print.c

linux 下用c++ 开发的一个小型数据库系统

#include <stdio.h>
#include "catalog.h"
#include "utility.h"


#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))


//
// Compute widths of columns in attribute array.
//

const Status UT_computeWidth(const int attrCnt, 
			     const AttrDesc attrs[], 
			     int *&attrWidth)
{
  attrWidth = new int [attrCnt];
  if (!attrWidth)
    return INSUFMEM;

  for(int i = 0; i < attrCnt; i++) {
    int namelen = strlen(attrs[i].attrName);
    switch(attrs[i].attrType) {
    case INTEGER:
    case FLOAT:
      attrWidth[i] = MIN(MAX(namelen, 5), 7);
      break;
    case STRING:
      attrWidth[i] = MIN(MAX(namelen, attrs[i].attrLen), 20);
      break;
    }
  }

  return OK;
}


//
// Prints values of attributes stored in buffer pointed to
// by recPtr. The desired width of columns is in attrWidth.
//

void UT_printRec(const int attrCnt, const AttrDesc attrs[], int *attrWidth,
		 const Record & rec)
{
  for(int i = 0; i < attrCnt; i++) {
    char *attr = (char *)rec.data + attrs[i].attrOffset;
    switch(attrs[i].attrType) {
    case INTEGER:
      int tempi;
      memcpy(&tempi, attr, sizeof(int));
      printf("%-*d  ", attrWidth[i], tempi);
      break;
    case FLOAT:
      float tempf;
      memcpy(&tempf, attr, sizeof(float));
      printf("%-*.2f  ", attrWidth[i], tempf);
      break;
    default:
      printf("%-*.*s  ", attrWidth[i], attrWidth[i], attr);
      break;
    }
  }

  printf("\n");
}


//
// Prints the contents of the specified relation.
//
// Returns:
// 	OK on success
// 	an error code otherwise
//

const Status UT_Print(string relation)
{
  Status status;
  RelDesc rd;
  AttrDesc *attrs;
  AttrDesc ads ;
  int attrCnt;
  Record rec ;
  RID rid ;
  HeapFileScan *hfs ;  
  int *attrWidth ;
  string myrel1 ;

  if (relation.empty()) relation = RELCATNAME ;
  
  if ((status = relCat->getInfo( relation, rd)) != OK) return status ;
  
  myrel1.append(rd.relName) ;  
  hfs = new HeapFileScan( myrel1, status) ;
  if (status != OK) return status ;

  if ((status = attrCat->getRelInfo( myrel1, attrCnt, attrs)) != OK){
    delete hfs ;
    return status ;
  }
  
  if ((status = UT_computeWidth( attrCnt, attrs, attrWidth)) != OK){
    delete hfs ;
    delete [] attrWidth ;
    return status ;
  }

  int recNum = 0 ;
  cout<<"\n" ;
  for(int w = 0; w < attrCnt; w++)
    printf("%-*s  ", attrWidth[w], attrs[w].attrName) ;
  
  cout<<"\n" ;
  for(int p = 0; p < attrCnt; p++){
   for (int j = 0; j < attrWidth[p]; j++)
      cout<<"-" ;
   cout<<"  " ;
  }
  cout<<"\n" ;

  hfs->startScan( 0, 0, STRING, NULL, EQ ) ;
  
  while(hfs->scanNext(rid) != FILEEOF){
     hfs->getRecord(rec) ;
     UT_printRec( attrCnt, attrs, attrWidth, rec) ;
     recNum++ ;
  }
  
  cout<<"\n   "<<recNum<<"  record (s) selected!\n" ;

  delete [] attrs ;
  delete hfs ;
  delete [] attrWidth ;
  return OK ;

}