Class Select

Represents the Selection step of Query Evaluation.

Inheritance

object

Select

Implements

IUnaryOperator

ISparqlAlgebra

IVisitable

IProcessable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: VDS.RDF.Query.Algebra

Assembly: dotNetRdf.dll

Syntax

public class Select : IUnaryOperator, ISparqlAlgebra, IVisitable, IProcessable

Remarks

Selection trims variables from the Multiset that are not needed in the final output.

Constructors

Select(ISparqlAlgebra, bool, IEnumerable<SparqlVariable>)

Creates a new Select.

Declaration

public Select(ISparqlAlgebra pattern, bool selectAll, IEnumerable<SparqlVariable> variables)

Parameters

Type	Name	Description
ISparqlAlgebra	pattern	Inner Pattern.
bool	selectAll	Whether we are selecting all variables.
IEnumerable<SparqlVariable>	variables	Variables to Select.

Properties

FixedVariables

Gets the enumeration of fixed variables in the algebra i.e. variables that are guaranteed to have a bound value.

Declaration

public IEnumerable<string> FixedVariables { get; }

Property Value

Type	Description
IEnumerable<string>

FloatingVariables

Gets the enumeration of floating variables in the algebra i.e. variables that are not guaranteed to have a bound value.

Declaration

public IEnumerable<string> FloatingVariables { get; }

Property Value

Type	Description
IEnumerable<string>

InnerAlgebra

Gets the Inner Algebra.

Declaration

public ISparqlAlgebra InnerAlgebra { get; }

Property Value

Type	Description
ISparqlAlgebra

IsSelectAll

Does this operator select all variables?.

Declaration

public bool IsSelectAll { get; }

Property Value

Type	Description
bool

SparqlVariables

Gets the SPARQL Variables used.

Declaration

public IEnumerable<SparqlVariable> SparqlVariables { get; }

Property Value

Type	Description
IEnumerable<SparqlVariable>

Remarks

If the Query supplied in the SparqlEvaluationContext is non-null then it's Variables are used rather than these.

Variables

Gets the Variables used in the Algebra.

Declaration

public IEnumerable<string> Variables { get; }

Property Value

Type	Description
IEnumerable<string>

Methods

Accept<T>(ISparqlAlgebraVisitor<T>)

Accept a simple algebra visitor.

Declaration

public T Accept<T>(ISparqlAlgebraVisitor<T> visitor)

Parameters

Type	Name	Description
ISparqlAlgebraVisitor<T>	visitor	The visitor implementation.

Returns

Type	Description
T

Type Parameters

Name	Description
T	The type returned by the Visit methods of the visitor.

Accept<TResult, TContext>(ISparqlQueryAlgebraProcessor<TResult, TContext>, TContext)

Called by an algebra visitor to process an item by invoking the appropriate method on the processor passed in.

Declaration

public TResult Accept<TResult, TContext>(ISparqlQueryAlgebraProcessor<TResult, TContext> processor, TContext context)

Parameters

Type	Name	Description
ISparqlQueryAlgebraProcessor<TResult, TContext>	processor	The processor to invoke.
TContext	context	The context to pass to the processor.

Returns

Type	Description
TResult	The result of invoking the processor method.

Type Parameters

Name	Description
TResult	The type of result returned by the processor.
TContext	The type of the context object to be provided to the processor.

ToGraphPattern()

Throws an error as a Select() cannot be converted back to a Graph Pattern.

Declaration

public GraphPattern ToGraphPattern()

Returns

Type	Description
GraphPattern

Exceptions

Type	Condition
NotSupportedException	Thrown since a Select() cannot be converted back to a Graph Pattern.

ToQuery()

Converts the Algebra back to a SPARQL Query.

Declaration

public SparqlQuery ToQuery()

Returns

Type	Description
SparqlQuery

ToString()

Gets the String representation of the Algebra.

Declaration

public override string ToString()

Returns

Type	Description
string

Overrides

object.ToString()

Transform(IAlgebraOptimiser)

Transforms the Inner Algebra using the given Optimiser.

Declaration

public ISparqlAlgebra Transform(IAlgebraOptimiser optimiser)

Parameters

Type	Name	Description
IAlgebraOptimiser	optimiser	Optimiser.

Returns

Type	Description
ISparqlAlgebra

Implements

IUnaryOperator

ISparqlAlgebra

IVisitable

IProcessable

Extension Methods

Extensions.ToSafeString(object)

Extensions.AsEnumerable<T>(T)