cbLRUCache.hpp

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#include <map>
#include <list>
#include "../../pch.hpp"
 
#define find_list for (auto i = m_cacheList.begin(); i != m_cacheList.end(); i++)
 
namespace cb {
struct listNode {
  std::string key;
};
 
typedef listNode node;
 
template<typename V>
class cbLRUCache {
 public:
  cbLRUCache(int32_t max_size) : m_maxSize(max_size), m_sizeCounter(0), m_bufNode(nullptr) {}
 
  ~cbLRUCache() { delete m_bufNode; }
 
  void push(std::string key, V value) {
    find_list {
      if (i->key == key) {
        m_cacheMap[key] = value;
        this->update(key);
        return;
      }
    }
 
    m_sizeCounter++;
    if (m_sizeCounter > m_maxSize) {
      m_sizeCounter = m_maxSize;
      this->eraseTail();
    }
    m_cacheMap.insert({key, value});
    this->insertTop(key);
  }
 
  V* get(const std::string& key) {
    if (m_cacheMap.count(key)) {
      this->update(key);
      V* exit = nullptr;
      exit = &m_cacheMap[key];
      // this->__loop_map();
      return exit;
    }
    V* not_exit = nullptr;
    return not_exit;
  }
 
 private:
  void eraseTail() {
    m_bufNode = &m_cacheList.back();
    m_bufKey = m_bufNode->key;
    auto buf_ptr = m_cacheMap.find(m_bufKey);
    m_cacheMap.erase(buf_ptr);
    m_cacheList.pop_back();
  }
 
  void update(const std::string& key) {
    find_list {
      if (i->key == key) {
        m_cacheList.erase(i);
        break;
      }
    }
    this->insertTop(key);
  }
 
  void insertTop(const std::string& key) {
    m_bufNode = new (node);
    m_bufNode->key = key;
    m_cacheList.push_front(*m_bufNode);
    delete (m_bufNode);
    m_bufNode = nullptr;
  }
 
  [[deprecated("For debug only")]] void __loop_map() {
    std::string bs;
    int32_t n = 0;
    for (auto i = m_cacheList.begin(); i != m_cacheList.end(); i++) {
      bs = i->key;
      std::cout << "The" << n << "th element" << bs << " : " << m_cacheMap[bs] << std::endl;
      n++;
    }
  }
 
 private:
  int32_t m_maxSize;
  int32_t m_sizeCounter;
  node* m_bufNode;
  std::string m_bufKey;
  std::list<node> m_cacheList;
  std::map<std::string, V> m_cacheMap;
};
}  // namespace cb