iterator
Class FileScan

java.lang.Object
  iterator.Iterator
      iterator.FileScan

All Implemented Interfaces:

Flags

public class FileScan

extends Iterator

open a heapfile and according to the condition expression to get output file, call get_next to get all tuples

Field Summary

FldSpec[]

perm_mat

Fields inherited from class iterator.Iterator

closeFlag

Fields inherited from interface global.Flags

DEBUG, TEST

Constructor Summary

FileScan(java.lang.String file_name, AttrType[] in1, short[] s1_sizes, short len_in1, int n_out_flds, FldSpec[] proj_list, CondExpr[] outFilter)
constructor

Method Summary

void	close() implement the abstract method close() from super class Iterator to finish cleaning up
Tuple	get_next() abstract method, every subclass must implement it.
FldSpec[]	show()

Methods inherited from class iterator.Iterator

free_buffer_pages, get_buffer_pages

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

perm_mat

public FldSpec[] perm_mat

Constructor Detail

FileScan

public FileScan(java.lang.String file_name,
                AttrType[] in1,
                short[] s1_sizes,
                short len_in1,
                int n_out_flds,
                FldSpec[] proj_list,
                CondExpr[] outFilter)
         throws java.io.IOException,
                FileScanException,
                TupleUtilsException,
                InvalidRelation

constructor

Parameters:

file_name - heapfile to be opened

len_in1 - number of attributes in the input tuple

n_out_flds - number of fields in the out tuple

proj_list - shows what input fields go where in the output tuple

outFilter - select expressions

Throws:

java.io.IOException - some I/O fault

FileScanException - exception from this class

TupleUtilsException - exception from this class

InvalidRelation - invalid relation

Method Detail

show

public FldSpec[] show()

Returns:

shows what input fields go where in the output tuple

get_next

public Tuple get_next()
               throws JoinsException,
                      java.io.IOException,
                      InvalidTupleSizeException,
                      InvalidTypeException,
                      PageNotReadException,
                      PredEvalException,
                      UnknowAttrType,
                      FieldNumberOutOfBoundException,
                      WrongPermat

Description copied from class: Iterator

abstract method, every subclass must implement it.

Specified by:

get_next in class Iterator

Returns:

the result tuple

Throws:

JoinsException - some join exception

java.io.IOException - I/O errors

InvalidTupleSizeException - invalid tuple size

InvalidTypeException - tuple type not valid

PageNotReadException - exception from lower layer

PredEvalException - exception from PredEval class

UnknowAttrType - attribute type unknown

FieldNumberOutOfBoundException - array out of bounds

WrongPermat - exception for wrong FldSpec argument

close

public void close()

implement the abstract method close() from super class Iterator to finish cleaning up

Specified by:

close in class Iterator