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secondo/Algebras/ExtRelation-2/AttributeFile.h
2026-01-23 17:03:45 +08:00

160 lines
3.1 KiB
C++

/*
----
This file is part of SECONDO.
Copyright (C) 2016, University in Hagen, Faculty of Mathematics and
Computer Science, Database Systems for New Applications.
SECONDO is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
SECONDO is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with SECONDO; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
----
*/
#ifndef ATTRIBUTEFILE_H
#define ATTRIBUTEFILE_H
#include <string>
#include "NestedList.h"
#include "Attribute.h"
/*
1 AttributeIterator
This iterator class can be used for iterating over files
constructed by the AttributeFile class.
*/
class AttributeIterator{
public:
AttributeIterator(const std::string& _filename);
AttributeIterator(const std::string& _filename,
const uint32_t _algId,
const uint32_t _typeId,
const ListExpr _typeList);
~AttributeIterator(){
if(in){
delete in;
}
if(buffer){
delete[] buffer;
}
}
inline Attribute* next(){
return in?retrieveNext():0;
}
std::streampos getPos(){
if(!in){
return -1;
}
return in->tellg();
}
private:
std::string fileName;
uint32_t algId;
uint32_t typeId;
ListExpr typeList;
std::ifstream* in;
Attribute* retrieveNext();
char* buffer;
};
/*
2 AttributeFile
This class can be used to store attributes of the same type within a file.
*/
class AttributeFile{
public:
AttributeFile(const std::string& _filename,
const uint32_t _algId,
const uint32_t _typeId,
const ListExpr _typeList,
const ListExpr _numTypeList,
const bool temp);
~AttributeFile();
bool append(Attribute* attr, bool withFlobs);
AttributeIterator* makeScan( bool close=true){
if(close && out ){
out->flush();
out->close();
if(buffer){
delete[] buffer;
buffer = 0;
}
delete out;
out = 0;
}
return new AttributeIterator(filename, algId, typeId, nType);
}
void close(){
if(out){
out->flush();
out->close();
if(buffer){
delete[] buffer;
buffer = 0;
}
delete out;
out = 0;
}
}
std::streampos getPos(){
if(!out){
return -1;
}
return out->tellp();
}
private:
std::string filename;
uint32_t algId;
uint32_t typeId;
ListExpr typeList;
ListExpr nType;
bool temp;
std::ofstream* out;
char* buffer;
};
#endif