catalog.c

linux 下用c++ 开发的一个小型数据库系统

#include "catalog.h"


RelCatalog::RelCatalog(Status &status) :
	 HeapFile(RELCATNAME, status)
{
// nothing needed
}


const Status RelCatalog::getInfo(const string & relation, RelDesc &record)
{
  if (relation.empty())
    return BADCATPARM;

  Status status;
  Record rec;
  RID rid;
  HeapFileScan *ifs ;
  
  ifs = new HeapFileScan( RELCATNAME, status) ; 
  if (status != OK) return status ;

  ifs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  
  if(ifs->scanNext(rid) == OK){
    if ((status = getRecord( rid, rec)) != OK){
      delete ifs ;
      return status ;
    }
    memcpy( &record, rec.data, rec.length) ;

    delete ifs ;
    return OK ;
  }  
  delete ifs ;
  return RELNOTFOUND ;
}


const Status RelCatalog::addInfo(RelDesc & record)
{
  RID rid;
  InsertFileScan*  ifs;
  Status status;
  Record rec ;
  string myrelName ;
  RelDesc myrec ;

  ifs = new InsertFileScan( RELCATNAME, status) ;
  if (status != OK) return status ;
  
  myrelName.append(record.relName) ;  
  if ((status = getInfo( myrelName, myrec )) == OK){
    delete ifs ;
    return RELEXISTS ;
  }



  rec.data = &record ;
  rec.length = sizeof(RelDesc) ;
  if ((status = ifs->insertRecord( rec, rid)) != OK){
    delete ifs ;
    return status ;
  }
  delete ifs ;
  
  return OK ;
}

const Status RelCatalog::removeInfo(const string & relation)
{
  Status status;
  RID rid;
  HeapFileScan*  hfs;

  if (relation.empty()) return BADCATPARM;

  hfs = new HeapFileScan( RELCATNAME, status) ;
  if (status != OK) return status ;

  hfs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  
  if((status = hfs->scanNext(rid)) == OK){  
    if ((status = hfs->deleteRecord()) != OK){
      delete hfs ;
      return status ;
    }
    delete hfs ;
    return OK ;
  }
  delete hfs ;
  return RELNOTFOUND ;
}


RelCatalog::~RelCatalog()
{
// nothing needed
}


AttrCatalog::AttrCatalog(Status &status) :
	 HeapFile(ATTRCATNAME, status)
{
// nothing needed
}


const Status AttrCatalog::getInfo(const string & relation, 
				  const string & attrName,
				  AttrDesc &record)
{

  Status status;
  RID rid;
  Record rec;
  HeapFileScan*  hfs;
   
  hfs = new HeapFileScan( ATTRCATNAME, status) ;
  if (status != OK) return status ;

  hfs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  
  while ((status = hfs->scanNext(rid)) != FILEEOF){
    if ((status = hfs->getRecord(rec)) != OK){
      delete hfs ; 
      return status ;
    }
    memcpy( &record, rec.data, rec.length) ;

    if (strncmp ( record.attrName,attrName.c_str(), attrName.length()) == 0){
      delete hfs ;
      return OK ;
    } 
  }
  delete hfs ;
  return ATTRNOTFOUND ;
}


const Status AttrCatalog::addInfo(AttrDesc & record)
{
  RID rid;
  InsertFileScan*  ifs;
  Status status;
  Record rec ;
  string myattr, myrel ;
  AttrDesc myads ;

  ifs = new InsertFileScan( ATTRCATNAME, status) ;
  if (status != OK) return status ;
  
  myrel.append(record.relName) ;
  myattr.append(record.attrName) ;
  if ((status = getInfo( myrel, myattr, myads)) == OK){
    delete ifs ;
    return DUPLATTR ;
  }
  rec.data = &record ;



  rec.length = sizeof(AttrDesc) ;  
  if ((status = ifs->insertRecord( rec, rid)) != OK){
    delete ifs ;
    return status ;
  }
  
  delete ifs ;
  return OK ;
}


const Status AttrCatalog::removeInfo(const string & relation, 
			       const string & attrName)
{
  Status status;
  Record rec;
  RID rid;
  AttrDesc record;
  RelDesc relrec ;
  HeapFileScan*  hfs;

  if (relation.empty() || attrName.empty()) return BADCATPARM;
  
  hfs = new HeapFileScan ( ATTRCATNAME, status) ;
  if (status != OK) return status ;

  if((status = relCat->getInfo( relation, relrec)) != OK){
    delete hfs ;
    return status ;
  }

  hfs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  
  while((status = hfs->scanNext(rid)) != FILEEOF){
    if ((status = hfs->getRecord(rec)) != OK){
      delete hfs ;
      return status ;
    }
    memcpy( &record, rec.data, rec.length) ; 
    if (strncmp(record.attrName, attrName.c_str(), attrName.length()) == 0){
      hfs->deleteRecord() ;
      delete hfs ;
      return OK ;
    }
  }

  delete hfs ;
  return ATTRNOTFOUND ;
}


const Status AttrCatalog::getRelInfo(const string & relation, 
				     int &attrCnt,
				     AttrDesc *&attrs)
{
  Status status;
  RID rid;
  Record rec;
  HeapFileScan*  hfs;
  int i ;

  if (relation.empty()) return BADCATPARM;

  hfs = new HeapFileScan( ATTRCATNAME, status) ;
  if (status != OK) return status ;
  
  i = 0 ;
  hfs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  while((status = hfs->scanNext(rid)) != FILEEOF){
    i++ ;
  }
  
  attrs = new AttrDesc[i] ;
  hfs = new HeapFileScan( ATTRCATNAME, status) ;
  if (status != OK) return status ;
  
  hfs->startScan( 0, relation.length(), STRING, relation.c_str(), EQ) ;
  i = 0 ;
  while(hfs->scanNext(rid) != FILEEOF){   
     hfs->getRecord(rec) ;
     memcpy( &attrs[i], rec.data, rec.length) ; 
     i++ ; 
  } 
  attrCnt = i ;
  delete hfs ;
  return OK ;
}


AttrCatalog::~AttrCatalog()
{
// nothing needed
}