// Grid File  Interface April 6, 1995

//*********************** GridFile ******************************

class GridFile: public IndexFile has  friend GridFileScan

GridFile::GridFile (char * filename,int num_dimensions,char KeyTypes[])
    //filename is name of file
    //num_dimensions is number of index dimensions AND types in KeyTypes
    //KeyTypes is array of char where each item is the type of the
         // corresponding dimension (numbered from 0). 
         // types: i int, f float, s string  (Case insensitive)
         // If GridFile index already exists, it is opened else
         //      it is created.
         // Dimensions and key types are stored in private class
         // variables for subsequent use by all GridFile procedures.

GridFile::~GridFile ()
      //destructor closes index

Status GridFile:insert_record(RID record_id, void * KeyArray[])
   //KeyArray must have number of members equal to num_dimensions
   //    passed to constructor previously. KeyArray[0] corresponds
   //    to key given for dimension 0, keyarray[1] is key given for
   //    dimension 1 and so on. Key types are assumed to correspond
   //    to the types passed to the constructor originally in the
   //    KeyTypes array.
   //    No dimension key value should be unspecified in insert_record. 


Status GridFile:delete_record(RID record_id, void * KeyArray[])
   //KeyArray must have number of members equal to num_dimensions
   //    passed to constructor previously. KeyArray[0] corresponds
   //    to key given for dimension 0, keyarray[1] is key given for
   //    dimension 1 and so on. Key types are assumed to correspond
   //    to the types passed to the constructor originally in the
   //    KeyTypes array.
   //    No dimension key value should be unspecified in delete_record. 

//***************************** Scans ****************************

GridFile_scan: public IndexFileScan

Status GridFile_scan::GridFile_scan(GridFile * fileptr)
   //Full scan on given gridfile.


Status GridFile_scan::GridFile_scan(GridFile * fileptr,
         void *KeyArray[])
   //Create a case of an exact scan on given gridfile.
   //If a key is not being specified here then its pointer must
   // be set to null in the KeyArray. Looks for exact match on
   // keys that are specified. Key's dimension and type must 
   // match as in insert_record and delete_record.
   
Status GridFile_scan::GridFile_scan(GridFile * fileptr,;
      void *LowKeys[], void *HighKeys[])
   //Create a case of min/max scan on given gridfile.
   //If a key is not being specified here then its pointer must
   // be set to null in the KeyArray. 
   // Key's dimension and type must 
   // match as in insert_record and delete_record.
   

Status GridFile_scan:: get_next (RID & record_id)
    // Scan returns next record qualifies under ongoing scan if
    //        there is one.

Status GridFile_scan::delete_current_record()
    // Scan deletes current record