org.apache.pig.newplan.logical.expression
Class ConstantExpression

java.lang.Object
  org.apache.pig.newplan.Operator
      org.apache.pig.newplan.logical.expression.LogicalExpression
          org.apache.pig.newplan.logical.expression.ColumnExpression
              org.apache.pig.newplan.logical.expression.ConstantExpression

public class ConstantExpression
extends ColumnExpression

A constant

Field Summary

Fields inherited from class org.apache.pig.newplan.logical.expression.LogicalExpression

fieldSchema, uidOnlyFieldSchema

Fields inherited from class org.apache.pig.newplan.Operator

annotations, hashPrime, location, name, plan

Constructor Summary

ConstantExpression(OperatorPlan plan, Object val)
Adds expression to the plan

Method Summary

void	accept(PlanVisitor v) Accept a visitor at this node in the graph.
LogicalExpression	deepCopy(LogicalExpressionPlan lgExpPlan) Create the deep copy of this expression and add that into the passed LogicalExpressionPlan Return the copy of this expression with updated logical expression plan.
LogicalSchema.LogicalFieldSchema	getFieldSchema() Get the field schema for the output of this expression operator.
Object	getValue() Get the value of this constant.
boolean	isEqual(Operator other) This is like a shallow equals comparison.
void	setValue(Object val)

Methods inherited from class org.apache.pig.newplan.logical.expression.LogicalExpression

getNextUid, getType, hasFieldSchema, neverUseForRealSetFieldSchema, resetFieldSchema, resetNextUid, resetUid, toString

Methods inherited from class org.apache.pig.newplan.Operator

annotate, getAnnotation, getLocation, getName, getPlan, removeAnnotation, setLocation, setPlan

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantExpression

public ConstantExpression(OperatorPlan plan,
                          Object val)

Adds expression to the plan

Parameters:

plan - LogicalExpressionPlan this constant is a part of.

val - Value of this constant.

Method Detail

accept

public void accept(PlanVisitor v)
            throws FrontendException

Description copied from class: Operator

Accept a visitor at this node in the graph.

Specified by:

accept in class Operator

Parameters:

v - Visitor to accept.

Throws:

FrontendException

getValue

public Object getValue()

Get the value of this constant.

Returns:

value of the constant

setValue

public void setValue(Object val)

isEqual

public boolean isEqual(Operator other)
                throws FrontendException

Description copied from class: Operator

This is like a shallow equals comparison. It returns true if two operators have equivalent properties even if they are different objects. Here properties mean equivalent plan and equivalent name.

Specified by:

isEqual in class Operator

Returns:

true if two object have equivalent properties, else false

Throws:

FrontendException

getFieldSchema

public LogicalSchema.LogicalFieldSchema getFieldSchema()
                                                throws FrontendException

Description copied from class: LogicalExpression

Get the field schema for the output of this expression operator. This does not merely return the field schema variable. If schema is not yet set, this will attempt to construct it. Therefore it is abstract since each operator will need to construct its field schema differently.

Specified by:

getFieldSchema in class LogicalExpression

Returns:

the FieldSchema

Throws:

FrontendException

deepCopy

public LogicalExpression deepCopy(LogicalExpressionPlan lgExpPlan)
                           throws FrontendException

Description copied from class: LogicalExpression

Create the deep copy of this expression and add that into the passed LogicalExpressionPlan Return the copy of this expression with updated logical expression plan.

Specified by:

deepCopy in class LogicalExpression

Parameters:

lgExpPlan - LogicalExpressionPlan in which this expression will be added.

Returns:

LogicalExpression with its own logical expression plan.

Throws:

FrontendException