org.eigenbase.rex
Class RexInputRef

java.lang.Object
  org.eigenbase.rex.RexNode
      org.eigenbase.rex.RexVariable
          org.eigenbase.rex.RexSlot
              org.eigenbase.rex.RexInputRef

public class RexInputRef
extends RexSlot

Variable which references a field of an input relational expression.

Fields of the input are 0-based. If there is more than one input, they are numbered consecutively. For example, if the inputs to a join are

• Input #0: EMP(EMPNO, ENAME, DEPTNO) and
• Input #1: DEPT(DEPTNO AS DEPTNO2, DNAME)

then the fields are:

• Field #0: EMPNO
• Field #1: ENAME
• Field #2: DEPTNO (from EMP)
• Field #3: DEPTNO2 (from DEPT)
• Field #4: DNAME

So RexInputRef(3,Integer) is the correct reference for the field DEPTNO2.

Since:

Nov 24, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rex/RexInputRef.java#16 $

Author:

jhyde

Field Summary

private static String[]

names

Fields inherited from class org.eigenbase.rex.RexSlot

index

Fields inherited from class org.eigenbase.rex.RexVariable

name, type

Fields inherited from class org.eigenbase.rex.RexNode

digest, EMPTY_ARRAY

Constructor Summary

RexInputRef(int index, RelDataType type)
Creates an input variable.

Method Summary

<R> R	accept(RexVisitor<R> visitor) Accepts a visitor, dispatching to the right overloaded visitXxx method.
RexInputRef	clone()
static String	createName(int index) Creates a name for an input reference, of the form "$index".

Methods inherited from class org.eigenbase.rex.RexSlot

getIndex, makeArray

Methods inherited from class org.eigenbase.rex.RexVariable

getName, 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

names

private static final String[] names

Constructor Detail

RexInputRef

public RexInputRef(int index,
                   RelDataType type)

Creates an input variable.

Parameters:

index - Index of the field in the underlying rowtype

type - Type of the column

"Precondition:"

type != null, index >= 0

Method Detail

clone

public RexInputRef 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

createName

public static String createName(int index)

Creates a name for an input reference, of the form "$index". If the index is low, uses a cache of common names, to reduce gc.