net.sf.saffron.rex
Class RexRangeRef

java.lang.Object
  |
  +--net.sf.saffron.rex.RexNode
        |
        +--net.sf.saffron.rex.RexRangeRef

public class RexRangeRef

extends RexNode

Reference to a range of columns.

This construct is used only during the process of translating a SQL tree to a rel/rex tree. Regular rex trees do not contain this construct.

While translating a join of EMP(EMPNO, ENAME, DEPTNO) to DEPT(DEPTNO2, DNAME) we create RexRangeRef(DeptType,3) to represent the pair of columns (DEPTNO2, DNAME) which came from DEPT. The type has 2 columns, and therefore the range represents columns {3, 4} of the input.

Suppose we later create a reference to the DNAME field of this RexRangeRef; it will return a RexInputRef(5,Integer), and the RexRangeRef will disappear.

Since:

Nov 23, 2003

Version:

$Id: $

Author:

jhyde

Field Summary

int	offset
private SaffronType	type

Fields inherited from class net.sf.saffron.rex.RexNode

digest

Constructor Summary

(package private)

RexRangeRef(SaffronType rangeType, int offset) Creates a range reference.

Method Summary

Object	clone()
SaffronType	getType()

Methods inherited from class net.sf.saffron.rex.RexNode

getKind, isA, isAlwaysTrue, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

type

private final SaffronType type

offset

public final int offset

Constructor Detail

RexRangeRef

RexRangeRef(SaffronType rangeType,
            int offset)

Creates a range reference.

Parameters:

rangeType - Type of the record returned

offset - Offset of the first column within the input record

Method Detail

getType

public SaffronType getType()

Specified by:

getType in class RexNode

clone

public Object clone()

Specified by:

clone in class RexNode