org.eigenbase.rex
Class RexRangeRef

java.lang.Object
  org.eigenbase.rex.RexNode
      org.eigenbase.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: //open/dev/farrago/src/org/eigenbase/rex/RexRangeRef.java#15 $

Author:

jhyde

Field Summary

private int	offset
private RelDataType	type

Fields inherited from class org.eigenbase.rex.RexNode

digest, EMPTY_ARRAY

Constructor Summary

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

Method Summary

<R> R	accept(RexVisitor<R> visitor) Accepts a visitor, dispatching to the right overloaded visitXxx method.
RexRangeRef	clone()
int	getOffset()
RelDataType	getType()

Methods inherited from class org.eigenbase.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 RelDataType type

offset

private final int offset

Constructor Detail

RexRangeRef

RexRangeRef(RelDataType 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 RelDataType getType()

Specified by:

getType in class RexNode

getOffset

public int getOffset()

clone

public RexRangeRef clone()

Specified by:

clone in class RexNode

accept

public <R> R accept(RexVisitor<R> visitor)

Description copied from class: RexNode

Accepts a visitor, dispatching to the right overloaded visitXxx method.

Also see RexProgram.apply(RexVisitor, RexNode[], RexNode), which applies a visitor to several expressions simultaneously.

Specified by:

accept in class RexNode