public class ConstantValueMaker extends Object implements ValueMaker
FixedNodeMaker
doesn't use an instance
of this class, but handles the constantness of its
underlying values directly.
This class is only used where we need to produce constant
strings, rather than constant RDF nodes.NULL
Constructor and Description |
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ConstantValueMaker(String constant) |
Modifier and Type | Method and Description |
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void |
describeSelf(NodeSetFilter c) |
String |
makeValue(ResultRow row)
Retrieves a value from a database row according to some rule or pattern.
|
List<OrderSpec> |
orderSpecs(boolean ascending) |
Set<ProjectionSpec> |
projectionSpecs()
Returns a set of all
ProjectionSpec s containing data necessary
for this ValueSource. |
ValueMaker |
renameAttributes(ColumnRenamer renamer) |
Expression |
valueExpression(String value)
A SQL expression that selects only rows where this value maker
produces the specified value.
|
public ConstantValueMaker(String constant)
public Expression valueExpression(String value)
ValueMaker
Expression.FALSE
if this
value maker is incapable of producing the value.valueExpression
in interface ValueMaker
value
- A valuepublic Set<ProjectionSpec> projectionSpecs()
ValueMaker
ProjectionSpec
s containing data necessary
for this ValueSource.projectionSpecs
in interface ValueMaker
ProjectionSpec
spublic String makeValue(ResultRow row)
ValueMaker
makeValue
in interface ValueMaker
row
- the database rowpublic void describeSelf(NodeSetFilter c)
describeSelf
in interface ValueMaker
public ValueMaker renameAttributes(ColumnRenamer renamer)
renameAttributes
in interface ValueMaker
public List<OrderSpec> orderSpecs(boolean ascending)
orderSpecs
in interface ValueMaker