org.openanzo.glitter.query
Class Projection

java.lang.Object
  org.openanzo.glitter.query.Projection

All Implemented Interfaces:

QueryResultForm

public class Projection
extends java.lang.Object
implements QueryResultForm

Projection handles the SELECT SPARQL query form, in which the result set is returned after being projected out to only the selected variables.

Author:

lee

Constructor Summary

Projection()
Default constructor.

Projection(boolean distinct)
Selects for all variables.

Projection(Variable[] variables, Variable[] groupByVars, boolean distinct, boolean reduced, boolean projectCount, boolean countDistinct)

Method Summary

Variable[]	getProjectedVariables()
boolean	isDistinct()
boolean	isReduced()
boolean	projectCount()
SolutionSet	refineSolutions(SolutionSet results) Result forms are given a chance to apply solution modifiers to the solution set before transforming the results.
java.lang.Object	serializeResults(SolutionSet results)
SolutionSet	serializeResultsAsResultSet(SolutionSet solutions) Serializing a Projection is a no-op.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Projection

public Projection(Variable[] variables,
                  Variable[] groupByVars,
                  boolean distinct,
                  boolean reduced,
                  boolean projectCount,
                  boolean countDistinct)

Parameters:

variables - The variables being selected for

distinct - If true, return only distinct resultset rows

reduced - If true (and distinct is false), indicates that the implementation is free to return anywhere between 1 and the standard (algebra-defined) cardinality of each solution.

projectCount - If true, calculate aggregate function COUNT on all grouped solutions.

countDistinct - If true, only sum up distinct solutions when calculating count.

Projection

public Projection()

Default constructor. Selects for all variables and all duplicate rows.

Projection

public Projection(boolean distinct)

Selects for all variables.

Parameters:

distinct - If true, return only distinct resultset rows

Method Detail

isDistinct

public boolean isDistinct()

Returns:

Whether this projection eliminates duplicate result rows

isReduced

public boolean isReduced()

Returns:

Whether this is a REDUCED query. See #Projection(Variable[], boolean, boolean).

projectCount

public boolean projectCount()

getProjectedVariables

public Variable[] getProjectedVariables()

Returns:

The array of selected variables.

serializeResults

public java.lang.Object serializeResults(SolutionSet results)

Specified by:

serializeResults in interface QueryResultForm

Parameters:

results - The solution set after all solution modified have been applied.

Returns:

A form of the solution set specific to this QueryResultForm.

serializeResultsAsResultSet

public SolutionSet serializeResultsAsResultSet(SolutionSet solutions)

Serializing a Projection is a no-op.

Parameters:

solutions - The refined SolutionSet

Returns:

The refined SolutionSet

refineSolutions

public SolutionSet refineSolutions(SolutionSet results)

Description copied from interface: QueryResultForm

Result forms are given a chance to apply solution modifiers to the solution set before transforming the results. (For example, Projection might apply DISTINCT here.

Specified by:

refineSolutions in interface QueryResultForm

Parameters:

results - The original solution set

Returns:

The (possibly) modified solution set

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object