Record.h

#ifndef RECORD_H
#define RECORD_H

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string>

#include "Defs.h"
#include "ParseTree.h"
#include "Record.h"
#include "Schema.h"
#include "File.h"
#include "Comparison.h"
#include "ComparisonEngine.h"

using namespace std;

// Basic record data structure. Data is actually stored in "bits" field. The layout of bits is as follows:
//	1) First sizeof(int) bytes: length of the record in bytes
//	2) Next sizeof(int) bytes: byte offset to the start of the first att
//	3) Byte offset to the start of the att in position numAtts
//	4) Bits encoding the record's data

class Record {

    friend class ComparisonEngine;

    friend class Page;

    friend  class BigQ;

    friend class Sum;

private:
    char *GetBits();

    void SetBits(char *bits);

    void CopyBits(char *bits, int b_len);

public:
    char *bits;

    Record();

    Record(Schema *schema);

    ~Record();

    // suck the contents of the record fromMe into this; note that after
    // this call, fromMe will no longer have anything inside of it
    void Consume(Record *fromMe);

    // make a copy of the record fromMe; note that this is far more
    // expensive (requiring a bit-by-bit copy) than Consume, which is
    // only a pointer operation
    void Copy(Record *copyMe);

    // reads the next record from a pointer to a text file; also requires
    // that the schema be given; returns a 0 if there is no data left or
    // if there is an error and returns a 1 otherwise
    int SuckNextRecord(Schema *mySchema, FILE *textFile);

    // this projects away various attributes...
    // the array attsToKeep should be sorted, and lists all of the attributes
    // that should still be in the record after Project is called.  numAttsNow
    // tells how many attributes are currently in the record
    void Project(int *attsToKeep, int numAttsToKeep, int numAttsNow);

    // takes two input records and creates a new record by concatenating them;
    // this is useful for a join operation
    void MergeRecords(Record *left, Record *right, int numAttsLeft,
                      int numAttsRight, int *attsToKeep, int numAttsToKeep, int startOfRight);

    // prints the contents of the record; this requires
    // that the schema also be given so that the record can be interpreted
    void Print(Schema *mySchema);

    string ToString(Schema *mySchema);

    int NumberOfAtts();

    void ClearRecord();

    bool IsRecordEmpty();
};

#endif