org.apache.pig.newplan.logical.expression

Class LogicalExpression

java.lang.Object

org.apache.pig.newplan.Operator

org.apache.pig.newplan.logical.expression.LogicalExpression

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

BinaryExpression, BinCondExpression, ColumnExpression, UnaryExpression, UserFuncExpression

public abstract class LogicalExpression
extends Operator

Logical representation of expression operators. Expression operators have a data type and a uid. Uid is a unique id for each expression.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected LogicalSchema.LogicalFieldSchema	fieldSchema
protected LogicalSchema.LogicalFieldSchema	uidOnlyFieldSchema

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

annotations, hashPrime, location, name, plan

Constructor Summary

Constructors

Constructor and Description
LogicalExpression(java.lang.String name, OperatorPlan plan)

Method Summary

Modifier and Type	Method and Description
abstract 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.
abstract LogicalSchema.LogicalFieldSchema	getFieldSchema() Get the field schema for the output of this expression operator.
static long	getNextUid()
byte	getType() Get the data type for this expression.
boolean	hasFieldSchema() This is a convenience method to avoid the side-effectful nature of getFieldSchema().
void	neverUseForRealSetFieldSchema(LogicalSchema.LogicalFieldSchema fs)
void	resetFieldSchema()
static void	resetNextUid()
void	resetUid() Erase all cached uid, regenerate uid when we regenerating schema.
java.lang.String	toString()

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

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

Methods inherited from class java.lang.Object

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

Field Detail

fieldSchema

protected LogicalSchema.LogicalFieldSchema fieldSchema

uidOnlyFieldSchema

protected LogicalSchema.LogicalFieldSchema uidOnlyFieldSchema

Constructor Detail

LogicalExpression

public LogicalExpression(java.lang.String name,
                         OperatorPlan plan)

Parameters:

name - of the operator

plan - LogicalExpressionPlan this is part of

Method Detail

getNextUid

public static long getNextUid()

resetNextUid

public static void resetNextUid()

hasFieldSchema

public boolean hasFieldSchema()

This is a convenience method to avoid the side-effectful nature of getFieldSchema(). It simply returns whether or not fieldSchema is currently null.

getFieldSchema

public abstract LogicalSchema.LogicalFieldSchema getFieldSchema()
                                                         throws FrontendException

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.

Returns:

the FieldSchema

Throws:

FrontendException

resetFieldSchema

public void resetFieldSchema()

getType

public byte getType()
             throws FrontendException

Get the data type for this expression.

Returns:

data type, one of the static bytes of DataType

Throws:

FrontendException

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

neverUseForRealSetFieldSchema

public void neverUseForRealSetFieldSchema(LogicalSchema.LogicalFieldSchema fs)
                                   throws FrontendException

Throws:

FrontendException

deepCopy

public abstract LogicalExpression deepCopy(LogicalExpressionPlan lgExpPlan)
                                    throws FrontendException

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.

Parameters:

lgExpPlan - LogicalExpressionPlan in which this expression will be added.

Returns:

LogicalExpression with its own logical expression plan.

Throws:

IOException.

FrontendException

resetUid

public void resetUid()

Erase all cached uid, regenerate uid when we regenerating schema. This process currently only used in ImplicitSplitInsert, which will insert split and invalidate some uids in plan