org.eigenbase.rex
Class RexNode

java.lang.Object
  org.eigenbase.rex.RexNode

Direct Known Subclasses:

JavaRowExpression, RexCall, RexFieldAccess, RexLiteral, RexRangeRef, RexVariable

public abstract class RexNode
extends Object

Row expression.

Every row-expression has a type. (Compare with SqlNode, which is created before validation, and therefore types may not be available.)

Some common row-expressions are: RexLiteral (constant value), RexVariable (variable), RexCall (call to operator with operands). Expressions are generally created using a RexBuilder factory.

Since:

Nov 22, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rex/RexNode.java#14 $

Author:

jhyde

Field Summary

protected String	digest
static RexNode[]	EMPTY_ARRAY

Constructor Summary

RexNode()

Method Summary

abstract <R> R	accept(RexVisitor<R> visitor) Accepts a visitor, dispatching to the right overloaded visitXxx method.
abstract RexNode	clone()
RexKind	getKind() Returns the kind of node this is.
abstract RelDataType	getType()
boolean	isA(RexKind kind)
boolean	isAlwaysTrue() Returns whether this expression always returns true.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_ARRAY

public static final RexNode[] EMPTY_ARRAY

digest

protected String digest

Constructor Detail

RexNode

public RexNode()

Method Detail

getType

public abstract RelDataType getType()

clone

public abstract RexNode clone()

Overrides:

clone in class Object

isAlwaysTrue

public boolean isAlwaysTrue()

Returns whether this expression always returns true. (Such as if this expression is equal to the literal TRUE.)

isA

public boolean isA(RexKind kind)

getKind

public RexKind getKind()

Returns the kind of node this is.

Returns:

A RexKind value, never null

"Postcondition:"

return != null

toString

public String toString()

Overrides:

toString in class Object

accept

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

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.