de.fuberlin.wiwiss.d2rq.expr

Class Constant

java.lang.Object

de.fuberlin.wiwiss.d2rq.expr.Expression

de.fuberlin.wiwiss.d2rq.expr.Constant

Direct Known Subclasses:

ConstantEx

public class Constant
extends Expression

A constant-valued expression. This class currently doesn't track its type (Is the constant a number or string, for example?). Since we need to know the type when writing the constant to SQL, we keep a reference to an attribute around. The constant is assumed to have the same type as that attribute. This is an ugly hack. TODO Should have a DataType instead of the silly column reference

Author:

Richard Cyganiak (richard@cyganiak.de)

Field Summary

Fields inherited from class de.fuberlin.wiwiss.d2rq.expr.Expression

FALSE, TRUE

Constructor Summary

Constructors

Constructor and Description
Constant(String value)
Constant(String value, Attribute attributeForTrackingType)

Method Summary

Methods

Modifier and Type	Method and Description
Set<Attribute>	attributes()
boolean	equals(Object other)
int	hashCode()
boolean	isFalse()
boolean	isTrue()
Expression	renameAttributes(ColumnRenamer columnRenamer)
String	toSQL(ConnectedDB database, AliasMap aliases)
String	toString()
String	value()

Methods inherited from class de.fuberlin.wiwiss.d2rq.expr.Expression

and, or

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Constant

public Constant(String value)

Constant

public Constant(String value,
        Attribute attributeForTrackingType)

Method Detail

value

public String value()

attributes

public Set<Attribute> attributes()

Specified by:

attributes in class Expression

isFalse

public boolean isFalse()

Specified by:

isFalse in class Expression

isTrue

public boolean isTrue()

Specified by:

isTrue in class Expression

renameAttributes

public Expression renameAttributes(ColumnRenamer columnRenamer)

Specified by:

renameAttributes in class Expression

toSQL

public String toSQL(ConnectedDB database,
           AliasMap aliases)

Specified by:

toSQL in class Expression

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object