++

#ifndef BPT_KEY2INDEX_HPP
#define BPT_KEY2INDEX_HPP
#include <cassert>
#include <functional>
#include <string>
#include <vector>
#include "drivearray.hpp"
class String2Index {
private:
static const int kBucketSize = 262142;
static const int kPageSize = 4096;
constexpr static char salt1[10] = "mL;]-=eT";
constexpr static char salt2[10] = "9B<mF_me";
constexpr static char sub_salt1[10] = "23333";
constexpr static char sub_salt2[10] = "...";
static inline size_t Hash(std::string str) noexcept {
str = salt1 + str + salt2;
size_t ret = 0;
for (int i = 0; i < str.length(); ++i) ret = ret * 131 + str[i];
return ret;
}
struct Node {
size_t main_hash, sub_hash;
int val, nxt_idx = 0;
Node() = default;
Node(std::string str, int _val)
: main_hash(Hash(str)),
sub_hash(Hash(sub_salt1 + str + sub_salt2)),
val(_val) {}
};
DriveArray<Node, kBucketSize, 100> mem;
int *hash_table = nullptr;
std::string file_name;
public:
String2Index() = default;
void OpenFile(const std::string __file_name) noexcept {
file_name = __file_name;
if (file_name == "") return;
if (mem.IsOpen())
for (int i = 0; i < kBucketSize; ++i)
mem.write_info(hash_table[i], i + 1);
mem.OpenFile(file_name);
delete[] hash_table;
hash_table = new int[kBucketSize];
// std::memmove(hash_table, mem.RawData(), sizeof(int) * kBucketSize);
// mem.ForceRefresh();
mem.LoadInfoTo(hash_table);
}
String2Index(const std::string __file_name) : file_name(__file_name) {
OpenFile(file_name);
}
void initialise(std::string FN = "") noexcept {
if (FN != "") file_name = FN;
if (mem.IsOpen())
for (int i = 0; i < kBucketSize; ++i)
mem.write_info(hash_table[i], i + 1);
delete[] hash_table;
mem.initialise(file_name);
hash_table = new int[kBucketSize]();
}
~String2Index() {
if (hash_table != nullptr) {
mem.WriteInfoFrom(hash_table);
delete[] hash_table;
}
}
void Insert(const std::string &str, int val) noexcept {
size_t hash_val = Hash(str);
int idx = hash_table[hash_val % kBucketSize];
Node nd(str, val);
if (idx == 0) {
idx = mem.write(nd);
hash_table[hash_val % kBucketSize] = idx;
} else {
nd.nxt_idx = idx;
idx = mem.write(nd);
hash_table[hash_val % kBucketSize] = idx;
}
}
void Delete(const std::string &str, int val) noexcept {
size_t str_main_hash = Hash(str),
str_sub_hash = Hash(sub_salt1 + str + sub_salt2);
int idx = hash_table[str_main_hash % kBucketSize];
Node nd, last_nd;
int last_idx = -1;
while (idx != 0) {
mem.read(nd, idx);
if (nd.main_hash == str_main_hash && nd.sub_hash == str_sub_hash &&
nd.val == val) {
if (last_idx == -1) {
hash_table[str_main_hash % kBucketSize] = nd.nxt_idx;
mem.Delete(idx);
} else {
last_nd.nxt_idx = nd.nxt_idx;
mem.update(last_nd, last_idx);
mem.Delete(idx);
}
return;
}
last_idx = idx;
last_nd = nd;
idx = nd.nxt_idx;
}
}
std::vector<int> Find(const std::string &str) noexcept {
std::vector<int> ret;
size_t str_main_hash = Hash(str),
str_sub_hash = Hash(sub_salt1 + str + sub_salt2);
int idx = hash_table[str_main_hash % kBucketSize];
Node nd;
while (idx != 0) {
mem.read(nd, idx);
if (nd.main_hash == str_main_hash && nd.sub_hash == str_sub_hash) {
ret.push_back(nd.val);
}
idx = nd.nxt_idx;
}
return std::move(ret);
}
};
#endif // BPT_KEY2INDEX_HPP