be.SIRAPRISE.ra

Class PROJECT

java.lang.Object

be.SIRAPRISE.ra.RelationalOperator

be.SIRAPRISE.ra.PROJECT

public abstract class PROJECT
extends RelationalOperator

Author:

erwin

Constructor Summary

Constructors

Constructor and Description
PROJECT()

Method Summary

Modifier and Type	Method and Description
static RelationBuffer	computeProjection(RelationBuffer relationBuffer, NameIdentifier... attributes)
static Relation	computeProjection(Relation relation, NameIdentifier... attributes)
int	getMaximumArgumentCount() Gets the maximum argument count for this operator.
int	getMinimumArgumentCount() Gets the minimum argument count for this operator.
java.lang.String	getName() Gets the operator name
boolean	isMonoRelationOperator() Checks if the operator takes only one Relation as input
static PROJECTInvocationResultDetails	validateExpressionDetails(Heading inputHeading, java.util.Set<NameIdentifier> attributeNames, java.lang.String inputPredicate, java.util.Collection<? extends KeyDef> inputKeySpecifications)

Methods inherited from class be.SIRAPRISE.ra.RelationalOperator

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

computeProjection

public static RelationBuffer computeProjection(RelationBuffer relationBuffer,
                                               NameIdentifier... attributes)

Parameters:

relationBuffer - the buffer holding a 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

validateExpressionDetails

public static PROJECTInvocationResultDetails validateExpressionDetails(Heading inputHeading,
                                                                       java.util.Set<NameIdentifier> attributeNames,
                                                                       java.lang.String inputPredicate,
                                                                       java.util.Collection<? extends KeyDef> inputKeySpecifications)
                                                                throws NonExistingAttributeException

Parameters:

attributeNames - The set of projection attributes

inputHeading - The heading of a relational expression that is subjected to projection

inputPredicate - The predicate of which the relation subjected to the projection is the extension

inputKeySpecifications - The keys known to be satisfied by the relation that is subjected to this projection

Returns:

The technical details of the projection invocation

Throws:

NonExistingAttributeException - If an attribute is mentioned in the projection attribute list that does not appear in the heading

getMaximumArgumentCount

public final int getMaximumArgumentCount()

Description copied from class: RelationalOperator

Gets the maximum argument count for this operator. Note that stuff like rename lists are regarded as an argument as far as this count is concerned

Specified by:

getMaximumArgumentCount in class RelationalOperator

Returns:

the maximum argument count for this operator.

getMinimumArgumentCount

public final int getMinimumArgumentCount()

Description copied from class: RelationalOperator

Gets the minimum argument count for this operator. Note that stuff like rename lists are regarded as an argument as far as this count is concerned

Specified by:

getMinimumArgumentCount in class RelationalOperator

Returns:

the minimum argument count for this operator

getName

public final java.lang.String getName()

Description copied from class: RelationalOperator

Gets the operator name

Specified by:

getName in class RelationalOperator

Returns:

the operator name

isMonoRelationOperator

public final boolean isMonoRelationOperator()

Description copied from class: RelationalOperator

Checks if the operator takes only one Relation as input

Specified by:

isMonoRelationOperator in class RelationalOperator

Returns:

true if the operator takes only one Relation as input