com.hp.hpl.jena.graph.query
Class Expression.Base

java.lang.Object
  com.hp.hpl.jena.graph.query.Expression.Base

All Implemented Interfaces:

Expression

Direct Known Subclasses:

Expression.Application, Expression.BoolConstant, Expression.Literal, Expression.Variable

Enclosing class:

Expression

public abstract static class Expression.Base

extends java.lang.Object

implements Expression

An abstract base class for Expressions; over-ride as appropriate. The sub-classes may be more useful. Base provides an implementation of prepare which produces a slow Valuator that relies on the Base's evalBool.

Nested Class Summary

Nested classes inherited from class com.hp.hpl.jena.graph.query.Expression

Expression.Application, Expression.Base, Expression.BoolConstant, Expression.Literal, Expression.Util, Expression.Valof, Expression.Variable

Field Summary

Fields inherited from interface com.hp.hpl.jena.graph.query.Expression

FALSE, TRUE

Constructor Summary

Expression.Base()

Method Summary

int	argCount() If this Expression is an application, answer the number of arguments that it has.
Expression	getArg(int i) If this Expression is an application, and 0 <= i < argCount(), answer the ith argument.
java.lang.String	getFun() If this Expression is an application, return the string identifying the function, which should be a URI.
java.lang.String	getName() If this Expression is a variable, answer a [non-null] String which is its name.
java.lang.Object	getValue() If this Expression is a literal, answer the value of that literal.
boolean	isApply() Answer true iff this Expression represents the application of some function [or operator] to some arguments [or operands].
boolean	isLiteral() Answer true iff this Expression represents a literal [Java object] value.
boolean	isVariable() Answer true iff this Expression represents a variable.
Valuator	prepare(VariableIndexes vi) Answer a Valuator which does the same evaluation as this Expression when supplied with a mapping from variable indexes to their values.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.hp.hpl.jena.graph.query.Expression

evalBool

Constructor Detail

Expression.Base

public Expression.Base()

Method Detail

isVariable

public boolean isVariable()

Description copied from interface: Expression

Answer true iff this Expression represents a variable.

Specified by:

isVariable in interface Expression

isApply

public boolean isApply()

Description copied from interface: Expression

Answer true iff this Expression represents the application of some function [or operator] to some arguments [or operands].

Specified by:

isApply in interface Expression

isLiteral

public boolean isLiteral()

Description copied from interface: Expression

Answer true iff this Expression represents a literal [Java object] value.

Specified by:

isLiteral in interface Expression

getName

public java.lang.String getName()

Description copied from interface: Expression

If this Expression is a variable, answer a [non-null] String which is its name. Otherwise the behaviour is unspecified.

Specified by:

getName in interface Expression

getValue

public java.lang.Object getValue()

Description copied from interface: Expression

If this Expression is a literal, answer the value of that literal. Otherwise the behaviour is unspecified.

Specified by:

getValue in interface Expression

argCount

public int argCount()

Description copied from interface: Expression

If this Expression is an application, answer the number of arguments that it has. Otherwise the behaviour is unspecified.

Specified by:

argCount in interface Expression

getFun

public java.lang.String getFun()

Description copied from interface: Expression

If this Expression is an application, return the string identifying the function, which should be a URI. Otherwise the behaviour is unspecified.

Specified by:

getFun in interface Expression

getArg

public Expression getArg(int i)

Description copied from interface: Expression

If this Expression is an application, and 0 <= i < argCount(), answer the ith argument. Otherwise the behaviour is unspecified.

Specified by:

getArg in interface Expression

prepare

public Valuator prepare(VariableIndexes vi)

Description copied from interface: Expression

Answer a Valuator which does the same evaluation as this Expression when supplied with a mapping from variable indexes to their values. The composition of the variable->index map vi and the index->value map given to the valuator is equivalent to the VariableValues map that would be supplied to evalBool.

Specified by:

prepare in interface Expression