/**
* constructor
*
* @param file_name heapfile to be opened
* @param in1[] array showing what the attributes of the input fields are.
* @param s1_sizes[] shows the length of the string fields.
* @param len_in1 number of attributes in the input tuple
* @param n_out_flds number of fields in the out tuple
* @param proj_list shows what input fields go where in the output tuple
* @param outFilter select expressions
* @exception IOException some I/O fault
* @exception FileScanException exception from this class
* @exception TupleUtilsException exception from this class
* @exception InvalidRelation invalid relation
*/
public FileScan(
String file_name,
AttrType in1[],
short s1_sizes[],
short len_in1,
int n_out_flds,
FldSpec[] proj_list,
CondExpr[] outFilter)
throws IOException, FileScanException, TupleUtilsException, InvalidRelation {
_in1 = in1;
in1_len = len_in1;
s_sizes = s1_sizes;
Jtuple = new Tuple();
AttrType[] Jtypes = new AttrType[n_out_flds];
short[] ts_size;
ts_size =
TupleUtils.setup_op_tuple(Jtuple, Jtypes, in1, len_in1, s1_sizes, proj_list, n_out_flds);
OutputFilter = outFilter;
perm_mat = proj_list;
nOutFlds = n_out_flds;
tuple1 = new Tuple();
try {
tuple1.setHdr(in1_len, _in1, s1_sizes);
} catch (Exception e) {
throw new FileScanException(e, "setHdr() failed");
}
t1_size = tuple1.size();
try {
f = new Heapfile(file_name);
} catch (Exception e) {
throw new FileScanException(e, "Create new heapfile failed");
}
try {
scan = f.openScan();
} catch (Exception e) {
throw new FileScanException(e, "openScan() failed");
}
}
/**
* @return the result tuple
* @exception JoinsException some join exception
* @exception IOException I/O errors
* @exception InvalidTupleSizeException invalid tuple size
* @exception InvalidTypeException tuple type not valid
* @exception PageNotReadException exception from lower layer
* @exception PredEvalException exception from PredEval class
* @exception UnknowAttrType attribute type unknown
* @exception FieldNumberOutOfBoundException array out of bounds
* @exception WrongPermat exception for wrong FldSpec argument
*/
public Tuple get_next()
throws JoinsException, IOException, InvalidTupleSizeException, InvalidTypeException,
PageNotReadException, PredEvalException, UnknowAttrType, FieldNumberOutOfBoundException,
WrongPermat {
RID rid = new RID();
;
while (true) {
if ((tuple1 = scan.getNext(rid)) == null) {
return null;
}
tuple1.setHdr(in1_len, _in1, s_sizes);
if (PredEval.Eval(OutputFilter, tuple1, null, _in1, null) == true) {
Projection.Project(tuple1, _in1, Jtuple, perm_mat, nOutFlds);
return Jtuple;
}
}
}