be.SIRAPRISE.typeimplementations

Class PROJECT

java.lang.Object

be.SIRAPRISE.typeimplementations.RelationalOperator

be.SIRAPRISE.typeimplementations.PROJECT

All Implemented Interfaces:

OperatorGenerator

@OperatorGeneratorCharacteristics(maximumArgumentCount=2,
                                  minimumArgumentCount=2,
                                  name="PROJECT",
                                  signature={EXPRESSION,STRING})
 @MonoRelationOperator
public abstract class PROJECT
extends RelationalOperator

Author:

erwin

Constructor Summary

Constructors

Constructor and Description
PROJECT()

Method Summary

Modifier and Type	Method and Description
static Relation	computeProjection(Relation relation, NameIdentifier... attributes)
OperatorImplementation_V0105	getOperatorImplementation(OperatorGeneratorArgument[] args) Gets an implementation instance of the operator.

Methods inherited from class be.SIRAPRISE.typeimplementations.RelationalOperator

getInvocationName, getMaximumArgumentCount, getMinimumArgumentCount, getName, getOperatorGeneratorSignature, isMonoRelationOperator, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

PROJECT

public PROJECT()

Method Detail

computeProjection

public static Relation computeProjection(Relation relation,
                                         NameIdentifier... attributes)
                                  throws EvaluationException

Parameters:

relation - the relation subjected to a projection

attributes - the attributes to be retained in the result

Returns:

The result of projecting the given relation over the specified projection attributes

Throws:

EvaluationException - If the evaluation failed for any reason. See the contained getCause() exception for more detail

getOperatorImplementation

public final OperatorImplementation_V0105 getOperatorImplementation(OperatorGeneratorArgument[] args)

Description copied from interface: OperatorGenerator

Gets an implementation instance of the operator.

Parameters:

args - The arguments from which the instance is to be created. There must be exactly as many arguments as there are elements in the list returned from OperatorGenerator.getOperatorGeneratorSignature(). The correspondence between OperatorGeneratorArgumentType values and OperatorGeneratorArgument types is given in the table below :

correspondence between OperatorGeneratorArgumentType values and OperatorGeneratorArgument types

OperatorGeneratorArgumentType value	OperatorGeneratorArgument type
EXPRESSION	NonScalarOperatorGeneratorExpressionArgument
EXPRESSIONWITHSCOPE	NonScalarOperatorGeneratorExpressionArgument
STRING	NonScalarOperatorGeneratorTextArgument

Returns:

an instance of the operator