//
//?Created?by?apple?on?2017/7/21.
//

#include?“database.h“

Database::Database（const?std::string?&db_name）
{
????if?（db_name?!=?““）?{?open（db_name）;?}
}

Database::~Database（void）
{
????close（）;
}

inline?Offset?Database::_hash（const?std::string?&key）
{
????uint32_t?seed?=?13;?//?31?131?1313?13131?131313?etc..
????uint32_t?hash_val?=?0;
????uint32_t?mask?=?hash_table_size?-?1;
????
????for?（char?ch?:?key）?{?hash_val?=?hash_val?*?seed?+?ch;?}
????
????return?hash_val?%?mask;
}

void?Database::open（const?std::string?&db_name）
{
????close（）;
????_index_file.open（db_name?+?index_file_suffix?std::ios::binary?|?std::ios::in?|?std::ios::out）;
????_data_file.open（db_name?+?data_file_suffix?std::ios::binary?|?std::ios::in?|?std::ios::out）;
}

void?Database::close（void）
{
????_index_file.close（）;
????_data_file.close（）;
}

void?Database::insert（const?std::string?&key?const?std::string?&data）
{
????if?（!_index_file.is_open（）?||?!_data_file.is_open（））?{?return;?}
????
????Offset?hash_offset?=?_hash（key）?*?sizeof（HashItem）;
????HashItem?hash_item?=?_read_hash_item（hash_offset）;
????
????if?（_get_index_offset（hash_item?key）?!=?-1）?{?return;?}
????
????_data_file.seekp（0?std::ios::end）;
????
????HashItem?hash_head?=?_read_hash_item（0）;
????IndexInfo?index_info?=?{?.next?=?hash_item.first?.key_len?=?（Size）（key.size（）?+?1）?};
????Offset?index_offset?=?hash_head.first;
????Offset?data_offset?=?_data_file.tellp（）;
????DataInfo?data_info?=?{?.data_len?=?（Size）（data.length（）?+?1）?.deleted?=?0?};
????
????_write_index_info（index_offset?index_info）;
????_write_data_offset（index_offset?data_offset）;
????_write_key（index_offset?key）;
????_write_data_info（data_offset?data_info）;
????_write_data（data_offset?data）;
????
????hash_head.first?=?_index_file.tellp（）;
????_write_hash_item（0?hash_head）;
????
????hash_item.count++;
????hash_item.first?=?index_offset;
????_write_hash_item（hash_offset?hash_item）;
}

void?Database::remove（const?std::string?&key）
{
????if?（!_index_file.is_open（）?||?!_data_file.is_open（））?{?return;?}
????
????Offset?hash_offset?=?_hash（key）?*?sizeof（HashItem）;
????HashItem?hash_item?=?_read_hash_item（hash_offset）;
????if?（hash_item.count?==?0）?{?return;?}
????
????IndexInfo?index_info;
????Offset?prev_index_offset?=?-1;
????Offset?curr_index_offset?=?hash_item.first;
????
????bool?found?=?false;
????
????for?（int?i?=?0;?i?????{
????????index_info?=?_read_index_info（curr_index_offset）;
????????std::string?index_key?=?_read_key（curr_index_offset?index_info.key_len）;
????????
????????if?（index_key?==?key）
????????{
????????????found?=?true;
????????????break;
????????}
????????
????????prev_index_offset?=?curr_index_offset;
????????curr_index_offset?=?index_info.next;
????}
????
????if?（found）
????{
????????Offset?data_offset?=?_read_data_offset（curr_index_offset）;
????????DataInfo?data_info?=?_read_data_info（data_offset）;
????????
????????data_info.deleted?=?1;
????????_write_data_info（data_offset?data_info）;
??

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2017-07-23?21:08??Database-master\
?????文件?????????232??2017-07-23?21:08??Database-master\CMakeLists.txt
?????目錄???????????0??2018-02-28?11:58??__MACOSX\
?????目錄???????????0??2018-02-28?11:58??__MACOSX\Database-master\
?????文件?????????216??2017-07-23?21:08??__MACOSX\Database-master\._CMakeLists.txt
?????文件????????9870??2017-07-23?21:08??Database-master\database.cpp
?????文件?????????216??2017-07-23?21:08??__MACOSX\Database-master\._database.cpp
?????文件????????2467??2017-07-23?21:08??Database-master\database.h
?????文件?????????216??2017-07-23?21:08??__MACOSX\Database-master\._database.h
?????文件????????2020??2017-07-23?21:08??Database-master\main.cpp
?????文件?????????216??2017-07-23?21:08??__MACOSX\Database-master\._main.cpp
?????文件??????????49??2017-07-23?21:08??Database-master\README.md
?????文件?????????216??2017-07-23?21:08??__MACOSX\Database-master\._README.md
?????文件?????????216??2017-07-23?21:08??__MACOSX\._Database-master